“One of the greatest discoveries of the century is based on these things and we don’t even know what they are, really.”
The uncertainty of science: New research suggests that astronomers have little understanding of the supernovae that they use to estimate the distance to most galaxies, estimates they then used to discover dark energy as well as measure the universe’s expansion rate.
The exploding stars known as type Ia supernovae are so consistently bright that astronomers refer to them as standard candles — beacons that are used to measure vast cosmological distances. But these cosmic mileposts may not be so uniform. A new study finds evidence that the supernovae can arise by two different processes, adding to lingering suspicions that standard candles aren’t so standard after all.
The findings, which have been posted on the arXiv preprint server and accepted for publication in the Astrophysical Journal, could help astronomers to calibrate measurements of the Universe’s expansion. Tracking type Ia supernovae showed that the Universe is expanding at an ever-increasing rate, and helped to prove the existence of dark energy — advances that secured the 2011 Nobel Prize in Physics.
The fact that scientists don’t fully understand these cosmological tools is embarrassing, says the latest study’s lead author, Griffin Hosseinzadeh, an astronomer at the University of California, Santa Barbara. “One of the greatest discoveries of the century is based on these things and we don’t even know what they are, really.”
The key to understanding this situation is to maintain a healthy skepticism about any cosmological theory or discovery, no matter how enthusiastically touted by the press and astronomers. The good astronomers do not push these theories with great enthusiasm as they know the feet of clay on which they stand. The bad ones try to use the ignorant mainstream press to garner attention, and thus funding.
For the past two decades the good astronomers have been diligently checking and rechecking the data and the supernovae used to discover dark energy. Up to now this checking seems to still suggest the universe’s expansion is accelerating on large scales. At the same time, our knowledge of supernovae remains sketchy, and thus no one should assume we understand the universe’s expansion rate with any confidence.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
The uncertainty of science: New research suggests that astronomers have little understanding of the supernovae that they use to estimate the distance to most galaxies, estimates they then used to discover dark energy as well as measure the universe’s expansion rate.
The exploding stars known as type Ia supernovae are so consistently bright that astronomers refer to them as standard candles — beacons that are used to measure vast cosmological distances. But these cosmic mileposts may not be so uniform. A new study finds evidence that the supernovae can arise by two different processes, adding to lingering suspicions that standard candles aren’t so standard after all.
The findings, which have been posted on the arXiv preprint server and accepted for publication in the Astrophysical Journal, could help astronomers to calibrate measurements of the Universe’s expansion. Tracking type Ia supernovae showed that the Universe is expanding at an ever-increasing rate, and helped to prove the existence of dark energy — advances that secured the 2011 Nobel Prize in Physics.
The fact that scientists don’t fully understand these cosmological tools is embarrassing, says the latest study’s lead author, Griffin Hosseinzadeh, an astronomer at the University of California, Santa Barbara. “One of the greatest discoveries of the century is based on these things and we don’t even know what they are, really.”
The key to understanding this situation is to maintain a healthy skepticism about any cosmological theory or discovery, no matter how enthusiastically touted by the press and astronomers. The good astronomers do not push these theories with great enthusiasm as they know the feet of clay on which they stand. The bad ones try to use the ignorant mainstream press to garner attention, and thus funding.
For the past two decades the good astronomers have been diligently checking and rechecking the data and the supernovae used to discover dark energy. Up to now this checking seems to still suggest the universe’s expansion is accelerating on large scales. At the same time, our knowledge of supernovae remains sketchy, and thus no one should assume we understand the universe’s expansion rate with any confidence.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Z man said:
The key to understanding this situation is to maintain a healthy skepticism about any cosmological theory or discovery…
I could not agree more. The more we learn, the less we know. Each model they prove to us that the theory is either wrong or the math is insufficient to the problem.
So they use their best guess as if it was fact. They can tell how fast a galaxy is moving away from us by the light frequency (450 nm blue or 700 nm red). Don’t both of these frequencies travel at the same rate? Can’t magnetism and gravity also cause resistance and change the frequency of light?
With all those galaxies out there colliding (including our own with Andromeda) you would think the universe is contracting because of the obvious evidence. Are we expanding? Perhaps, maybe all the galaxies are expanding in the same direction… perhaps we are not the center of the universe as everyone thinks… just one more galaxy, in a wall of galaxies that was once a blast wave from the beginning. I suppose my guess is as good as anyone else’s.
During the solar eclipse, ocean will experience unusually high tides directly under the sun/moon. Gravity? The opposite side of the planet will experience the same high tide minus the 3% difference. Antigravity? The earth’s oceans, at 90° to the sun/moon, will have a below average ocean height. A intensifying of earths gravity? Causing unusual low tide?
I have confidence that when they explain this yet unexplainable phenomenon on a planet in freefall, they will have a better grasp on what controls the movement of galaxies without the need of faith in an invisible, intangible, incredibly dense mass which increases gravity and yet is repulsed by the center of the galaxy… spiritual substance of dark matter.
Max wrote: “With all those galaxies out there colliding (including our own with Andromeda) you would think the universe is contracting because of the obvious evidence. Are we expanding?”
Try not to confuse the expansion of the galaxy in general with the motions of galaxies within each cluster of galaxies. The obvious evidence is that the universe is expanding. It is the details that are called into question by the new research that Robert is talking about.
https://www.youtube.com/watch?v=t9276Lk_Ipg (4 minutes)
The results of the new research is that we can no longer be sure that the rate of expansion of the universe is increasing. We may not need the hypothesized “dark energy” to explain what we see in the universe, because it probably is not what we think we are seeing.
Max wrote: “I have confidence that when they explain this yet unexplainable phenomenon on a planet in freefall”
Actually, tides are a well understood phenomenon. We know why and how it works, and dark matter is not involved.
https://www.youtube.com/watch?v=KlWpFLfLFBI (10 minutes)
However, “We” are not at the center of the universe. That honor rests with me. I am at the center of the universe, no matter where I go. The universe revolves around me.
That could have been my oversized (yet most humble) ego talking, but since there is no center to the universe, we could consider each point to be the center of the universe. You, dear reader, and I may not be the center of the world, but we are each at the center of the universe. This is one of the things that makes science so much fun.
Love me some Cosmology stuff!!
Max–
You raise some very interesting points, but I can’t address them very deeply right now.
Referencing–colliding galaxies; the Milky way is going to crash into the galaxy of Andromeda, but all our other “close” galaxies are moving away from us.
Referencing– the “center of the Universe;” there is no “center,” and were are not it.
Referencing– “expanding space;” it’s the space between galaxies that is expanding
Pivoting back to distance–
There is a series of short (<15 minutes each, 11 total) lectures from Caltech which are very enlightening, regarding "distance."
These provides an excellent (and highly understandable) primer on distance, starting with parallax measurement and moving outward. (The whole "galactic distance ladder" 'thing.)
He goes over all the methods, when they can be used or not, pro/cons for each, and how they interrelate with each other.
Lecture-6 Galaxies and Cosmology –
Stellar Distance Indicators
https://youtu.be/ddc2SZwJy7Y
(14:41)
(Lecture 7 covers "distance indicator relationships," and #8 covers "supernova standard candles.")
Max-
reference your ponder:
“Can’t magnetism and gravity also cause resistance and change the frequency of light?”
Photons have no Mass, but they act as if they do. So, yes– gravity plays with frequency.
There is a relationship between Planck’s Equation E=hv, [(Planck’s constant)*(Frequency)] & Einstein’s E=(m)(c-squared.)
I want to say, “frequency is a conserved quantity,” but I only play a particle physicist on the Interweb, so I might be botching that statement. That aside, this is well understood and does not require “dark” anything.
[tangentially interestingly; Einstein’s metric requires 10 components to describe conformal space-time, 9 of which specify location and 1 specifies Mass. Photons & magnetic fields don’t have Mass and only require 9 components to fully describe. For this I’d reference anything from Dr. Roger Penrose.]
back to red-shifts–
Quantum Mechanics 2:
Basic Concepts (15 of 38)
Gravitation Redshift: 2of2
https://youtu.be/raMaH55eYPg
(6:44)
-all Newtonian Math, logically presented.
(Highly recommend this entire series, it’s lengthy, but each concept is delivered in short doses. )
Edward-
Good stuff.
Great Topic.
as I’m want to do– this reminds of a tune
“A Dream within a Dream”
Alan Parsons Project [“Tales of Mystery and Imagination; Edgar Allan Poe” Narration: Orson Welles]
https://youtu.be/VZyNKrYo9I4
Yes, definitely agree with Mr. Z. on the – “The key to understanding this situation is to maintain a healthy skepticism about any cosmological theory or discovery…”, thought.
Personally, I highly enjoy the Cosmology stuff, and it is all fantastical. I’m also well aware its all subject to revision and I’m leery of the physicists who push stuff in popular media for dubious reasons and personal benefit, or make absolutist declarations.
I’m perfectly OK with uncertainty in Cosmology.
Dr. Roger Penrose addressed themes of caution & healthy skepticism in his recent book, “Faith, Fashion, and Fantasy in the New Physics.” Highly recommend any of his lectures, and his thoughts on “chasing fads” in physics is enlightening.
Cool factoid:
“We have 54 galaxies within a 3 million light-year spherical distance from us.”
That is mind-boggling unto itself. I wouldn’t be surprised if we are missing a few Fundamental Factoids and/or aren’t understanding completely the ones we think we do.
The Size of the Universe (4 of 6)
“Our Local Group of Galaxies”
Michel van Biezen [this guy is good, bow-tie, sharpie, and foreign accent!]
https://youtu.be/MiW1ybxb8NM
(5:17)
As our universe expands, gravity weakens with the cube of distance, meaning momentum has less force constraining it. Thus, acceleration of our universe does not require another force, e.g. dark energy. It’s possible that something is different about the non-observable part of the universe that affects expansion, but I think it very unlikely. Also possible are unknown quantum effects involving the nature of space itself that interact with matter on a large scale.
I just can’t believe in a(there be dragons) dark energy.
It would have to be classified as a weak force.
It can not overcome or in anyway effect the 4 known forces of the standard model.
Nor in anyway effect matter inside a galactic cluster.
But as soon as you put it out in interstitial space it becomes so powerful it can move galactic clusters like dust in the wind.
But yet none of that same force ever comes from the opposite side of those “expanding” galaxies to slow them down.
And to just magically create this dark energy you only need and area with an infinitesimally low level of gravity and boom, dark energy starts to erupt from the ether.
Or maybe its not an energy but space itself that erupts out of those magic areas pushing everything away.
Or with gravity so low in those areas space just starts to stretch.
Or we could assume the universe is spinning and angular momentum is finally over coming gravity across those vast distances.
pzatchok:
Nice comment, logical thought. You’ve pointed out more problems with dark matter then the creation of dark matter solves. Just because humans can imagine a substance that violates the laws of physics doesn’t mean nature will do so. I’m a big fan of Ochman razor, The simplest explanation is usually the correct one.
You wrote; Or we could assume the universe is spinning and angular momentum is finally over coming gravity across those vast distances.
I like that better than my bast wave from the beginning! It’s more in keeping with what we find in the formation of galaxies. They could be a miniature version of the universe itself.
Dave Williams:
I just read that even though we can only see 14 billion light years in each direction, (200 billion galaxies) The energy created at the moment of the big bang (as the theory goes) was expanding outward at the speed of light achieving escape velocity as it was becoming matter with mass. It is thought that 90% of the universe accelerated away at such a high speed that the universe should be as much as 250 billion light years across,100 sextillion galaxies. pulling at the galaxies left behind in their direction. That stuffs over my head. I suppose that an infinite universe by definition has no size.
Quantum flux popping in and out of existence in the vacuum of space driving galaxies to expand apart worries me. Anything that can be created from nothing can just as suddenly stop or reverse, destroying the nothingness allowing the universe to collapse on itself. I prefer a static universe with action and reaction and no unseen variables.
Edward:
Yes, the universe is expanding… Except where it is not. Since we see clusters in every direction we look, perhaps gravity is the kryptonite to the theory and prevents the space between these galaxies from expanding.
In the 1st link you provided, it made me laugh out loud when he was talking about the discovery of red shift with Andromeda, a galaxy heading towards us. How very ironic. Of course they went on to say that other galaxies are more shifted into the red spectrum the further away from us they are. The problem is their visual they provide (which is the same visual on Wikipedia) is a fake. The colors of the spectrograph are identical, like a rainbow on a sheet of paper that was cut in half. They shifted the spectral lines on the example half without regard to the actual wavelengths of the light. The spectral line on the border of the green color for example was shifted over to the center of the green in the sample. Not cool.
There are different theorys and lines of thought concerning this. One that I had not heard of before is explained at great length in the comment section of the topic article that Zimmerman posted above. He calls it “tired light”.
Electrons from a distant galaxy must pass through a great many regions that could be full of clouds of polarized gases and magnetic clusters of nebula dust. The solar wind of every star it passes, along with its magnetic field to slow it down. The electro magnetic field of the electron next to it on the same journey or the electrons coming at it from all directions slowing each other with their light pressure or electromagnetic field distortion. Radiation from the galactic winds and the ever present big bully of interstellar travel, cosmic radiation. It’s a wonder that we can see any light at all from distant galaxies. Tired light indeed.
Other theories include subatomic particles called “Cosmic flux” that winks in and out of empty space that theoretically provides some of the missing mass of the universe may slow light down. (if it’s pushing empty space and galaxies apart, why isn’t it pushing the light faster?)
This guy puts a new spin on what we know and what’s in theory. Some of the stuff is antiquated and out of date. But he is very entertaining.
http://bigthink.com/experts/lawrencekrauss
I looked him up after hearing him on coast to coast. He’s written books on the physics of Star Trek which Wayne will love.
The second link you posted “CrashCourse #8” explaining how tides work by stretching the planet did not make sense.
In my comment at the top of the page, I used dark matter as example of an explanation for an unexplainable force created out of thin air. I never meant for dark matter to have any connection with the ocean tides.
Now I realize that there is no other explanation for why there is a tidal bulge exerting outward at high tide away from the effect of gravity. (Sarcasm?)
The theory given is that the earth is 13,000 kilometers across so that distance weakens the gravitational pull of the sun/moon on the far side of the planet. That would mean that the theoretical low tide effect on the far side of the planet would be slightly less than the high tide nearest the moon. Not that there will be a bulge in reality pushing away from gravity. In fact the man admitted it in his statement; “this is the weirdest thing about title bulges, you would think it would occur on one side of the planet facing the moon”… You can tell that he’s not buying the explanation either.
Then he talks of gravity being measured from the center of an object. (It is not, the center has no gravity. It is measured from the surface with all the bulk mass below you) he stretches the planet out as if that explained everything even though the bulge refused to go in the direction of this gravity example. He said the weakest effect is on each side of the planet experiencing low tide. I would think being halfway between would make no tide at all being in the balance between the two sides. But the water goes down as much as the tidal bulge goes up! Gravity? Dark matter? Higher barometric pressure? Something is squeezing the water around the middle like a water balloon.
Here is a animation of the tides high/low around the earth.
https://astronomy.stackexchange.com/questions/16769/what-is-the-real-position-of-the-tidal-bulge
It’s not what I had pictured in my brain but it does make sense that the tides would follow landmasses being higher in chokepoints and lower were water is deep with no tide at all in some places, 30 foot tides in Newfoundland and in Anchorage Alaska. I remember the cook inlet being so Muddy and filthy from the water rushing in and out. I was warned not to go out at low tide on the mud flat, it was pure quicksand.
Most earthquakes happen during low tide, there’s even a book written about it now.
Wayne:
Still working on your links, there is a lot to watch. Thank you for your humor, enthusiasm and your kindness. I’m not empathic enough to respond, but it does not go unnoticed.
I must disagree with Edward, he may be the center of the universe… But I orbit someone else and now must go.
Max-
Interesting stuff!!
Thanks for the Lawrence Krause link. I’ve seen a bit of his video appearances but truthfully, I find the guy to be an arrogant, blow-dried, publicity snark. (Tangentially, Dr. Leonard Susskind was having a cow a few months ago, he couldn’t sleep at night until he publicly condemned President Trump and everyone who voted for him.)
The tides explanation is a little different than I learned it, but I do not have the advantage of a blackboard to draw you diagrams, but I will make an attempt to paint a word-picture.
It may work better for you if you think of the center of the Earth as the point that is “affected” by the Sun (rather than the Moon), the point that is “falling” toward the Sun as it orbits the Sun, and the rest of the Earth is a stiff solid that follows that point around the Sun. It may also help if you think of an orbiting object as falling toward the Earth (or Sun) but that the surface curves away at the same rate that the object falls; thus the object never falls to the surface and remains in orbit.
In that case, the water that is closer to the Sun is trying to fall faster toward the Sun than the center of the Earth is (therefor faster than the surface of the Earth), thus is rises relative to the center of the Earth (therefor relative to the surface of the Earth), and the water on the far side of the Earth is not falling quite as fast as the center of the Earth is, thus it appears to rise relative to the center of the Earth (therefor relative to the surface of the Earth).
Tidal forces may be easier to understand if you imagine the Earth orbiting the Sun, where the Earth would definitely be “falling” in orbit, whereas the Earth does not orbit the Moon, so it seems strange to think of it as “falling” toward the Moon. However, the concept is still the same; the reduced pull from the Moon on the water on the far side still makes the water appear to “rise” relative to the center of the Earth.
“Something is squeezing the water around the middle like a water balloon.”
It is not a squeeze so much as the necessity for the water of high tide to come from somewhere, and since the equivalent of the center of the Earth (half way from the near side and the far side) is the only place it can come from, that is where it comes from. This is why ships like to sail when the tide is going out; they are helped along by the surface water that is flowing to other nearby locations in order to make up for the displacement of water as the high tide moves around the Earth.
I am sorry that the videos that I provided had technical errors. It is obviously a blue shift when a galaxy is moving toward us, so I suspect that the video tried to not confuse people with too many simultaneous concepts. It would have been better for them to have not mentioned that detail. They may have had similar reasons for making a simple shift in wavelengths in the other demonstration.
“Then he talks of gravity being measured from the center of an object.”
This is an assumption of gravity as a point source. It works well for calculations, especially for calculations far from the planet. For those working out orbits in low Earth Orbit, the shape of the Earth (e.g. mountains) comes into play, and there are well known and well understood adjustments to the equations for determining orbits around the Earth.
When you are at the surface of the Earth, 4,000 miles from the center, you experience 1G. When you are twice as far from the center, you experience 1/4G (gravity decreases with the inverse square of distance, G=1/(r^2), so it falls off pretty fast as you get out of low Earth orbit). For many calculations, it is easier to assume a point source of gravity and the reference gravitational pull being the amount at the surface of the planet.
The calculations change to a linear decrease in gravity once you enter the interior of the planet. That is because there is so much mass “above” you once you start your Journey to the Center of the Earth, per Jules Verne.
I hope this has clarified things. I am used to explaining things using paper or whiteboards, not words only.
Q: If an object is free falling in 1 G of gravity and it encounters something in its path as it falls, does the object continue to fall at the same rate?
Cotour-
depends on what you mean by “encounter.”
If it hits something, that would slow it down, but only temporarily. It’s always subjected to the gravitational force unless something else acts upon it.
Edward–
FYI–This guy has a 60 part series on “orbital dynamics.” Heavy on math but with animation & visuals, and they run 10-30 minutes each.
Jon Toellner
https://www.youtube.com/user/jondtoellner/videos
Orbital Dynamics Part 46
Gravitational Potential and Kinetic Energy
https://youtu.be/gkdhDAErtFc
(19:34)
So, Wayne, what you are saying is if an object / mass falls in 1 G of gravity from a known height we can know through measurement / calculation the time it will take to come to rest, assuming it does not encounter resistance from some other object that might oppose its falling.
Is that correct?
Cotour-
basically yes.
– Newtonian physics handles all common ordinary experience with moving objects.
You only need to appeal to quantum physics & relativity; at very small scales, when things travel close to the speed of light, and/or have large amounts of gravity in play, such as a black-hole or large star.)
If you drop a bowling ball from the top of the Empire State building, (disregard air-friction) it will fall toward the center of the Earth at a known speed & direction, until the sidewalk stops it. (at which time the energy of falling is converted into heat)
So, an object that is falling that encounters a static object in its way MUST slow down and in short order stop if that static object it encounters has the capacity to dissipate the energy represented by that falling object?
It’s all Newtonian physics. And that works with all ordinary human experience.
(You can navigate to the Moon fairly accurately with a slide-rule, a sextant, and a stop-watch.)
wayne,
Thanks for the video links. They seem to be based upon a different book than the text and reference books that I used in my class. Then again, my books were about a quarter century old when I took my class.
You are correct about the navigation to the Moon. That is how the Apollo astronauts did much of their navigation. Their onboard computer could also make the navigation calculations, and the people on the ground did their own calculations, too.
Meanwhile, I do not know what astronomers are going to do, now that their universal (intergalactic) distance markers (milestones?) have been shown to be unreliable. In addition, maybe we don’t know the age of the universe to the nearest 20 million years, after all.
Edward-
(-have some vintage slide-rules (ca. 1930’s) from my grandfather. amazing technology. I can sorta run a Theodolite, but if I have to use a sextant to navigate off earth, we will surely be Lost in Space.)
yes– I do find it amusing myself, that some stuff devolves into the whole ‘angels dancing on the head of a pin’ ‘thing. Along with “here be dragons,” and “insert mysterious X Matter, here.” Meanwhile, we can’t get a telescope up & running in Hawaii.
(It would not surprise me if we aren’t missing something very fundamental, but we just don’t get it, yet.)
I would however refer back to the “Stellar Distance Indicators” video I reference above; we can get out pretty far with a high degree of accuracy, as far as measuring distance, but all the Cosmology theories rely on large-scale distances for which we are less accurate.
tangentially– lengthy recent Joe Rogan Experience podcast (#1003) talking with physicist Sean Carroll. He’s not one of my favorites, but he’s interesting.
He slightly spills the beans on a recent LIGO detection that will be officially released soon. (possibly 2 neutron-stars colliding, but don’t quote me on that.)
Cotour:
“Two objects falling in 1G” like skydivers joining up to form a ring? Some must pull in their arms and legs to fall faster to join the rest by creating less drag. If some hit a hot air balloon and bounce off, it does not stop them from falling but it does slow them down. If they do not pop there parachute in time to increase drag, then momentum + mass is converted to heat.
If I remember equation, 32 ft./s squared squared… it is not consistent in air as the drag will prevent you from constant acceleration. Objects the fall too fast will burn up before they are able to slow down.
One interesting note, the dropping two different sized objects from the leaning Tower of Pisa and both of them struck the ground at the same time. I wonder how The law of gravity would have changed had one of the objects been a rare earth magnet which will drop slower because the magnetism reacts with the air causing a cushion and a slowing of the acceleration…
Edward:
I think I get it, the earth is falling towards the sun but the water nearest the sun is falling faster and causes a bulge. The water furthest from the sun is falling towards the sun a little slower and is causing a bulge.
Now I can ponder silly things like; if gravity travels at the speed of light and light cannot escape a black hole, how does gravity escape it?
I asked my brother about the tide thing, he says it simple. Water has a lot of weight, when the water piles up on the landmass under the moon, it pushes down so hard that it causes the middle of the earth to rise up so it looks like low tide as the water rushes out from the rising landmass.
I’ve been trying to find moons in tidal lock that are elongated from their near side falling faster than the far side. (our moon doesn’t count, it is missing 2 miles of its surface facing earth. A anti-bulge)
Io maybe? It doesn’t rotate but gets stretched between Jupiter and the other moons.
Max-
Interesting pondering.
[Gravity is a field which drops off in relation to distance, whereas photons are discrete units of energy.]
You would enjoy this: (well done and simple to understand)
“How Close Can You Orbit A Black Hole?”
Scott Manley
https://youtu.be/IM8HvoaKsBU
(7:59)
-at 1.5 times the Schwarzschild radius, photons in theory would orbit a black hole, [the “photon sphere”] and do so at the speed of light. In practice, it’s an unstable orbit, the slightest perturbation sends the photons into the black-hole.
“Stable circular orbits (of light) can only exist outside 3X’s the Schwarzschild radius.” (Which is referred to as “the innermost stable circular orbit.”)
and interestingly, if you were in that orbit, time would run about 30% slower.
Max wrote: “Now I can ponder silly things like; if gravity travels at the speed of light and light cannot escape a black hole, how does gravity escape it?”
The last that I heard, it is believed that the light photon, the particle, does escape the black hole, but that its wavelength is stretched so long, to infinity (or beyond), that it no longer has any “color,” or energy. Climbing out of the gravitational well drains the photon of all its energy.