This is kind of an esoteric, theoretical physics question for those who like to ponder such things. I was contemplating the theory of general relativity the other day and it’s implications on time dialation due to gravity and a question occured to me… Hey, I’m quirky that way…
As we approach densities commensurate with those of the emerging universe, femto-femto seconds after the blessed event (big bang), it seems to me that the gravity of such a universe would essentially arrest time. To move further back in time, even closer to the exact instant of the big bang would seem to be impossible.
Or, asked another way: At the instant of the big bang, wouldn’t the universe be unable to expand because time would be essentially frozen due to the immense gravity? It seems like there would just be a singularity of infinte gravity, a universe-wannabe, suspended in time. (I know, time has no real meaning before the birth of the universe, but you get my point)
Am I missing something? Is it possible that the theory of the big bang is flawed… and/or the theory of general relativity is flawed… and/or (at the very least) the estimated age of 12-18 billion years for the universe is grossly under the mark?
I have a train of thought that might explain it, but I hesitate to mention it at this point because (1) I want to hear what the experts have to say without muddying the pond and (2) it might be even stupider than my initial question since it pits infinities against infinities…
I’m thinking that your paradox here stems from a reference frame confusion (looking at the situation from “inside” the universe vs. “outside”), but I have learned through hard experience not to even try explaining weird stuff like this here, because when I do, it comes out sounding like complete gibberish.
I do indeed think often on esoteric physics stuff (it is a flaw of mine.) Some obervations:
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The Big Bang Theory is (IMHO) almost definately seriously flawed. It is at the moment only a theory, with relatively scant evidence, but then again what does one expect for an event that MAYBE happened 12-20 Billion years ago. Everything physicists state about the beginning of the universe is PURE conjecture. Gen. Rel IS flawed...it does not work at the quantum level. Even at larger levels it is not a big improvement on Newtonian Classical Physics (which is usually still used by NASA for space travel). Once again GR relies heavily on math, but has little empirical backing. The time dialation thing you are discussing for instance...there is no evidence to suggest that time is anything other than what it appears to be...a fairly linear steady progression in one direction. Physicist have come up with a bunch of EQUATIONS to suggest that it might not be so (you probably have heard the, "if you travel at the speed of light" theory) but there is no empirical proof, and in fact the theory is logically flawed.
For instance by that theory, Mercury and the Earth (which travel at widely different speeds) should actually be in different time periods. Perhaps only by a few seconds, but nonetheless. So if you tried to land on Mercury would you want to land where you think it is...or where it WILL BE? Does that make sense. If you stop to consider this away from mathematics, from a purely observational empirical perspective we can see this is false...because Mercury simply is where it currently is.
The speed of light limit to speed may also be another barrier that proves to be false...again because we have no evidence to suggest many of the equations used in GR have any empirical validity (some of the ones which predict planetary motion do, but they again Ptolemy's mathematics for predicting planetary motion work pretty well too).
As far as time goes, physicists have essentially been attempting to reduce both it and space into mathematical constructs...and here I suspect they are excercising brilliant math but poor science. The empirical evidence suggests only that time is what it appears to be...linear, unstoppable, not touched by anyform of matter or energy.
From the GR perspective gravity also does not make sense, but that is a topic for another post.
This is not true. Scientists have observed that high energy particles moving near the speed of light both in nature and in the laboratory have an extended existence in accordance with Einstein’s time-dilation equations.
No. Incomplete, sure, esp if you’re looking for a TOE, full of paradoxes even, but consistent within the limits of the math used and first-rate in describing the world we see. Doesn’t ‘logically flawed’ suggest to you that the theory is saying both A and ~A? Where are the ‘logical’ flaws?
OK, avalongod, to address one point at a time here:
The Big Bang model, is, indeed, based on very little evidence. However, any alternative that has been proposed is based on even less evidence. Further, aside from direct divine creation, there is no other theory at this time which remains consistent with all observations (direct creation can never be ruled out, because all observations can then be explained as “God just wanted it to look that way”).
“General relativity… does not work at the quantum level”: How do you know this? The fact of the matter is, at the present time we do not knowwhat laws hold in quantum relativistic situations. It is quite possible that GR doesn’t hold then. From our current knowledge, it is equally possible that QM doesn’t hold in such situations, either.
How much of an improvement GR offers over Newtonian mechanics depends on the situation. If, for example, you try to describe a black hole classically, you will get completely different answers than if you use GR. As another example, the deflection of light by large masses is exactly twice what would be predicted by Newtonian mechanics, but matches Einstein’s predictions exactly.
What the heck do you mean, what time appears to be? It doesn’t immediately appear to be anything in particular, from all that I can tell. What color is it? How large? The only way to describe it meaningfully is mathematically, and the only mathematical descriptions which remain consistent are those based on relativity, both special and general.
No, I’ve never heard the “if you travel at the speed of light” theory, or at least, not a scientific theory. I’ve heard theories of things travelling very close to the speed of light, and even theories of things travelling faster, but in the context of relativity, it’s not meaningful to talk about massive objects travelling at the speed of light.
Yes, time flows at a slightly different rate on Mercury from what it does on Earth, but it’s not enough to worry about when planning landings. And even in Newtonian mechanics, it doesn’t really matter where it is right NOW, all that matters is where it will be when you land on it, at which point, you’ll be on Mercurian time.
Ptolomey’s equations worked reasonably well. Kepler’s and then Newton’s worked better. Einstein’s equations work better yet. Your point?
GR is the only perspective in which gravity does make sense. Newton’s reason for why things fall amounts to “just because”. Einstein’s theory actually gives a reason for it.
I don’t have any objection to a person being anti-science, and if you don’t know physics and don’t want to, that’s your problem. But that being the case, please don’t try to barge into a scientific discussion and tell us that we’re all wrong.
I admit I am not familiar with these studies. Nonetheless I am not sure (from your description) that I would find them convincing. I am a physics layman, but it sounds like you are saying: 1.) physics though HEPs would last say 1 sec (probably much shorter I know, but bear with me), 2.) they observe them (infer would be a better word than observe...the existence of these particles themselves is not a FACT per se but is inferred through other means) to last say 10 secs. All this really proves is that we have a poor understanding of HEPs in the first place. Keep in mind, also that HEPs ALWAYS move at the speed of light, as far as I know, thus there would be nothing to compare them too...how do you know they are in a different time function when they always go that speed. I might add there are numerous inconsistencies in the whole theory of the HEPs...the notion of such things were created to observe certain phenomenon then those same phenomenon were often used to confirm the existence of HEPs. This ultimately is circular logic. Also keep in mind, even if the above is true, this is only evidence that the particles are aging slower...that is different from saying they are in another "time zone" if you will. IF I eat my vegetables I will age slower too, but time is the same for me. If I smoke six packs of cigs a day, I age quicker...you get the point. My point is that physicists often interpret data selectively.
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~~~Doesn’t ‘logically flawed’ suggest to you that the theory is saying both A and ~A? Where are the ‘logical’ flaws?
Well that is one example of a logical flaw, though I am not sure it does not apply. My example of a logical flaw was that things, whatever their speed, exist in the present, and that time moves at the same rate...things can not exist in the present and in the future at the same point, which to me seems to be necessitated by GR (in my layman's understanding).
I am interested in learning more from those who are more familiar with GR...please don't be annoyed if I am skeptical...I will point out the logical flaws that I see as I hear the theories.
Regarding the study you mentioned, you got me wondering also if it might be subject to a “file drawer” type of problem? Let me illustrate:
Researcher A decides if time dialation exists, splitting an electron ought to cause a certain reactive film to turn blue (obviously I am simplifying). He splits the e-, no blue. Dang, he goes back the the drawing board, decides he was wrong, what really should have happened was that a glass of water should have heated up. Split the e-, no hot cup of water. Phooey, slap those last two experiments into the “file drawer” meaning they never get published…they are essentially disproving experiments that no one ever sees (because usually they can’t be published). Now Researcher A thinks the split atom ought to cause a measurable increase in radiation. Nope that doesn’t work either. Another one for the file drawer. 30 experiments later Researcher A decides the split atom ought to cause sound vibrations in the air…lo and behold we get sounds vibrations. Publish that puppy in Nature…as if that was what you expected all along of course! The trouble is, if you run enough experiments you will expect to find significant results eventually BY CHANCE ALONE. Meaning that the results prove nothing.
So I would be curious to see if such a study has been replicated. I would be interested in a link if you happen to have one?
I have been through this one recently, and have had some success in finding the explanation for the gravity question, with regard to the early moments of time. The force of gravity does not manifest in the first period of universal expansion. That force manifests at a later time, coincident with the creation of baryons. The first moments of time might be governed by the unified field, or perhaps not. Anyway, for the first three or four seconds of time, there is nothing but hot quark soup in the universe. No gravity. I am not sure if there are even photons.
A relatively new feature of cosmology is the “inflationary epoch” during the opening moments of existence. During that epoch, it seems that space itself increases in volume at faster than the speed of light. The matter in the universe gets left behind in clumps, strings, and sheets. Most of the universe ends up (volumetrically speaking, that is) as big voids. Everyone who has ever been willing to explain this to me has gotten real vague about scale during the inflationary epoch. Maybe centimeters. Maybe bigger. Maybe femto seconds, maybe longer.
Of course that still doesn’t answer my (and your) question about the force of gravity. Just what is the Schwartschild Radius of the mass of the entire universe? If the inflationary epoch expands things by less than fairly big number of light years, it seems to me that when the protons and neutrons finally enter the picture (which sources I have found seem to place between 10,000 and 100,000 years from the beginning at the latest) there just ain’t enough room in the universe for anything but a black hole.
High energy particles leave distinctive signatures when they interact with other particles. Physiscists can detect the existence of most particles unambiguously. The first confirmation of extended particle lifetimes when they are moving very fast relative to us was from detecting particles produced by cosmic rays high ion the atmosphere that wouldn’t ahve made it to the Earth’s surface if their lifetimes were not extended.
They do not. Particles with no rest mass, such as photons, always move at the sped of light. Particles with non-zero rest masses, such as electrons and protons and neutrons, never move at exactly the speed of light. By pumping energy intot hem, we can make them get arbitrarily close to the speed of light.
Maybe a more concrete example is in order. The Global Positioning System works. If GR was incorrect, and time did not “slow down” when something is moving relative to us and time did not “speed up” when gravitational “force” is lower, then GPS would not work as well as it does. GPS relies on very accurate clocks in the GPS satellites. These clocks are purposefully set to run slightly slow when the satellites are sitting on the surface of the Earth before launch. When the satellite is put into orbit, its clock will run slower because it is moving relative to us (Special Relativity) and will run faster because it is farther from the Earth and the gravitational force is smaller (General Relativity). The GR effect is larger than the SR effect so the satellite clock would run fast unless it was set on Earth to run slow to counteract this effect.
“For GPS satellites, GR predicts that the atomic clocks at GPS orbital altitudes will tick faster by about 45,900 ns/day because they are in a weaker gravitational field than atomic clocks on Earth’s surface. Special Relativity (SR) predicts that atomic clocks moving at GPS orbital speeds will tick slower by about 7,200 ns/day than stationary ground clocks. Rather than have clocks with such large rate differences, the satellite clocks are reset in rate before launch to compensate for these predicted effects. … we can state that the clock rate effect predicted by GR is confirmed to within no worse than ±200 / 45,900 or about 0.7%, and that predicted by SR is confirmed to within ±200 / 7,200 or about 3%. This is a very conservative estimate.”
Interesting stuff…again I suspect this only demonstrates that perhaps things age slower at higher speeds…a bit of a close distinction, but an important one. Again, the GP satelites maintain a continuous and predictable presense in the present time. Perhaps high speeds effect the performance of atomic clocks in some specific way…again I am not necessarily saying that this IS the case…I am merely suggesting that the evidence could be interpreted in other ways that actually require fewer assumptions.
I’m curious why avalongod & chronos feel that the Big Bang theory is based on “little” evidence. My impression is that there are several independent lines of evidence that support the theory (expansion of space, cosmic background radiation, abundance of elements, etc.)
avalongod - it’s incorrect to state that the Big Bang is “just a theory” (suggesting you can’t accept it)…a scientific “theory” has a different definition than the common use of the word.
I’m glad JonF brought up the GPS example of time dilation in action. Avalongod - it seems like you would need more assumptions to explain it without Relativity.
GR is not flawed because it does not describe quantum effects…GR is not meant to be applied to quantum effects in the first place. Just because a theory does not explain every aspect of the universe does not mean it is flawed.
Well, you appear to be missing the point … the speed of the GPS satellites relative to us is not particularly high, when compared to the speed of light; any relative velocity causes a change in how time appears to run. It just happens that the GPS requirements are so precise that we can (and have to) account for the effect. However, there’s another effect; gravity or acceleration also causes clocks to run slower, so the GPS clocks run faster than our clocks because they are higher in the Earth’s gravitational field, and this effect is the opposite sign from and larger in magnitude than the velocity effect. (When you actually sit down to do the calculations, you usually do not calculate the effects separately; it’s more convenient to just calculate the overall effect).
A lot of very clever people have tried very hard to explain this effect in some other way than General Relativity, and all have failed. Believe me, assuming that energy transitions in cesium atoms (the foundation of atomic clocks) are somehow affected by velocity and/or gravity would lead to a much more complex and unrealistic theory. And it wouldn’t explain many of the multitude of observations; GPS is just an easily comprehendable example.
It’s a fact that time runs slower, on any kind of clock or time measuring device or “biological clock” or in any meaningful concept of time, in any system that is moving relative to you. It’s a fact that time runs slower, on any kind of clock or time measuring device or “biological clock” or in any meaningful concept of time, in any system that is accelerating relative to you or in a stronger gravitational field than you. How one explains those facts may vary; the best explanation we have right now for those facts is General Relativity. It’s incomplete, but there’s no question that it is correct to very high precision. Any other viable theory is going to have to replicate the predictions of GR essentially exactly except in a few pathological cases where GR breaks down.
You seem to be stuck with a concept of a Universal Time which flows the same for all observers. It just ain’t so. GR and SR do not require things to exist in the present and the future at the same time, but they do require discarding the notion of Universal Time. Not only do those theories require that; the universe requires us to discard Universal Time. Observations have shown us that time does not flow the same for all observers; and, as I said before, GR is the simplest and most accurate theory we have now for explaining those facts.
"again I suspect this only demonstrates that perhaps things age slower at higher speeds…a bit of a close distinction, but an important "
Could you elaborate? I see no distinction whatsoever.
Sure, every scientist wants his paper in Nature or Cell rather than Eastern Oconee Review of Inexplicable Phenomena, so null hypotheses can be ignored by some guy lusting after sky-rocket results. After all, maybe his methodology sucked or his grad students were stoners. So shelve those data and move on.
But scientists are aware that science constantly progresses by null results. Michelson’s and Morley’s failure to find evidence of ether drift is a (excuse the expression) classical example. More recently, Perlmutter worked to evaluate the rate of expansion of the universe, expecting to find it was either steady or decellerating. But his best interpretation of his data was that the rate is in fact accelerating.
Re the “file-drawer effect”: If someone had actually come up with some experiment which scientifically and reliably refuted either theory of relativity, it would take all of about three seconds for that person to get his or her butt to the computer and start writing up the paper for submission to the most prestigious journal available-- Disproving relativity would make a person an instant celebrity, and send all manner of good things that way. On the other hand, if a person verifies relativity (espescially special relativity) yet again, the result is likely to be regarded as boring. That’s the experiment, if any, that gets tossed into the filing cabinet.
Phobos: I did say that it’s the most logical conclusion to be drawn from the evidence, and that it’s the only known scientific model which works. The fact of the matter is, though, that in studying the big bang, we’re a lot more limited in our observations than we are with most physical phenomena. We can’t simulate the process in the laboratory, for instance, and until LISA gets launched, we’re limited to what we can learn from photons. If I want to study, say, beta decay, I can get a bunch of radioactive atoms, study a great many beta decays, look at the trails in a cloud chamber, observe any photons that are emitted at any stage of the process, change various conditions of the experiment and see how that affects the rate, etc.: I can’t do that with the Universe. Some things are just harder to study than others.
On the subject of whether it’s really time itself that is affected: Special relativity does not, strictly speaking, say anything about time itself. What it does say, is that any conceivable means of measuring time (a pendulum, a person’s pulse, the oscillation of a particular molecule, etc) will be effected in the same way. The simplest way to explain this is that all of these “clocks” are measing the same thing, i.e., time, and that time is affected by speed.
When I read the OP, I started wondering why did the universe expand at all. Wouldn’t it have been inside the Schwarzschild radius in the beginning? Why didn’t the universe just stay a singularity?
Interesting note on that, DrMatrix: The density condition for a closed Universe (assuming no complications like the cosmological constant; I’m not sure how that would affect it) is exactly the same as the density of a black hole with radius equal to the “look-back” distance. What this would mean is that a closed Universe, in a sense, is a black hole, and we’re all living inside it. What this also means is that all world-lines end up at the same point eventually, that point being the “big crunch” singularity. In other words, we can’t see the singularity at the end of the tunnel 'cause we’re not there yet, but it’s still part of the Universe.
Of course, even without regard for such considerations, the question “why did the Universe start expanding?” still doesn’t really have a good answer, anyway.
I think I understand your answer. We cannot see the Big Crunch singularity for the same reason the singularity of a black hole cannot be seen (even from inside the event horizon) – it is always in the future, at least until you hit it; then time ends. But what is the “look back” distance?
Most of what avalon wrote was adequately addressed, however:
GR is the theory that finally made gravity make sense. Before GR we just knew that there was some force-like effect on bodies and we could predict how this force-like property was going to affect the objects, but we didn’t have a clue why that force-like property existed. Newton just shrugged that part of it off.
chronos:
I suspect that avalon was just ‘misremembering’ something that he read. I’ve seen a number of texts suggest that there is a conflict between QM and SR and they cite the EPR paradox and Bell’s quantun non locality as an example. Perhaps avalon had GR confused with SR.
Trisk:
Well, I have to admit that I did not consider a case where gravity did not or could not exist during the Planck era. I’m not sure if you were trying to make some argument about mass in your ‘quark soup’, but it seems reasonable to assume that there was a huge mass persent… in fact, all of the mass of the universe. Now did that mass warp space? That’s a different question - and a good one (more on that later).
The only problem with this hypothesis is that it shoots M theory in the foot. I’m not saying that’s “necessarily” a bad thing, but my understanding is that one of the things that makes M theory so attractive is that it unifies all of the forces all the way back to ‘time zero’. M theory ‘requires’ gravity to be present from the start.
DrMatrix:
Yes, I’ve pondered this question too. The only conclusion I can come up with is that a black hole singularity and the primal singularity are not the same thing… well, duh!? Not only are they not the same thing, they are in some ways opposites. In a black hole all of the light cones tip inward - hence nothing escapes the event horizon and we end up with a contraction phenomenon. In the primal singularity the light cones must have tipped outward so that we ended up with an expansion phenomenon. Therefore, though they are both types of singularities, they are not the same.
Chronos:
I disagree. Our universe is still holding to an inflationary model where a black hole is, by definition, deflationary. If and when the inflation halts and deflation begins toward the big crunch, then we’ll be living in a black hole.
Now to my ponderings… One of my trains of thought was that during the Planck era (and possibly for a short period after) our universe had more than 4 physical dimensions… Well, that’s what M theory suggests, anyway. The theory and math of GR is euclidian, but perhaps in non Euclidian, 11 dimensional space, the time dimension is distorted in other ways that we’ve yet to fathom? This is not too different to what I thought Triskadecamus might have been proposing. If we allow that the time dimension might be distorted, the spacial dimensions might be distorted as well. And what is gravity but a distortion of space. Perhaps the ‘crowding’ of the multitude of dimensions during the Planck era had a counteractive distortion of space, causing gravity to not be manifest…
One of the other thoughts I had was that the expansion (i.e. acceleration) is counteractive to the gravitational force of the concentrated mass. If the gravitational force is nearly infinite, but the acceleration is (somehow) infinite (or at least orders of magnitude larger than the escape velocity of the primal singularity) then the local acceleration/gravity of individual quarks might dominate. In other words, they would be living in a different frame of time than the core of the universe. That gets us back to the question of what causes this ‘infinite’ acceleration…
Feel free to pick on these lines of thought (as if you needed to be invited). I’m not overly attached to them… their just strawman - thought experiments.