Infinities and singularities are equivalent when mass is absent and entropy (that is, randomness) is maximum, because in both states the ability of the universe to scale itself is lost.
It is called conformal equivalence. It means that the shape of everything in two systems is the same; the scale is indeterminate or irrelevant. Size can’t be measured.
Warning to the faint of heart: this essay will reveal ideas that might change the way some readers think about the universe. Keep an open mind.
What is the fate of the cosmos? Almost everyone agrees that it will expand exponentially, possibly forever. As it does, all matter will be sucked into black holes like water into bathtub drains where — perhaps over trillions of years — it will evaporate by a mechanism believed to produce Hawking radiation; mass converts into massless photons and radiates outward until every black hole evaporates and disappears.
Sir Roger Penrose, the brilliant mathematical physicist, has said that new satellite data might support his theory of Eons, which asserts among other things that the universe expands while black holes collect and evaporate away all matter; entropy (or randomness) increases to maximum.
At the termination of the Eon the universe cannot tell whether it is at its beginning or its end because it doesn’t know what size it is; all its metrics become equivalent to those found in the singularity that many speculate preceded the emergence of the Universe humans find themselves in today.
In the unimaginable heat of a singularity, the concept of mass also disappears; it becomes irrelevant. Energy dwarfs mass to overwhelm it; runaway entropy (randomness) goes to maximum.
With no mass the concept of scale disappears. Without mass all the gravitational degrees of freedom vanish. The universe doesn’t know what size it is or if it is any size at all.
Entropy (or randomness) of “the singularity” initiates the Big Bang in the same way as a maximally expanded and evaporated universe; the two states — infinity and singularity — are equivalent. They are not distinguishable; one is like the other and emerges from the other.
Both the singularity and the infinitely expanded universe are unable to determine how big they are because both lose the ability to scale themselves when matter is no longer present; both states have maximum entropy; the distribution of energy becomes infinitely random.
The result is that the expansion of a maximally expanded universe starts anew as if it were a singularity. A new “eon” begins at the end of each expansion; the universe expands in stages with the beginning of each stage indistinguishable from a singularity.
The universe seems to chug along like a smoking choo-choo train — almost like a perpetual motion machine that generates a brand new universe on the fading gasp of its last puff.
A contraction of mass into a singularity is a popular idea, but it never happens — not in this theory — except in black holes where all matter evaporates over time into the pure energy of Hawking radiation. In Penrose’s theory, only an infinite series of expansions following one upon the other from singularities indistinguishable by their metrics from maximally-expanded-universes will emerge.
It’s like a woman who gives birth to a daughter. The process repeats forever in the history of humans. Daughter buds from mother. Mother doesn’t contract to the size of a baby who then grows to become a new mother.
No, the process is continuous — one mother gives birth to a baby who grows to become a mother who births a new baby and on and on into an infinity of mothers that progress in a line of succession to the end of a time that has no end.
The universe expands until it becomes a singularity that expands into a new universe. The process never ends. There is no beginning and no end.
Roger Penrose at a conference. Photo by Biswarup Ganguly.
Does this idea by Roger Penrose resonate with the ring of truth to anyone? Roger has said that his idea is having some trouble catching on with bona-fide cosmologists.
For me, Roger Penrose’s idea feels like truth. His truth sets me free; everything falls into place; a weight is lifted from my shoulders when I think about what it means and why things might be the way they are.
Roger says that he is retired; the mathematics of his theory are worked out by his acolytes; they make predictions that are testable. One thing they predict are “Hawking points” or spots.
Hawking points are places where massive black holes have evaporated away every bit of the matter of the galaxies that fell into them. This radiation is concentrated; it will emerge to imprint the cosmic background of the universe that follows. The points or regions will spread to cover a circle in the sky that is four degrees across — close to eight times that of the Moon. Hawking points, if verified, will emit an energy that is ten to fifteen times more intense than the cosmic background radiation.
Hawking “spots” should be findable by humans. The radiation they represent bled into our universe from the universe that preceded and spawned them. Identifying Hawking spots will lend credence to the idea that a universe preceded ours and that another will follow in the far distant future — perhaps trillions of years from now.
Perhaps thirty candidates have been identified by recent satellite observations. The WMAP (Wilkinson Microwave Anisotropy Probe) satellite — illustrated above — and the newer Planck satellite have identified in the microwave background radiation (CMB) areas in space where the predictions of the Eon theory seem likely to be confirmed.
Roger claims that — absent mass — big and cold is equivalent to small and hot. The laws of thermodynamics hold in both worlds and are conformally equivalent. The mathematics are the same.
Roger Penrose has won 17 major awards in science; he has made major contributions in at least 30 areas of science and mathematics. The implications of his theory of conformal cyclic cosmology (CCC), if accepted by mainstream science, are worthy of a Nobel Prize.
I hope he lives long enough to receive it.
The video above, at 23:23, explains a consequence of the theory that dark matter (called erebons by Penrose) is required to make it work. Erebons are hugely massive compared to other atomic particles; they possess the mass equivalent of the eyeball of a flea. Sir Roger predicts that they decay and leave behind signals that will be confirmed by a focused analysis of data collected by the Laser Interferometer Gravitational-Wave Observatory LIGO.
Another interesting and rather strange consequence of the theory addresses the Fermi Paradox. From Wikipedia is the following reference:
”In 2015 Gurzadyan and Penrose discussed the Fermi paradox, the apparent contradiction between the lack of evidence but high probability estimates for the existence of extraterrestrial civilizations. Within conformal cyclic cosmology, the cosmic microwave background provides the possibility of information transfer from one Eon to another, including of intelligent signals within the information panspermiaconcept.”
NOTE: The members of the EDITORIAL BOARD are aware that many readers may not have studied physics or astronomy. They might be under the false impression that an article like the one that follows is going to be incomprehensible.
Nothing could be farther from the truth. Yes, those who have studied Maxwell’s Equations and Einstein’s theories will find his essay a kind of cakewalk. No doubt, eggheads will have issues with some assertions. Submit objections in comments — your head does not have to look like an egg.
WE, THE EDITORS wish to reassure readers — especially those who have yet to study math and science — that they have intelligence and imagination enuf to understand Billy Lee’s basic arguments.
We know Billy Lee. We work with him every day. He talks and tweets a lot but what does he really know?
Billy Lee likes to share notions with folks who can read. He claims it does no harm. For those who get “high” on science, Billy Lee included videos to make rabbit-hole hopping fun. Don’t be afraid to watch some.
THE EDITORIAL BOARD
UPDATE BY THE EDITORIAL BOARD:May 15, 2019; Victor T. Toth, the Hungarian software developer, author, and Quora guru of quantum physics wrote, “a photon has no rest mass, but it carries plenty of energy, and it has momentum. Its stress-energy-momentum tensor is certainly not zero. So it can be a source of gravity, it has inertia, and it responds to gravity. […] relativity theory predicts … twice the deflection angle for a photon in a gravitational field than the deflection of a Newtonian particle.”
Almost a century of experiments plus hundreds of upvotes on Quora by physicists seem to validate Victor’s argument.
The photon is known to be the only massless, free-moving particle in the Standard Model of physics. Other massless particles are the gluon, the graviton, and of course the Higgs, discovered in 2012 at CERN. Europeans plan to build a Higgs factory to learn more about them. Gluons mediate the strong force. They don’t propagate through empty space. No one has yet observed even a single graviton. Higgs give fermions like quarks their mass.
Photons have an electric and magnetic structure. They are electromagnetic pulses of energy that emerge from atoms when electrons drop from a higher energy state to a lower one. When electrons shed energy, a pulse of electromagnetic radiation is emitted — a photon of light.
Click pic for better view in new tab.
Photons of light can be emitted from atoms at different frequencies — colors when wavelengths fall within the narrow range that humans see. These frequencies depend on the energy of electrons, which exist in many differently configured shells (or orbitals) within both atoms and molecules.
Wavelengths of light felt but not seen are called infrared; other invisible frequencies fall into broad categories such as radio waves, microwaves, x-rays, gamma rays and so on — all require instruments to detect.
Electromagnetic radiation is the medium through which humans observe and interact with everything knowable in the universe. Humans live inside an electromagnetic bubble that they are struggling to understand.
One thing most physicists understand is that a disturbing 95% of the energy and mass of the universe comes from a source no one can see. Physicists observe the effects of invisible (dark) matter and invisible (dark) energy by measuring the unusual dynamics of galaxies and by cataloging the physical organization and expansion of the universe itself.
These measurements make no sense unless folks assume that a lot of gravitationally interacting stuff is out there which no one has yet observationally confirmed. The missing mass is not debris or dark stars. The most exaggerated conjectures about how much mass and energy is scattered among the stars won’t come anywhere near enough to explain forces that make galaxies behave strangely.
Dark matter and energy don’t seem to be electromagnetic. Dark matter, if it exists, interacts with the mass of two-trillion galaxies and seems to refract their emitted light. Humans are blind to all of it.
Scientists postulate matter they call WIMPS, MACHOS, axions, and erebons. Each has a few properties necessary to make the universe work as observed, but none have all the required properties except perhaps erebons, if Roger Penrose’s Conformal Cyclic Cosmology (CCC) is someday verified.
Space-saturating foam of micro-sized black holes is another idea some have proposed. The problem is that theorists believe tiny black holes might be too stable to radiate electromagnetic waves or gravity waves.
Micro-holes lie in a sort of crevice of invisibility — unobservable by LIGO and LISA style gravity-wave sensors, yet too massive for current and future particle-colliders like CERN to create.
Because micro-holes don’t radiate light at any frequency, light telescopes will never find them. No imagined interaction of micro-holes is able to generate gravity-waves with enough disruptive power in spacetime to be detected. The nature of physics seems to suggest that no technology can be developed to confirm or deny the black-hole foam idea.
Perhaps the same dilemma faces dark matter detection. We know it exists, but physics says we can never find it. It will always lie just outside our reach doing its work in an invisible universe no one will ever see.
Worse, not one of the proposed forms of “dark” matter has ever been observed or identified. It is likely that no experiment currently scheduled will detect dark matter, which many physicists believe is “out there” and makes maybe four parts out of five of all the matter in the universe.
It’s an incredible paradox for conscious humans to live in a universe where they are blind to almost every important thing that is happening within and around them.
Humanoids are like fish which spend their lives swimming in streams buried deep inside caves. Spelunkers like me know that certain species of cave fish have no eyes. They lack all ability to see their world — as do we, it seems. As intelligent as people are, they don’t yet build sensors capable of confirming their notions about what the universe might actually be at large scales or small.
Oh well… someday maybe new discoveries will make our predicament evaporate away. The universe will reveal itself to humans, as we knew it would. Our dream to fully understand reality will come true.
Some day.
Scientists have sensible mathematics to show that if electromagnetic particles are massless, they must travel at an upper limit, called “c“. Over decades, folks decided that this constant is the speed of a photon in a vacuum; they decided that photons have no internal rest mass and travel in vacuum at a speed limit — the speed of light.
The truth might be more mysterious. No one knows what the upper limit of “c” is, because no one knows with certainty that space is truly empty or that massless particles exist.
When physicists say that certain particles are massless, they sometimes mean that they don’t interact with the Higgs Field, which is known to give mass to fermions, like quarks. They don’t mean they don’t have energy, specifically kinetic energy, which is a form of inertial mass, right? They also aren’t saying photons don’t interact gravitationally. They do, in a special way described by the geodesics of spacetime in Einstein’s General Relativity.
More on this idea later.
British physicist Brian Cox wrote in his book Why Does E = mc2 ? that the question about whether photons have rest mass is not yet settled.
It’s true that more than a few reasonable people seem to believe that photons traveling freely in the vacuum of space are massless. If they truly are then the permittivity constant “ε” in Maxwell’s equation can be established for electro-magnetic particles (like photons).
The formula below is used to calculate the speed of a massless electromagnetic particle; it is thought to be a maximum speed.
For now, ignore the μ term. It is the permeability (resistance) of vacuum to infusion by a magnetic field, which is determined by experiment. It is sometimes called the magnetic constant.
Epsilon (ε} is the permittivity (resistance) of vacuum to an electric field. It is sometimes called the electric constant.
”c” is the so-called ”universal speed limit.” It is called the lightspeed constant.
These three numbers — μ, ε, and c — help to define the maximum velocity of an electromagnetic wave, which most people believe is the archetypal photon (of light). They assume that the photon packet travels at the maximum allowable speed in a vacuum.
A problem with this view is that no one has proved that space is free; or that space has no weight; or that photons have no rest mass; or that undiscovered particles formed from forces other than electricity and magnetism don’t exist. A few scientists have said that there might be no such things as free space or massless photons. It is also possible that space presents less resistance to other phenomenon yet to be discovered.
The idea that ”dark” matter and energy must exist to make the universe behave the way it does is compelling to many physicists. If true, it is possible — though light travels nearly 300 million meters-per-second — it is not traveling at the maximum speed of a generic, massless particle. The electric constant (ε)might need to be adjusted.
A decrease in the permittivity (resistance) of space (ε) — made obvious by inclusion of vast number of photons in the cosmic microwave background — drives ”ε” to be smaller and ”c” to be larger, right?
New particles, dark and as yet undiscovered, might do the same. The consequences could be significant.
Determining the upper speed of a massless particle requires a form of circular reasoning that is currently based on the measurement of the velocity of photons in a vacuum, which is called the speed of light.
The measured velocity of light in a vacuum is now an established constant of nature with a fixed value that doesn’t change regardless of the frame of reference. Modern labs have measured both the frequencies and wavelengths of various colors of light; multiplying the two numbers together always yields the same result — the speed of light.
Knowing the speed of light permits physicists to establish a value for ε by working backwards in the wave equation to solve for the electric permittivity of space. The value of “ε” falls easily from Maxwell’s Equations to a precision of 12 places.
It can’t be any other way. But is it the right way?
Here’s the problem: Physicists have measured mass in photons during experiments at the linear accelerator lab at Stanford University, SLAC.
In superconductors, photon mass has been measured to be as high as 1.2 eV.
Photon mass has been observed in wave guides and in plasmas.
Fact is, photons have inertial mass, which is a measure of their energy as calculated from their wavelengths or frequencies. In relativity theory, energy and mass are measured in the same units, electron-volts, because in the theory, mass and energy are equivalent.
Click this link to view CLOSER TO TRUTH interview with Raphael Bousso.
Cosmologist, Raphael Bousso, believes that empty space has weight, which is a measure of the cosmological constant, which is a measure of dark energy.
Space seems to be saturated like a sponge with something that gives it energy or force or weight if you will. The weight of empty space determines the size of the universe and some of its fundamental laws. Universes beyond our own with different weights of space can be larger or smaller and obey different rules.
Most physicists agree that photons become massive when they travel through transparent materials like glass, where they slow down by as much as 40%.
The problem is that these observations conflict with both the Heisenberg and the Schrodinger view of quantum mechanics, which is the most tested and confirmed model physicists have. Modern ideas seem to work best when photon mass is placed on the energy side of the mass-energy column. Otherwise, the presence of internal mass suggests that photons can be restrained to a defined size, which drives their momentums to infinity.
The truth is that it is not possible to prove that photons are massless. The stress-energy-momentum tensor in Einstein’s equation of General Relativity implies that photons can be both the source and the object of gravity. I’m referring to this tensor as “mass” and leaving it there for others to dispute. A rabbit hole for courageous readers to explore is the concept of pseudotensor, which this essay will avoid.
It is also not true that a photon can never be at rest either. Lab techs do unusual things with photons during experiments with lasers and superconductors — including slowing photons down and even stopping some (with supercooled helium-4). Right?
Another problem is the electromagnetic nature of light. The electric part of a light-wave carries enough energy to move an electron up and down. The magnetic part carries the same energy but its motion creates a force that pushes electrons outward in the same direction as the light. It’s why light-sails work in space. Oscillating magnetic fields push light forward. Otherwise, light might stand in one place and simply jiggle. But is light-speed the best magnetic fields can do?
Electromagnetism could be irrelevant in the search for an upper speed limit “c“, because “c” might prove to be the result of an unknown set of particles with properties outside the current boundaries of the Standard Model.
Massless particles, — undiscovered ones anyway — might not be electromagnetic. Humans might be biologically unfit to detect them; unable to measure their properties.
For those who might be rolling their eyes, remember that physicists claim that 95% of the mass and energy required to make the universe behave the way it does is missing. They call the missing stuff “dark” because they can’t find it. Excuse me should anyone catch me rolling my eyes.
Some theorists have speculated that “dark photons” might exist to help fill in the gaps. The popular TV show How the Universe Works actually repeated the idea in an episode of its latest series. The writers were probably referring to axions, which some physicists propose are similar to photons except that they have mass and are slower moving.
Photons are bosons. They are force carriers for electrons, correct?
Maybe folks should try to accept the notion that nothing in physics prevents bosons like photons from having mass or from taking on mass when they whiz over and through atoms and molecules (in glass and water, for example) where some physicists conjecture, they stimulate the release of polaritons in their wake. Jiggling electrons that lack the energy to jump states emit polaritons, which seem to add enough equivalent mass to photons to slow them down. Think of polaritons as light-matter wavelets.
Massive, gravitationally interacting photons are not required to be “dark.” If photons are the darkmatter, axions are unnecessary to solve certain problems both in cosmology and the Standard Model. No experiment will find them.
I mentioned that three other particles are presumed to be massless: the gluon, the graviton, and the Higgs boson.
To review, the gluon is not easily observed except in particle colliders where it lives briefly before decaying into other particles; it is confined among the protons and neutrons in the nuclei of atoms. The graviton, on the other hand, has never been observed. The Higgs boson was discovered in 2012. CERN plans to build a Higgs factory someday to explore its properties.
The only particle available to physicists right now that enables them to establish the permittivity of space and compute the velocity of massless particles is the photon.
That’s it.
If the photon has internal mass, i.e., rest mass, everything changes.
Let’s hop into a rabbit hole for a moment and go back a step: What if massless, non-electromagnetic particles mediate entanglement, for example? Wherever paired electrons are found, entanglement rules, right?
Everyone knows that entanglement violates laws of logic and physics. No one can make sense of it.
What if massless non-electromagnetic particles entangle the electromagnetic particles of the subatomic world? If they travel a thousand or ten-thousand times the speed of light, they will present an illusion over short planetary scales that entanglement is instantaneous. No instrument or lab will detect the difference.
What are the consequences if massless non-electromagnetic particles travel at a billion times the speed of light? Maxwell’s equations won’t apply to particles like these.
Because it seems that speeds of subatomic particles like photons are able to increase as their masses approach zero, it is possible that “c” could be orders of magnitude faster than the speed of a photon — that is, the speed of light — if it turns out that photons harbor tiny but significant rest masses.
I’m not advocating this notion. Let’s crawl out of the rabbit hole. I’m suggesting only that such a state of affairs is possible, because the assumption that photons at rest are massless — that internal mass of photons is always zero — though reasonable and desirable to justify models, is not yet settled according to some physicists.
And there is, of course, the phenomenon of entanglement which no one can explain.
Here’s speculation that should blow the mind of any thinking person: Could photons, if shown to have internal mass, be the stuff that make the galaxies move in the non-intuitive ways they do?
Yes, some physicists argue that the upper limit on the internal (rest mass) of a photon must be less than 10-52 kilograms, which is about 5.6E-17 eV for folks who think that way. (Multiply mass by the speed of light twice to make the conversion and divide by 1.60218E-19 Joules per eV.)
5.6E-17 eV doesn’t seem like much mass at all until folks realize that the minimum number of photons in the universe might be as high as 1090. This number is ten billion times the number of atoms in the universe. It means that the internal mass contribution from photons alone could easily exceed 1038 kilograms if the upper limit proposed by some is used to perform the calculation.
Do the math, anyone who doesn’t believe it.
Guess what?
Prepare for a letdown.
Based on the conjectured eVs, the mass of all material in the visible universe is in the neighborhood of 1053 kilograms. The video below will help the reader understand how this value and others are calculated. The mass of the visible universe turns out to be 1,000 trillion times more than the conjectured internal mass of all photons.
Think about it.
Is it enough mass to account for the galaxy anomalies seen by astrophysicists? To any reasonable mind the answer is obviously, no. But this conclusion is not the end of the story.
Those who study astronomy know that the outer stars in galaxies seem to move at roughly the same speed as the inner. Yet the galaxies aren’t flying apart.
By way of contrast, the planets in solar systems like ours travel slower the farther away they orbit from their sun. If Neptune orbited as fast as Earth, it would fly away into deep space.
A recalibration to account for the internal mass of photons of light (which seems to always be discounted) does not at first blush offer the gravitational heft that astrophysicists require to make everything on galactic scales fall into place.
The cosmic background radiation — which is nothing more than photons that decoupled close to the beginning of time — saturates the universe like vinegar in a sponge, right? It is distributed evenly across all space for as far as human-built instruments can see.
The CMB makes an annoying hum in radio telescopes no matter their focus or where they point. Photons with tiny internal masses or no mass at all will have no influence on the understanding by astrophysicists of how the universe behaves.
Neutrinos, which seem to oscillate between three (or perhaps four) as yet undetermined massive states, might at times take on values below the actual mass-value of photons — if photons turn out to be more massive than most believe. The laws of physics require that neutrinos less massive than massive photons, should they exist, must travel superluminally (faster than light). Agreed?
Several “discredited” observations have reported faster-than-light neutrinos, including the unexpected outcome of the infamous OPERA experiment, which inspectors eventually blamed on a loose fiber-optic cable that was ever-so-slightly longer than it should have been.
OK. It seems reasonable. Who can argue?
Scientists who believe that superluminal neutrinos actually exist don’t speak up, perhaps out of fear for their careers. They probably couldn’t get their opinions published anyway, right?
Click pic for better view in new tab.
Crackpot ideas that later prove valid is how science sometimes works. It’s how science has become the mess that it is — a chaos of observations that can’t make sense out of 95% of what is going on all around; a plethora of experimental results that don’t quite match the work of theorists.
The super-brilliant people who paint the mathematical structures of ultimate reality rely on physicists to smear their masterworks with the muds of perturbation, renormalization, and a half dozen other incomprehensible substrates to get the few phenomenon folks think they understand to look right and make sense. Theory and experiment don’t seem to match-up as well as some folks think they should more times than not.
A minor recalibration based on the acceptance of photons as quantum objects with tiny, almost unmeasurable masses will not change ideas about the nature of the universe and what is possible, because the upper-bound on photon masses might be undervalued — perhaps by a factor of billions.
Theorists like Nima Arkani-Hamed work on abstract geometries called amplituhedrons to salvage notions of massless particles while simplifying calculations of scattering probabilities in quantum mechanics. It seems to me like hopeless adventures doomed to fail. But in fairness so did Columbus’s exploration for new worlds.
To be a serious candidate for dark matter, a typical microwave photon should have an average mass of nearly .05 eV (electron volts), which is about 9 x 10-38 kilograms. If multiplied by the number of photons ( 1090 ), the photon masses add almost miraculously to become 85% of the theoretical mass of the universe.
(1E90)*(9E-38) = 9E52. (9E52) / .85 = 1E53 kg.
It’s the same number conjectured by dark-matter advocates.
To qualify for dark matter means that a typical or average photon must have close to one ten-millionth of the mass of an electron.
Only then does everything fall into place like it should.
Pull out the calculator, anyone who doesn’t believe it.
Einstein, in his famous 1905 paper on special relativity, showed that mass is equivalent to the energy of an object divided twice by a constant, which is “c” squared, right?
Later, he added a second term to the internal energy of a particle which is its inertial energy, pc2 . Simplified, this term equals hf for a massless photon. The total energy of any object is the square root of the sum of its internal energy and its inertial energy.
If Einstein is taken at his word, then the inertial mass of a photon is a function of its characteristic frequency — i.e. the inertial mass of a photon is equal to
where “h” is the Planck constant and “c” is the speed of light. The internal mass, should any exist, can be discounted.
An argument can be made from Einstein’s equations that the mass of a photon might be times larger. A factor of 1.414… won’t change the argument. It strengthens the point but is, in the end, not important enough to include in an article that is already overly long. Curious readers can review the reasoning in my essay General & Special Relativity.
If the average photon has an inertial mass of .05 eV, it requires that — all else being equal — the combined photon energy in a non-expanding universe would lie in the range of infrared light, a frequency in this case of 12E12 Hz, which is sometimes referred to as far-infrared.
(Set equivalent-mass equal to .05 eV (8.9E-38 kilograms) and solve for frequency.) The frequency approaches the lower energy microwave part of the light spectrum.
Note:For perspective, one eV is the energy (or mass equivalent) of a near-infrared photon of frequency 242E12 Hz, which approaches from below the higher-energy visible-light part of the light spectrum.
The mass equivalence of the inertial energy of 1E90 infrared photons is sufficient to hold the universe together to prevent runaway expansion caused by repulsion due to the gravity constant Λ in Einstein’s equation for General Relativity.
Do the math.
I know what some people might be thinking: Didn’t the 29 May 1919 solar eclipse, which enabled observers to confirm Einstein’s theory of General Relativity, demonstrate that photons lack internal mass? Didn’t Eddington’s experiment prove wrong Newton’s idea that photons, which he called corpuscles, were massive objects?
Maybe. Maybe not. Maybe internal mass isn’t necessary. There is enough energy in the inertial term of Einstein’s equation to yield the required mass.
Unlike massive particles where internal energy far outweighs inertial energy, for photons, inertial energy is dominant. Even if science admits to a small amount of internal mass in photons, it is their inertial energy that dominates.
I found a good mathematical argument for light mass on Quora by Kyle Lochlann, an academic in relativity theory. Here is the link:
Be sure to read comments to his answer — especially those who find math incomprehensible, which might be nearly everyone who reads my blog.
After all, Newton’s theory of gravity predicted that the light from stars would deflect near the Sun at only half what Eddington’s experiment clearly showed. Eddington’s eclipse proved Einstein’s theory — the geodesics of spacetime bend in the presence of massive objects like stars.
Many concluded that photons followed the geodesics of spacetime, because photons lacked mass equivalence of any kind. Newton erred about pretty much everything involving gravity and light, some said.
But their conclusion can’t be right, can it? Doesn’t their conclusion ignore what the math of Einstein’s formulas actually says?
Won’t it make more sense to say that the geodesics of spacetime constrain and overwhelm whatever internal and inertial mass photons might possess? Doesn’t it make more sense to convert the frequency-related inertial energy of photons to mass to better explain their behavior near objects like the Sun?
Evidence exists that light-mass is a thing and that it matters. Einstein included a mass-equivalence term for light in his tensors for general relativity. Frank Wilczek, MIT Nobel laureate, is famous for insisting that the mass of anything at all is its energy content. The energy of light is in its frequency, its momentum, which is a measure of its mass.
It’s true that light does not seem to interact with the Higgs field. Nevertheless, the energy of light seems to interact gravitationally with ordinary matter. The interaction is not measurable when photon numbers are small. When photon numbers are huge, perhaps it is.
A single photon in the presence of the Sun has no chance. When 10E90 photons saturate a space that is almost entirely devoid of matter, photons can shape a universe — especially when their number is 10 billion times the number of atoms.
It seems possible, at least to me.
According to data gathered by the NASA WMAP satellite, ordinary matter in the observable universe amounts to a little more than 1/4 of a neutron per cubic meter of space. It amounts to 253.33E6 electron-volts of mass. Everything else WMAP observed was “cold dark matter” and “dark energy”.
How many .05 eV photons does it take to flood a cubic meter of space with enough mass-equivalence to reduce the mass-energy of 1/4 of a neutron to 15% of the total? How many photons are required to sum to 85% of the energy WMAP attributed to “cold dark matter”? It turns out that the number is 34 billion photons per cubic meter.
The question is: how many photons are there?
The observable universe has an estimated volume in the neighborhood of 1E80 cubic meters, right? Yes, it might be as much as 4 times that number.
The lower-bound number of photons in the observable universe is 1E90. It might be ten times more.
It turns out that the number photons per cubic meter in the universe must be somewhere close to 25 billion. 25 is pretty darn close to 34. Since all the numbers are estimates with large margins of error, it’s possible that everything will fall into place as it should if and when the statistics of the universe are ever known with precision.
Could photons of light might be the “cold” dark matter everyone is searching for?
A single neutron has no chance when it is bathed in 136 billion .05 eV photons, which surround and envelop it on all sides from every direction. It makes a kind of quantum scale Custer’s Last Stand for random neutrons, right?
When scientists look at the universe today, they see an accelerating expansion. They see in the cosmic background radiation photons that have slipped from infrared into longer, less energetic microwave wavelengths which no longer have enough mass-equivalence to hold the universe together.
As light stretches into longer and longer wavelengths through interaction mechanisms such as Compton scattering and other processes (like the push of “dark energy” or the less popular gravitational tug of parallel universes), light frequencies and energies diminish.
Eventually, when the total of all light falls below an average frequency of 12E12, the equivalent mass of the 1E90 primordial photons loses its grip; it becomes unable to hold the universe together.
Near the beginning of time when photons were orders-of-magnitude higher in frequency than now, their stronger gravitationally-equivalent-masses pulled together the structures astronomers study today, like stars and galaxies.
But now scientists seem to be witnessing a runaway expansion of the universe. Light has stretched and dimmed into the microwave and radio-wave frequencies where its mass-equivalence is unable to hold together the universe as it once was.
Because we can’t detect it, isn’t it possible that dark energy and dark matter don’t exist? That is to say, the idea that dark matter and energy are necessary to account for observations is no more than a conjecture made necessary by a misbehaving universe of unusual galaxies. But direct observational evidence for dark matter and energy is the part of the conjecture that is missing. No one has ever seen any.
What astronomers are observing instead is faraway galaxies that existed billions of years ago when the mass-equivalent energy of photons was greater than it is now.
The intact universe of galaxies seen in the night sky today, which is photographed with high-resolution space-borne telescopes, is not up to date in any sense at all, except that it is the view of an ancient past that goes back almost to the beginning of time depending on how deep into space anyone looks.
Everyone who cares about astronomy knows it’s true.
To qualify as a candidate for dark matter means that a photon must have close to one ten-millionth of the mass of an electron. It seems like a reasonable ratio, right?
In the Standard Model, only neutrinos are less massive than electrons. No one knows what the mass of each of the three “flavors” of neutrinos is, but when added they are less than 0.12 eV — about 2.4 times the equivalent-mass of infrared photons and about one four-millionth of the mass of electrons. It seems possible to me that the mass of at least one of the flavors of neutrinos will be less than the conjectured equivalent-mass of an infrared photon packet.
Neutrons and protons are, by contrast, 2,000 times “heavier” than electrons.
I am asking working physicists to reexamine estimates that claim the mass of a photon can be no more than trillions of times less than the mass of an electron.
The claim can be found at the back of articles in science journals as well as in blogs across the internet. For me, the idea seems ridiculous on its face. The energy-equivalent mass of photons varies with frequency, but only the lowest energy radio wave photons can hope to approach the low equivalent-mass estimated in the latest publications.
Scientists might want to revisit the mass of a photon and the methodology of its measurement. The stakes are high, and science doesn’t have many options. Hope — like the energy of ancient photons — is fading.
Science would be served best if scientists started from scratch to reexamine every assumption and lab procedure. The search for dark matter has become an expensive and compulsive quest that seems futile, at least to me. Several costly experiments have reached disappointing dead ends, which are reviewed in the “VICE on HBO” video located near the start of this essay.
What if photons of light really are the dark matter, which is hiding in plain sight waiting to be discovered by anyone who dares to look at the problem with fresh eyes?
What if the delay between the observations of the CMB (cosmic microwave background) and the structure of the universe is a natural disconnect in time and space that misleads folks to believe that mass must be “out there”, when it has in fact long since dissipated?
From another perhaps opposite perspective, what if photons are instead stimulating emissions from virtual particles as they travel at fantastic speeds through the vastness of space? What if these emissions add mass to photons sufficient to bring them to the “dark matter” threshold, as they do in materials like glass?
Such a state of affairs would imply that not all photons travel the same speed in the so-called vacuum of “empty” space. It is a heretical idea, for sure — a can of worms, perhaps to some, but hey! — you can catch a lot of fish with a can of worms.
A photon is a packet of electromagnetic oscillations built-up from many frequencies. Superposition of these frequencies adds to give a photon its characteristic frequency from which its equivalent mass can be calculated. Right?
Use imagination to think of the many ways a higher “speed limit” that is mandated by the existence of massive photons might work to stimulate the interest of a space-traveling civilization to explore the universe, which ordinary folks begin to understand is more accessible, more reachable than anyone thought possible.
Consider the number of inexplicable phenomena that would make sense if particles thought to have zero internal mass don’t really exist, and photons, gluons, gravitons, and Higgs bosons aren’t the only ones.
Recalibration might save a lot of time and effort in the search for the putative missing energy and mass of the universe.
Should “dark” particles exist whose internal mass is less than that of photons, they will likely move at superluminal speeds that make them difficult to track. To influence stars, their number would have to dwarf photons. Such an idea strains credulity.
A counterproposal by Roger Penrose speculates that dark matter particles might have the mass of the eye of a flea; he calls them “erebons.” These particles are electromagnetically invisible, but their huge masses relative to other particles in the Standard Model make them gravitationally compelling.
Erebons decay; evidence for their decay should be showing up in data collected by LIGO detectors.
So far persuasive evidence for erebons has not been found.
For scientists and explorers, the access-barrier to a universe shaped and configured by massive photons will most certainly shrink — perhaps thousands to millions of times.
The stars and galaxies that people believed were unreachable might finally fall within our grasp.
Or — perhaps less optimistically and more cynically — the mass-equivalent energy of 1E90 photons might by now be so severely degraded that nothing can save a universe that has already come undone and flown away into an abyss that humans will never see.
The radiation-evidence from a catastrophe of disintegrating galaxies that has already occurred won’t reach Earth-bound viewers for perhaps billions of years.
Should humans survive, our progeny — many millions or billions of years from now — may “see” in the vastness of space a cold and diminished radio-wave radiation that hums in a soul-less vacuum devoid of galaxies and visible light. Microwave light will by then be nothing more than a higher-pitched, prehistoric memory.
Roger Penrose says that the fluid dynamics of an exhausted universe devoid of matter will become indistinguishable from the singularity that gave its start. A new universe will ignite from the massless, radiation-ashes of the old.
Human-nature forces us to want to know more; most folks want to search for and find the answers to the questions that will determine the fate of all life on Earth and in the vast stretches of spacetime that remain beyond our reach.
Is the universe within our grasp, or has it already disintegrated?
Twelve launch-capable space agencies (having as members about thirty countries) are, among other tasks, looking for alien life inside the solar system. They are exploring the four planets closest to the Sun: Mercury, Venus, Earth and Mars, which have three moons among them, and the five outer planets: Jupiter, Saturn, Uranus, Neptune and Pluto, which have one-hundred-and-sixty-three.
With so many moons and planets, the hope is that one of them will harbor life.
(Click pic to enlarge in new window.) Some recommend the Drake Equation to calculate odds that intelligent life which can communicate across space might exist elsewhere in the Milky Way Galaxy where our solar system is located.
Of the 166 moons and nine planets in the solar system, probes have managed to land on only five: Venus, Mars, Jupiter, Earth’s moon, and Titan (a moon of Saturn).
Just three moons are located in the Goldilocks zone where most scientists believe life has the best chance to take hold. Two orbit Mars at the outer edge of the habitable zone and are probably too cold and irradiated for life. The third moon orbits Earth.
(Click pic to enlarge.) Each column contains the orbiting moons of each planet (and a few other objects) inside the solar system.
Six moons in the solar system are comparable in size to the moon of Earth: Ganymede, Titan, Callisto, Io, Europa and Triton. All the rest are tiny with very little gravity — the force that can hold an atmosphere.
The twelfth largest rocky object in the solar system after Earth is Titania of Uranus, named for the Queen of the Fairies in Shakespeare’s Midsummer Night’s Dream. The moon is nearly a thousand miles in diameter. A 175 pound person on Titania takes on the weight of a newborn baby — a mere six pounds twelve ounces.
Few places in the solar system have enough gravity to hold a human securely, let alone an atmosphere.
No life has been found on any moon — or on any planet (except Earth) thus far. During the next several hundred years, humans will continue to look for life in the solar system should technology and civilization survive and advance.
The Kuiper Belt — which starts at Neptune and extends past Pluto — is a region that is home to an estimated 100,000 bodies of frozen methane, ammonia, and water.
Editors’ Note:(August 2016) The explorer spacecraft,New Horizons, flew by Pluto on July 14, 2016; it will fly by a Kuiper Belt object in January 2019.
Freeman Dyson — physicist, mathematician, and astronomer — has suggested that life might be pervasive in the Kuiper Belt and be easily detected once spacecraft get there. People wait and wonder.
Editors’ Note: (December 2018) Current analyses of data from the Pluto flyby describe a living, dynamic planet with a nitrogen atmosphere and a subsurface ocean. Portions of the surface are smooth with no signs of meteor impacts. Water-gushing volcanoes are common.
The solar system lies within a large disc-shaped galaxy called the Milky Way, which folks can see edge-on in the night sky should they travel out into the countryside away from well-lit cities, which tend to wash out vision.
It might surprise some readers to learn that no one really knows how many stars are in our galaxy. Credible astronomers believe the number to be somewhere between one-hundred and four-hundred billion — a huge range of uncertainty.
No one knows how many stars are similar to the sun. No one knows how many planets there are, or how many moons. Despite a lot of reporting and speculation, humans know almost nothing about the Milky Way.
Space is vast, and astronomers have few telescopes and satellites to accomplish the enormous job of taking it all in and cataloguing what they discover.
3.75 billion years from now, the Andromeda galaxy will collide with our own Milky Way. In this artist’s conception, Andromeda Galaxy is on the left; the Milky Way Galaxy is to the right.
Lack of knowledge about the details of our own galaxy helps to explain why it is difficult to understand the universe as a whole. When I first published this essay in late summer 2014, astronomers estimated that between a hundred and two-hundred billion galaxies populated the visible universe (the estimate is now known to be wrong).
Editor’s Note:On October 1, 2017 CBS News was among the first to report to the public that the Hubble space telescope had detected as many as two trillion galaxies — ten times more than previous estimates.
Two-trillion galaxies — and all the other objects in the universe that lie outside the local area of our own galaxy —are far away and too fuzzy for astronomers to know almost anything about them. The galaxies are out there, true, but the numbers are staggering. The small amount of data astronomers have already gathered is overwhelming scientists’ abilities to process and make sense of it all. And they are just getting started.
The Webb Telescope is scheduled for launch on 30 March 2021. Image is an artist’s rendition featured on Wikipedia.
Civilization is in the very first stages of placing sensors into space which eventually will help astronomers to learn more. One — the James Webb space telescope — is scheduled to launch sometime during the 2020s. Its purpose? — to tear down the 400-million-light-years-after-the-Big-Bang limit of the Hubble telescope.
Humans are going to be able to look back to the beginning of time, at long last. Understanding the process that brought us here is going to expand dramatically. Until then, the Drake equation (see illustration at beginning of the essay) and other speculative tools remain not much more than intriguing diversions.
New sensors like the Webb telescope will upgrade human understanding and bring a new realism that promises to sweep away much of the science-fiction people drink to satiate their thirst for ultimate knowledge.
Most articles, television shows, and movies that purport to portray the universe are (to risk overstating it) kind-of scammy. They seduce a gullible and curious public, which is hungry for answers about the universe that no one yet has.
The science community has a vested interest in public funding; they tend to go-along with dubious depictions to pander popular support. Claims that astronomers today understand fully the nature of the universe are ludicrous. The universe is vast. Much of its matter and energy that scientists believe is “out there” can’t be found — not yet anyway.
Most stars are too faint to see with unaided eyes. The closest star system to our Sun, Proxima Centauri, is too faint to see without a telescope.
Three out of four stars in the galaxy are probably red dwarfs. Red dwarfs burn essentially forever but are smaller and much cooler than the Sun, which makes them impossible to observe without special infrared detectors.
These infrared detectors are launched into outer-space beyond Earth’s atmosphere to avoid being blinded by the infrared heat radiating off Earth’s surface.
Proxima Centauri main star. Image by Hubble Telescope.
Red dwarfs seem to be emitting solar flares that are a thousand times more energetic and frequent than those generated by stars like the Sun. They emit light in frequencies not useful for plant photosynthesis — the basic life-support process on Earth.
It’s difficult to see how Earth-style life could get started and survive inside a red dwarf planetary system. No one knows what percentage, if any, of red dwarf stars have planets suitable for life.
Canon 85mm photo of Proxima Centauri three-star system by Skatebiker on English Wikipedia.
Red dwarfs live for thousands-of-billions of years. The Sun’s lifespan is eight to ten billion years — a tiny fraction of a red dwarf’s.
The Sun is similar to — who knows? — maybe one in five stars in the galaxy. It’s an optimistic guess, based on sampling and wishful hoping. Astronomers seem to agree that the Sun ranks as one of the largest stars in the Milky Way.
Statistical sampling of two-trillion galaxies argues that the Milky Way galaxy is also among the largest. A full 90% of all galaxies are smaller.
Calculations involving galaxy-motion and gravity suggest that when astronomers look at the cosmos, they aren’t seeing ninety-five percent of what’s out there. Physicists call the missing stuff dark energy and dark matter. Something that no one has yet been able to detect seems to be distorting the rotation of galaxies and disrupting the metrics of space-time.
The universe seems to be expanding, and the expansion is accelerating. Where is the missing mass and energy that drives the expansion? No one knows.
Perhaps parallel universes are stacked on every side against our own. They might swarm like bees around a hive. The gravitational pull of their enormous masses might be pulling our own universe apart. Galaxies inside our universe might be falling toward massive structures that lie outside our field of vision beyond a kind of event horizon.
Again, no one knows. It’s speculation. Today the expansion is described by a simple constant added into Einstein’s equation for General Relativity. A constant seems too simple, at least for me. It describes but doesn’t explain.
Einstein’s equation accounts for the accelerating expansion of the universe by including a term called the ”cosmological constant”. It is the Greek letter lambda ( Λ), which is multiplied against every member of the metric tensor, ”g” and then added to the left side of the equals sign, which is the side of the equation that describes the shape (curvature) of spacetime. The right side describes the distribution of mass / energy in spacetime.
Many of the galaxies that are visible from Earth are tens-of-thousands of times farther away than the farthest stars in our own galaxy, the Milky Way, which astronomers say is at least 100,000 light years across — a distance of six-hundred-thousand trillion miles. The galaxy is perhaps 200 light years thick, but its center is thicker still — about 10,000 light years.
If the Milky Way was shrunk to the diameter of a ten-inch plate, the plate would assume a thickness of a few human hairs but at the center it would thicken to the size of an egg-yolk.
To put these distances into perspective, the latest space probes, which travel at roughly twelve miles-per-second, are not capable of escaping the gravity of our solar system until they are mechanically slung by multiple encounters with planets to a velocity greater than 27 miles per second. At that speed, crossing the Milky Way takes nearly 700 million years.
What the Milky Way might look like if photographed by an extremely powerful telescope from the galaxy Andromeda, which is two-and-a-half million light-years from Earth.
The Milky Way is one galaxy in what astronomers have learned is a universe of two trillion.
Until scientists know more — and it could be decades or even centuries from now — prudence and the scientific method advise odds-makers to use the most conservative estimates, not the most optimistic, to speculate about intelligent life in the cosmos.
Until evidence accumulates that is more compelling than what is available today, plugging conservative numbers into the Drake equation, or any other speculative tool, always seems to give the same discouraging result — a number so small it might as well be zero.
No intelligent life that can communicate across space should exist in our galaxy or anywhere else in the universe. None. Yet, here we all are. It’s kind of mysterious, at least to me.
Substituting less conservative numbers yields a different result. Intelligent civilizations could number in the thousands or even millions. No empirical evidence supports such optimism, at least not yet.
Planets and Sun are shown to scale in this model. Distances are not. From left to right, largest to smallest: Jupiter, Saturn, Neptune, Uranus, Earth, Venus, Mars, Mercury, and Pluto. Pluto — recently demoted to the status of a ‘’dwarf planet” — has been re-argued for planet-hood by some cosmologists because the recent NASA fly-by showed Pluto slightly larger and more planet-like than previously thought.
Looking closer to home within our own galaxy, astronomers in 2003 discovered Sedna, which some think is another dwarf-sized planet orbiting far beyond Pluto.
Astronomers seem to discover new planet candidates every other month — Eris and Makemake are two more Pluto-sized objects out of hundreds that come to mind.
In 2014 Caltech astronomers presented evidence for another planet they called the ninth planet, which might be an object ten times the mass of Earth orbiting in a highly elliptical orbit at the farthest reaches of the solar system.
Regardless of what astronomers continue to discover, it seems likely that the Sun will always contain at least 99% of the mass in the solar system.
Earth is fortunate to orbit a star that is located in a less active region of space than many other stars in the Milky Way. The Sun lies safely between two spiral arms that are bright because of ongoing birthing of new stars. The location lies halfway from the center of the galaxy to its outer edge.
Click pic for better view of Earth’s position inside Milky Way galaxy.
Although stars are spread more or less evenly throughout the Milky Way, life-destroying cosmic events are less likely in regions where stars aren’t being born. Earth lives between bright spirals in a zone of relative inactivity, which has enabled the evolution of eukaryotic one-celled life to progress to intelligence, then civilization, and finally to space exploration over the past billion-and-a-half years.
Earth has a number of unusual features that make it a good candidate for highly evolved life. One important feature is its nearly circular orbit around the Sun, which helps Earth avoid the catastrophic temperature variations characteristic of the more egg-shaped (elliptical) paths of some of the other planets, like Mars.
Only the orbits of Venus and Neptune are more round than Earth’s. Mar’s orbit is five times less round. Of all the solar objects, only Neptune’s moon Triton is known to have for all practical purposes a perfectly circular orbit.
Another advantage for Earth is its 300-mile thick atmosphere of nitrogen and oxygen, 80% of which lies within 10 miles of its surface. Nitrogen and oxygen make up 99% of Earth’s atmosphere. These gases are opaque to non-electrically-charged, high-frequency light.
Nitrogen molecules block high-frequency, ultra-violet light while oxygen molecules, slightly smaller, block higher-frequency (shorter wave-length) x-rays and gamma-rays, which can be lethal to living organisms.
A three-atom form of oxygen molecule known as ozone helps to absorb in the upper atmosphere a dangerous-to-life, lower-frequency-band of ultra-violet light that nitrogen can’t block.
In the distant past — during the Carboniferous Period 300 to 360 million years ago — Earth’s atmosphere held 60% more oxygen than it does now, which provided more shade against damaging high-energy light. Dinosaurs and large insects — like dragonflies with three-foot wing-spans — thrived in the highly-oxygenated air they breathed.
It is one of the wonderful ironies of our planet that the oxygen which empowers the biology of life also defends it against the physics of life-destroying high-energy light and cosmic rays that are always raining down from outer space.
Without atmospheric moisture and greenhouse gases, Earth’s average temperature would fall to 100°F below zero.
In contrast to nitrogen and oxygen, which block high-frequency light from reaching Earth’s surface, carbon-dioxide, methane, and water vapor trap low-frequency light (infra-red light, or heat) and prevent it from radiating (or escaping) into space.
These green-house gases work like a blanket to help keep Earth at a constant temperature. Carbon dioxide, though rare, is heavy compared to oxygen and nitrogen. It tends to cling close to Earth’s surface where it is respirated by plants. Without atmospheric moisture, methane, and carbon dioxide the temperature of Earth would average 100°F below zero and vary widely between day and night as it does on the Moon.
Although water vapor and carbon dioxide make but a tiny fraction of the atmosphere, they have a significant impact on the planet’s ability to retain heat when their concentrations increase in the atmosphere. Exhaust from commercial jet aircraft, believe it or not, contributes greatly to the concentration of carbon dioxide and water vapor in the eight-mile highs of the atmosphere where these jets fly.
After the terrorist attack on 911, the government suspended all flights over the United States — including those by commercial aircraft — for four days. The skies over America cleared themselves of clouds and turned deep blue. Temperatures dropped.
I was amazed to observe these changes develop so quickly after all flying was suspended. It took about two weeks for aviation to return to pre-attack intensity. With the return of aviation, familiar weather patterns followed.
Unlike Earth, the planet Venus has so much carbon dioxide that its surface broils with heat. An explorer would have to hover thirty-seven miles above its surface to experience atmospheric pressures and temperatures similar to those on Earth.
By contrast, the atmosphere of Mars, though almost entirely carbon dioxide, is thin — only 1% as thick as Earth’s. Even so, near their surfaces the density of carbon dioxide is 15 times higher on Mars than on Earth — enough to grow plants and — if poisons in the soil can be avoided — terraform the surface should humans decide.
Although Mars is cold, especially at night, its carbon dioxide atmosphere enables daytime temperatures to sometimes reach 85° F during summer in its southern latitudes. The problem is that any plants that might grow in Martian soil must endure bombardment by dangerous-to-life high-frequency light and cosmic particles. Also, Martian soils are poisoned by perchlorates. The soil is useless for agriculture though perchlorates could be broken down to provide a source of oxygen.
I should mention argon, which is 1% of Earth’s atmosphere. It is formed by the radioactive decay of a rare isotope of potassium in Earth’s crust. It is transparent to infra-red heat, so it has no effect on global warming. It is heavy — like carbon dioxide — so it clings to the surface, but its small atoms, widely spaced, do little to prevent the escape of infra-red radiation.
Another asset that gives Earth an advantage for life is its large moon whose gravitational field acts like a vacuum cleaner to suck up cosmic-debris like asteroids and comets that might threaten to strike. Only Jupiter, Saturn and Neptune are similarly equipped.
Image courtesy of NASA
The moon stabilizes Earth’s tilt as it orbits the sun. The tilt is about 23.4°, which is why Earth has seasons. The tilt swings back and forth a few degrees over periods of 41,000 years. This variation is stable enough to permit life to survive and evolve despite the periodic generation of ice-ages.
Computer simulations of a moonless Earth show that with no moon to stabilize it, tilt variations could approach 90°. Dramatic destabilization has emerged in some simulations that make it difficult to imagine how advanced life could evolve and survive the climate extremes that might result from chaotic wobbling.
The Moon is receding away from Earth at a rate of almost two inches per year. It will take at least a billion years for the motion of Earth to destabilize. It seems that humans have time to figure something out.
Sadly, the sun gets brighter and less massive with each passing day. Over the course of a billion years, Earth will move farther from the sun to conserve its angular momentum. Meanwhile, the warming sun will overtake Earth’s great escape to evaporate its oceans and make the planet uninhabitable.
Looking at coming events from a more optimistic perspective, people can probably agree that a billion years is a long time. The species-human is likely to be extinct by then anyhow. So why worry?!
Another life-enhancing feature of Earth is its large, open, ice-free, salt-water oceans. Most scientists believe salt-water oceans provide safe habitat for evolving life.
Earth’s oceans make up three-fourths of the planet’s surface. In addition to providing a vast incubator for life, oceans reduce the probability that space-debris will fall onto land.
Odds are that debris will fall into the oceans where it is rapidly cooled and rendered harmless. Should debris strike land and throw up clouds of dust and ash to block the sun, the oceans provide a safety-blanket of thermal protection.
This photo of Titan’s surface is the only picture taken at the surface of a moon or planet that is farther away than Mars.
Besides Earth, only Titan — one of Saturn’s many moons — has open oceans (of liquid methane and ethane) on its surface. These oceans are more like shallow seas or lakes, estimated to be about five-hundred feet deep. Scientists think Titan has a salty sub-surface water ocean, as well.
NASA reported this year that another moon of Saturn, tiny Enceladus (310 miles in diameter), holds a six mile deep subsurface ocean — confirmed from Cassini fly-bys. Its over one-hundred geysers are what is populating Saturn’s E-ring. Data from the geysers indicate that the ocean is warm and salty and saturated with organic molecules. Analysis by Cassini instruments is on-going.
Of the moons of Jupiter, only Europa, Ganymede, and Calisto are thought to harbor salt-water oceans.
Europa is known to have a salt-water ocean, but it is covered by miles-thick ice.
Ganymede, the largest moon in the solar system, is believed to have a 500 mile deep salt-water ocean that lies beneath a crust 125 miles thick. The crust is thought to be a rock and ice mixture.
Scientists suspect that Callisto has a salt-water ocean, but it might be sandwiched between ice layers sixty or more miles beneath its surface.
Only the oceans of Earth are open, un-frozen, and deep enough (averaging three miles) to protect Earth against most encounters with meteors and other space-debris.
Fortunately for Earth, the solar system itself contains a massive structure that helps to protect and shield it from danger. It is Jupiter, the large and strongly gravitational planet, which like the moon pulls away space-debris that might otherwise zoom toward Earth to imperil all life. Observations suggest that comets strike Jupiter every couple of years. Comets that don’t strike are gravitationally deflected out of the solar system more often than not.
Another fortunate feature: Earth has, geologists say, a molten iron-core that emits a strong magnetic field to deflect life-destroying, electrically-charged cosmic particles, that have energies, some of them, approaching those of baseballs traveling sixty miles-per-hour. Cosmic particles accelerated the process of ripping away Mar’s atmosphere. Without a magnetic field the Mars atmosphere is defenseless against cosmic erosion.
As for Earth, high energy particles that do manage to blast through it’s magnetic shield (magnetosphere) are often scattered and rendered harmless — fortunately — by collisions with the oxygen molecules in Earth’s dense atmosphere.
One exception is muons, which are byproducts of particle collisions high in Earth’s atmosphere that are energetic enough to burrow down to hundreds of yards beneath Earth’s land surfaces and oceans. In rare heavy bombardments at high altitudes, muons can increase risks of cancer and cataracts to pilots and their passengers. Muons are like electrons except that they are 207 times heavier and much shorter-lived.
Sun’s solar wind deflected by Earth’s magnetosphere. NASA art.
The magnetosphere is strong enough to deflect the solar wind, which can strip away all or part of the atmosphere of any planet that lacks one (like Mars).
The magnetosphere is effective and strong, because it is huge and surrounds Earth out to five Earth-diameters on the side facing the sun; one-hundred Earth-diameters on the side opposite. In any small area of space, though, a simple bar-magnet is fifty times stronger.
The solar wind isn’t all bad. As it radiates outward from our Sun, it forms a huge magnetic bubble called the heliosphere that extends 3.5 billion miles past the Kuiper Belt.
Inside this Sun Bubble the rest of the solar system is protected from massive cosmic particles that pour in from the two trillion galaxies of stars that make the universe. The Sun bubble deflects to shade our solar system in relative safety.
The heliosphere of the Sun works together with the magnetosphere of Earth and its oxygenated atmosphere to break up and knock away the vast majority of cosmic particles (high-speed protons and atomic nuclei) that would otherwise rip Earth-life to shreds.
Absent the magnetosphere, life could evolve safely only in the deep oceans or far below the surface of Earth. Stated differently: a strong, protective magnetic field is essential for the survival of surface life on any planet.
Large solar flares are known to have enough energy to kill exposed astronauts. It’s one of many reasons NASA doesn’t send people to Mars, which lacks a magnetosphere. Mars is under relentless bombardment of atomic particles that can damage the atoms and molecules in the cells of a human body.
All planets have magnetic fields of various strengths except Venus and Mars. The iron in the core of Mars is believed to have frozen solid, or nearly so, hundreds of millions of years ago, which helped force its protective magnetic field to collapse.
Venus retains its molten iron-nickel core, but the planet lacks tectonic action in its crust. The heat of its core can’t escape through its surface, which prevents in its molten center the emergence of the turbulence essential to make a planetary dynamo of sufficient power to rev-up a magnetosphere.
It’s a shame that both Mars and Venus lack magnetospheres, because both planets have attributes that might otherwise make them good candidates for life.
Earth’s core is huge — it rivals the entire planet of Mars in size. The inner third of the core — the center — is already frozen solid. It is believed to be pure iron. The core is freezing itself solid from the inside out.
The rest of the core is hot liquid iron and nickle, mostly, with some sulfur and other impurities mixed in. It circulates in complex eddies, which generate the magnetic fields that protect Earth by deflecting the solar wind.
The flow of currents in the molten metal is made stable and more reliable by the unusual plate tectonics peculiar to Earth. Gaps in Earth’s crustal plates allow heat to escape from volcanic valves, which help to maintain a controlled roil in the eddy currents to produce the dynamo that drives its magnetosphere.
The only moon known to have a magnetic field is Jupiter’s Ganymede. Jupiter itself harbors a field fourteen times more powerful than Earth’s. The giant planet’s four largest moons orbit inside it, where they are protected from the solar-wind and low frequency (low-energy) cosmic particles. By contrast, Mercury’s magnetic field is one-hundred times less powerful than Earth’s.
Despite these several advantages for sustained evolution of life, Earth has the apparent disadvantage of a volatile climate which, scientists believe, has turned cold and icy during several extended periods. I mention this volatility to remind people that the circumstances that have enabled life to advance to the technological civilization of today are complex and not obvious.
Until scientists are able to tease out of history what is actually important and significant for the development of advanced life, no one can know what the rest of the universe may have in store — unless we travel out into space and explore it.
I want to believe: we will find the way.
Here’s the problem. The closest stars to the Sun are twenty-five trillion miles away. To escape the solar system, engineers must build spacecraft that can accelerate to 27 miles per second. At that speed the nearest stars, Proxima Centauri, and the binary star system, Alpha Centauri, are 30,000 years distant.
How are humans going to explore the universe? How are we going to answer the questions about our place in the cosmos, when we can’t travel to the nearest stars?
There are trillions of stars, most of them many millions of times farther away than these, our closest neighbors. It seems hopeless that anyone will ever know the answers to the basic questions about the universe that so many are asking.
Still, in my heart of hearts, I want to believe we will find a way.
Billy Lee
Editors Note:November 2017; NASA announced that the latest count of galaxies might be as high as two trillion. The velocity required by spacecraft to escape the Milky Way galaxy from Earth (our planet is 25,000 light years from the galaxy center) is 342 miles-per-second. At this velocity the nearest galaxy — Andromeda — is a flight of 2.28 billion years. There are two-trillion galaxies more!
It doesn’t really matter. Here’s why:
The Parker Solar Probe scheduled for launch in 2018 will require seven gravity-assists from Venus over a period of six years to reach a velocity of 120 miles-per-second before it embarks on a 2024 suicide mission into the outer atmosphere of the Sun.
Venus and the Sun combined can’t accelerate the Parker Solar Probe to the galaxy-escape velocity of 342 miles-per-second.
Minus gravity-assists, the fastest vehicles in development today by space-flight engineers will accelerate to speeds less than 27 miles-per-second — the escape velocity required to exit the solar-system. Without gravity assists that take years to rev-up, we humans can’t leave our own solar system, which is arguably the tiniest imaginable fraction of the Milky Way galaxy.
The good news is that life-forms in far-away solar systems face the same obstacles. If they are hostile, humans can be assured that they will have a difficult time getting here.
The bad news is that humans are trapped. The Milky Way Galaxy is a prison. We can’t escape, at least not yet; most likely, not ever. The escape velocity of the Milky Way Galaxy from Earth exceeds 340 miles-per-second — nearly three times the velocity that the Parker Solar Probe will be traveling when it is finally able to bury itself inside the Sun.
The visible universe is big. Most scientists believe the invisible universe — the universe no one can see — is really big.
If the Universe shrunk down to where Earth became the size of a period at the end of a sentence, how big would it be?
When I was a kid, questions like these fascinated me; what harm is there to revisit a few?
About 100 dots the size of the period at the end of this sentence must be strung together to make an inch. We can imagine shrinking Earth to the size of one of these dots, then plugging-in the numbers to calculate the scale of everything else. It turns out that the observable universe shrinks to a diameter of about two light years.
Since a light year is nearly six-trillion miles, the universe is fantastically big. At this reduced scale, the size of the universe remains pretty much incomprehensible.
In this pic, the Sun sits directly behind Saturn, which is backlit by it. Earth is the tiny dot inside the illustrator’s circle to Saturn’s left. Earth is hundreds-of-millions of miles into the page—behind the gas-giant and its rings. Click pic to enlarge in new window.
When Earth becomes a period (or dot), the Sun shrinks to close to an inch in diameter — or 2/3 the diameter of a ping-pong ball. [regulation ping-pong balls are 1.575″ in diameter] The dot-sized Earth orbits 10 feet away. Neptune, the farthest planet, is smaller than a BB — a tiny ball of methane ice almost one football field distant (97 yards).
The distance light travels in a year shrinks to 120 miles — a speed approaching ¼ inch-per-second. The distance to Alpha Centauri, the nearest Sun-like star, shrinks to 500 miles. The star Alpha Centauri shrinks to a ball that is only slightly larger than our under-sized ping-pong ball-sized Sun.
Think about two 1″ diameter ping-pong balls separated by 500 miles. Imagine trying to commute between these balls when the top speed is less than ¼ inch-per-second. Of course, nothing travels at the speed of light. At speeds typical of spacecraft today, it takes 100,000 years to reach Alpha Centauri.
At the scale where Earth is a dot, one might wonder what is the size variation of stars. It turns out that most suns (stars) in the universe range in size from a grapefruit to a pea.
Of course, outliers exist like Deneb, the blue-white supergiant visible in the Summer Triangle. At 203 times the size of the Sun, it shrinks to 17 feet or so in diameter depending on how accurately anyone cares to scale things. Rare super-giants are larger; some are 75 feet or more in diameter at this scale. But in the Milky Way Galaxy, our undersized ping-pong Sun is one of the larger stars.
Is there another way to grasp how large the universe is?
The Milky Way Galaxy — the Sun orbits its center in the space between two of its outermost spiral-arms — is 100,000 light-years across. If the Milky Way was reduced to the dimensions of a coin the size of a quarter, the visible universe (the universe that can be seen with telescopes) would collapse into a sphere of space 15 miles in diameter.
In such a reduced sphere of space, large galaxies become the size of Frisbees but outliers like the mammoth IC1101 are the size of truck tires. The smallest galaxies shrivel into mere grains of sand. Distances between galaxies diminish to 100 feet or so but variations are huge because galaxies tend to cluster together to form groups, which are separated from one another by vast distances.
At this scale, astrophysicists say that the presence of galaxies that cannot be seen (because the distances between our Milky Way Galaxy and the farthest-away galaxies recede faster than the speed-of-light) makes the entire universe, visible and beyond, a minimum of 50 miles in diameter. Light, believe it or not, stands still at this scale. No human observer during their lifetime would notice any movement at all of light or any other phenomenon.
Even the faster-than-light expansion of the universe would be unobservable.
According to physicist, Stephen Hawking, it takes a billion years for the universe to expand by 10%. Five miles (10% of 50) during a period of one billion years is 7 billionths-of-an-inch per day. During a human lifetime the expansion adds to 2 thousandths-of-an-inch (.002″) — less than half the width of a strand of hair.
At the scale where the Milky Way Galaxy is the size of a quarter, the entire universe would appear to be frozen solid during the span of a human lifetime.
Artist’s view of water molecules. Molecules are the smallest structures that can be directly observed (with the help of special sensing instruments and computer generated enhancements). Molecules are the building blocks of all things.
What about tiny things?
To examine the scale of the very small we can imagine enlarging molecules, the building blocks of all things, to the size of the same period-sized dots.
How tall might an average person be? After again plugging in the numbers and calculating, it turns out that a human stretches to a height of 1,000 miles. The eye expands to an orb 15 miles across.
Molecules are small. But at this imagined scale — a scale that requires sophisticated instruments to discern — individual molecules become visible. They grow to look like little dots separated by distances only a bit larger than the dots themselves. Sadly, no one can see the individual atoms that make up the molecules. Even at this enlarged scale, they are too small.
No instruments or microscopes can be constructed to enable anyone to “see” atoms. Physicists believe atoms are real because they see the evidence left behind as their debris moves through the detection mediums of cyclotrons, colliders, and other sensors.
Since 1981 physicists have used scanning tunneling microscopes (STMs) to “feel” the forces of atoms with “nano” probes. A computer algorithm plots the forces and creates pictures of atoms, which with this method look like stacked billiard balls.
Billiard balls is not what quantum objects “look” like because quantum objects can’t be seen using human vision but at least scientists can prove that lumps of energy exist and are arranged in patterns that can be analyzed. It’s a start. It’s something.
Models of atoms studied in science class at universities around the world are contrived to help make sense of the results of many experiments. They are somewhat fanciful.
As for living cells — the basic building blocks of all biology — people are able to observe them under magnification because every cell is built-up from many billions of molecules. Some human cells have trillions. The size of a typical cell at the scale where molecules are expanded to about the size of three-dimensional dots is about 60 feet across.
Artist’s large scale view of the universe.
The gulf between the very large and the very small strains credulity but science says it’s real. When thinking about it, I am overcome by wonder and the despair of not knowing why or how.
Theoretical physicist Nima Arkani-Hamed has said that the gulf between the very large and the very small is required to balance the force of gravity against electrical forces in celestial objects like planets. He has pointed out that the ratio of the surface area of a typical atom and the surface area of a typical planet mirrors the difference between the two forces.
Nima Arkani-Hamed, one of the world’s top theoretical physicists, makes a point.
The huge difference between the force of gravity and the force of electricity makes the gap between the very large and the very small essential in a universe that works like ours; the difference in scale is necessary and inevitable, Nima has said.
If the ratio moves too far from this balance — if the surface area of an object gets too big — gravity will overwhelm the electrical forces that hold the atoms apart to cause the object to light up from a process called fusion, which can leave behind a shining star. A much larger object will collapse to become a black hole.
Why is the gap between the force of gravity and the electrical force as vast as the difference in surface area between a typical planet and a hydrogen atom? How did the ratio get that way?
No one knows. The values of the forces seem as finely tuned as they are arbitrary. Nima Arkani-Hamed and others are working to understand why.
Another mystery: Why is the universe so big?
Even Nima Arkani-Hamed admits he doesn’t have the answer — not yet, anyway. Perhaps the answer lies in the geometry of spheres, which is the basis of the Billy Lee Conjecture discussed in the essay Conscious Life.
Speaking of spheres, everyone knows that billiard balls are polished smooth, right? Earth, after being shrunk to the size of a pool ball, is smoother and less blemished; more perfectly round. Exhale on a pool-ball to create a mist that is 10 times deeper at scale than the deepest ocean on Earth.
Do the math.
It’s true.
As a child my nightmare was of an enormous whale crushing a tiny flower. A psychologist told me that the whale was a parent; I was the flower.
Maybe.
But the universe captures my nightmare. It’s really big and I am so very small, helpless, and lost within its vast expanse.
times larger. A factor of 1.414… won’t change the argument. It strengthens the point but is, in the end, not important enough to include in an article that is already overly long. Curious readers can review the reasoning in my essay 
