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Einstein Said Nothing Can Move Faster Than Light?
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Einstein's theory states nothing can move faster than light. How did we get all the way out here with images from the beginning of time still arriving? It is also accepted that the big bang pushed everything out instantaneously. Surely, the big bang theory proves Einstein wrong.
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"Intuitively then, here we are far away from the "centre" and yet if we look back towards the origin we see light that is still heading towards us. Therefore, in my ignorance, it seems that we travelled here faster than the light."
The reason this intuitive understanding is wrong is, annoyingly, tricky to explain, at least at an intuitive level. The best I can come up with is to repeat the analogy of blowing up a balloon. Now for this analogy to work you have to imagine that the Universe exists only on the surface of the balloon. Anything inside it is not a part of that surface, anything that is not on the surface is not in the "universe".
So, with that picture in mind, imagine what an observer on the balloon will see. As the balloon grows, and grows, and grows, then things on the surface will appear to be moving away from each other. On the other hand, he'll be unable to find the "centre of expansion", because the centre is somewhere in the middle of the balloon, and not on the surface, and so not in the Universe, so he cannot find it explicitly without leaving his Universe behind.
We can do even more with this analogy too. Firstly, any light that was created when this balloon Universe began will be trapped on the surface and so will expand with our observer as the Universe grows, so there's no problem of moving faster than light away from the source of the light. The source is everywhere, in his world view: all light moves about on the surface, and so all light created at the beginning of the Universe will stay on the surface and stay visible.
Secondly, one can perhaps see that if you put two dots near each other on the surface of the balloon, and then blow it up very first, that a) the two dots will appear to move apart, but that b) this won't be as fast as the speed the balloon increased in size. This difference can be measured, if you want some numbers then if a balloon initially 10cm across grows by a metre in Radius in a second, then two points separated by one degree would have been initially separated as measured on the surface by about 2mm but are now separated by about 2cm. So, while the speed of expansion of the balloon was 1metre per second, the speed at which the two dots moved apart as measure on the surface is not quite 2 cm per second = 0.02 metres per second, so that it's a significantly slower rate of separation. On the other hand, two dots on either side of the balloon, as measured again on the surface, will have separated by an apparent speed of about 3.1 metres per second, which is obviously much faster than the rate at which the balloon was growing!
I don't think that anything changes much as the speed of expansion of this balloon grows to high values, either, so that even supposing the balloon expansion could only happen at the speed of light then it ought to be clear that two points either side of the balloon will appear to be moving away from each other at a speed many times faster than the speed of light. This also allows us to explain the whole "meta-universe" idea, that there is a huge amount of the real Universe we cannot see. We can't see because in some sense it was on the "other side" of the expansion.
The whole point of the balloon analogy is to try to emphasise that all of the physics the guy living on the surface of the balloon does, must be done on the surface of the balloon. That, for him, is the Universe.
I hope very much that this analogy is helpful and accurate, although if you have any more questions then feel free to ask, or to read some of mibn's links.
The reason this intuitive understanding is wrong is, annoyingly, tricky to explain, at least at an intuitive level. The best I can come up with is to repeat the analogy of blowing up a balloon. Now for this analogy to work you have to imagine that the Universe exists only on the surface of the balloon. Anything inside it is not a part of that surface, anything that is not on the surface is not in the "universe".
So, with that picture in mind, imagine what an observer on the balloon will see. As the balloon grows, and grows, and grows, then things on the surface will appear to be moving away from each other. On the other hand, he'll be unable to find the "centre of expansion", because the centre is somewhere in the middle of the balloon, and not on the surface, and so not in the Universe, so he cannot find it explicitly without leaving his Universe behind.
We can do even more with this analogy too. Firstly, any light that was created when this balloon Universe began will be trapped on the surface and so will expand with our observer as the Universe grows, so there's no problem of moving faster than light away from the source of the light. The source is everywhere, in his world view: all light moves about on the surface, and so all light created at the beginning of the Universe will stay on the surface and stay visible.
Secondly, one can perhaps see that if you put two dots near each other on the surface of the balloon, and then blow it up very first, that a) the two dots will appear to move apart, but that b) this won't be as fast as the speed the balloon increased in size. This difference can be measured, if you want some numbers then if a balloon initially 10cm across grows by a metre in Radius in a second, then two points separated by one degree would have been initially separated as measured on the surface by about 2mm but are now separated by about 2cm. So, while the speed of expansion of the balloon was 1metre per second, the speed at which the two dots moved apart as measure on the surface is not quite 2 cm per second = 0.02 metres per second, so that it's a significantly slower rate of separation. On the other hand, two dots on either side of the balloon, as measured again on the surface, will have separated by an apparent speed of about 3.1 metres per second, which is obviously much faster than the rate at which the balloon was growing!
I don't think that anything changes much as the speed of expansion of this balloon grows to high values, either, so that even supposing the balloon expansion could only happen at the speed of light then it ought to be clear that two points either side of the balloon will appear to be moving away from each other at a speed many times faster than the speed of light. This also allows us to explain the whole "meta-universe" idea, that there is a huge amount of the real Universe we cannot see. We can't see because in some sense it was on the "other side" of the expansion.
The whole point of the balloon analogy is to try to emphasise that all of the physics the guy living on the surface of the balloon does, must be done on the surface of the balloon. That, for him, is the Universe.
I hope very much that this analogy is helpful and accurate, although if you have any more questions then feel free to ask, or to read some of mibn's links.
I think that how we can see the cosmic background radiation all around us and believe in a single origin for our universe from a finite point in spacetime, given that nothing possessed of mass could possibly outrun these photons of the CBR travelling at the speed of light such that they are in the path of our detectors today, when they must surely have passed through the space we now occupy long since, is a legitimate question that is barely appeased by inflationary theories and NEVER referred to by popular scientists.
It makes more sense to me to believe that the CBR actually comes from outside our universe and could be a confluence of signals from other 'big bang' events that created other universes before our own, originating from all directions in space time.
It makes more sense to me to believe that the CBR actually comes from outside our universe and could be a confluence of signals from other 'big bang' events that created other universes before our own, originating from all directions in space time.
Our universe did not emerge from some point in space and time. Our universe emerged with the unfolding of space time and had already been here about 377000 years prior to recombination and decoupling which liberated the CMB then and now evenly distributed throughout when the universe was about 1/1000th its current size.
It is easy to imaging the CMB as an enveloping sphere that exists at some 13.7gly distance. The fact is the CMB permeates the universe at all distances and in every direction. What we see of the CMBR is simply those photons that happen to be arriving at this destination in this moment in time.
It is easy to imaging the CMB as an enveloping sphere that exists at some 13.7gly distance. The fact is the CMB permeates the universe at all distances and in every direction. What we see of the CMBR is simply those photons that happen to be arriving at this destination in this moment in time.
I hoped that I'd addressed that question above, Colm. It certainly is a legitimate one... it does have an answer, that's difficult to grasp, which is that the Big Bang happened everywhere in the Universe. It happened next to me, next to you, outside the sun, at the centre of the Galaxy, over in nearby Andromeda... everywhere. So the photons in the CMB were all over the place, everywhere in the Universe, expanding with it. as Mibn points out, we are seeing the ones arriving here now -- but someone looking at the CMB in several hundred years' time would see essentially the same pattern, and someone looking at it now, but in a nearby galaxy, would see the same pattern too. It is not travelling from the beginning of time... it's travelling from everywhere.
I think as the two fellows above say, that you have grasped the wrong end of the stick, Col. Nothing can have passed through space in the past that didn't exist in the past. It's being created, much of it far away from where the "stuff" you suspect of passing through, will be.
That said, I do have a related thing I puzzle over occasionally. Ignoring the difference between a singularity and the very small, if physics insist the maths break down and singularities don't exist. We hear of a surprise as to why the background radiation is so similar no matter where we look in the universe, and state a theory such as inflation was needed to explain it. But if the universe was a single point at the start of time then it is all the same point and one would expect it to look the same everywhere as things expand. Granted symmetry breaks and things clump over time, as space is created, but why the surprise at the fact it all looks much the same everywhere ? The surprise would be if it was a striped or tartan pattern.
That said, I do have a related thing I puzzle over occasionally. Ignoring the difference between a singularity and the very small, if physics insist the maths break down and singularities don't exist. We hear of a surprise as to why the background radiation is so similar no matter where we look in the universe, and state a theory such as inflation was needed to explain it. But if the universe was a single point at the start of time then it is all the same point and one would expect it to look the same everywhere as things expand. Granted symmetry breaks and things clump over time, as space is created, but why the surprise at the fact it all looks much the same everywhere ? The surprise would be if it was a striped or tartan pattern.
Yes, it is -- I think I remember the relevant issue now!
The source of my confusion was that I was thinking about answering the question in the context of what comes after inflation, rather than what comes before. Although strictly speaking we don't actually know what comes before, the assumption always is that when the Universe was beginning its behaviour
was governed by a Quantum Theory of Gravity, and in addition that The Universe was so energetic that even the forces we see today (Electromagnetism, and the Weak and Strong Forces) were bound together. This small-scale, high-energy Quantum behaviour of an Early Universe might be expected to lead to "ripples" and general differences in behaviour depending on where things were going on. The nature of Quatum stuff is very random, so something happening in one place would not necessarily happen elsewhere, and the result would be that, gradually, differences would develop across spacetime, and these differences would get more and more pronounced. Therefore, in a model where the Universe increased in size slowly, you would expect huge variations across the Universe rather than a general isotropy (unless the Quantum Theory involved were somehow tuned to avoid these fluctuations being too significant, but most physicists hate fine-tuning (if anyone wants to comment on this or ask why, it really deserves a separate thread all of its own)).
The point of Inflation is that it blows the Universe up to a very large scale before these Quantum fluctuations in the shape of the Universe get too significant. Also, the fluctuations themselves get "locked in" to the shape of the Universe, so that it becomes both (a) mostly the same everywhere, and (b) not quite the same everywhere after all. These small ripples, not suddenly huge, become the spawning ground for galaxies etc.
The surprise of a Universe that is the same anywhere appears to be a surprise only in the context of trying to find a theory that explains it properly. Naturally a Universe that is mostly empty ought to look the same everywhere... but if it also had a beginning, and if at the beginning it was small, then various problems arise in trying to match what happened then to what is happening "now". These problems are best resolved using Inflation, which gives the early Universe too little time to evolve too far away from being Isotropic.
I think another thing that Inflation does is allow easily for the fact that regions of space that we are seeing for the first time still have the same CMB spectrum as everywhere else. If we are seeing them for the first time now, then in the past there was no communication between the two, and so no way for the newly-seen region to "know" how it was supposed to look to match with us. Inflation can explain this, too, by saying that the primary cause of the way things look in the CMB was determined very early on in history, and then essentially frozen into the Universe at all points, for all of the rest of Time.
Hope this helps.
The source of my confusion was that I was thinking about answering the question in the context of what comes after inflation, rather than what comes before. Although strictly speaking we don't actually know what comes before, the assumption always is that when the Universe was beginning its behaviour
was governed by a Quantum Theory of Gravity, and in addition that The Universe was so energetic that even the forces we see today (Electromagnetism, and the Weak and Strong Forces) were bound together. This small-scale, high-energy Quantum behaviour of an Early Universe might be expected to lead to "ripples" and general differences in behaviour depending on where things were going on. The nature of Quatum stuff is very random, so something happening in one place would not necessarily happen elsewhere, and the result would be that, gradually, differences would develop across spacetime, and these differences would get more and more pronounced. Therefore, in a model where the Universe increased in size slowly, you would expect huge variations across the Universe rather than a general isotropy (unless the Quantum Theory involved were somehow tuned to avoid these fluctuations being too significant, but most physicists hate fine-tuning (if anyone wants to comment on this or ask why, it really deserves a separate thread all of its own)).
The point of Inflation is that it blows the Universe up to a very large scale before these Quantum fluctuations in the shape of the Universe get too significant. Also, the fluctuations themselves get "locked in" to the shape of the Universe, so that it becomes both (a) mostly the same everywhere, and (b) not quite the same everywhere after all. These small ripples, not suddenly huge, become the spawning ground for galaxies etc.
The surprise of a Universe that is the same anywhere appears to be a surprise only in the context of trying to find a theory that explains it properly. Naturally a Universe that is mostly empty ought to look the same everywhere... but if it also had a beginning, and if at the beginning it was small, then various problems arise in trying to match what happened then to what is happening "now". These problems are best resolved using Inflation, which gives the early Universe too little time to evolve too far away from being Isotropic.
I think another thing that Inflation does is allow easily for the fact that regions of space that we are seeing for the first time still have the same CMB spectrum as everywhere else. If we are seeing them for the first time now, then in the past there was no communication between the two, and so no way for the newly-seen region to "know" how it was supposed to look to match with us. Inflation can explain this, too, by saying that the primary cause of the way things look in the CMB was determined very early on in history, and then essentially frozen into the Universe at all points, for all of the rest of Time.
Hope this helps.
Yes indeed, that does help. Quantum fluctuations, I think that what I'd like to exclaim too coming to grips with this sort of thing.
Although interestingly your last paragraph sort of raises the same question again. No communication between the two seems odd if at the start of time they were the same point. But I'll put that down to fluctuations too then.
Although interestingly your last paragraph sort of raises the same question again. No communication between the two seems odd if at the start of time they were the same point. But I'll put that down to fluctuations too then.
I don't really understand that point myself. I think the point is that two places that were initially close together, then very quickly out of touch again, for essentially the rest of the history of the Universe, and are only now coming back into contact with each other... that's a lot of time for things to have changed beyond recognition. And yet that's not what is seen. Instead, everything seems to match up almost exactly. If you had a twin brother and you were separated at birth, you would be amazed if 70 years later your lives had taken the same course and there was essentially nothing at all to tell you apart. Even identical twins who live with each other for their entire childhood years usually diverge slightly.
May I just point out that my suggestion that the CBR comes from outside our universe does nor require any new theories such as cosmic inflation to be invoked. Remember Occam's razor?
The fact that this ubiquitous bathing of our universe by the CBR has been altered such that it leaves the signature of the birth of our universe, if anything, adds credibility to my proposed CBR origin, and c is still c!
The fact that this ubiquitous bathing of our universe by the CBR has been altered such that it leaves the signature of the birth of our universe, if anything, adds credibility to my proposed CBR origin, and c is still c!
Albert did not state that nothing moves faster than light. He merely said light is constant! Energy E = Matter in a constant squared (this constant is light)
His Theory says nothing about (objects already moving at C or multiples of C)
He merely states that on earth(which is a vaccuum) nothing can move faster than the speed of light!
His Theory says nothing about (objects already moving at C or multiples of C)
He merely states that on earth(which is a vaccuum) nothing can move faster than the speed of light!
-- answer removed --
Thought is not faster than the speed of light . But within the confines of our cranium it is effectively instantaneous. And yes Einstein is right 'nothing' can travel effortlessly faster than the speed of light. But for everything that is not 'nothing' but 'something' such as the photons of the CBR, the light barrier can be shown by a huge massive bank vault-full of incontrovertible data to be insurmountable, and cosmic inflation nothing but science fiction parading as science fact.
Is it so hard to accept that light from other universes can spill into our own?
Is it so hard to accept that light from other universes can spill into our own?
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