In self defense, I am not a real math or science guy, so my knowledge is from books or Nova-like programs aimed at lay-people.
I seem to recall (either from a lecture or from a TV science program) a photograph of some faroff star formations, and the lecturer/announcer stating that we were looking at the remnants of the light of the Big Bang.
Now, I thought that everything, including us (our planet, solar system, galaxy) originated in that Big Bang.
And, I thought that it was fairly well accepted that no matter could travel at greater than the speed of light.
So, my question is this:
How did we get here before the light from the Big Bang?
My guess is that I either heard this incorrectly (although I don’t think so), or that this person was misspeaking.
But, if not: My first thought was if two objects travel along a line in opposite directions, each travelling at greater than half the speed of light, their relative speed to one another is greater than the speed of light. However, the Big Bang certainly implies that everything started at a focal point, so aren’t we still travelling less than the speed of light relative to that point?
As a side note here, I’m only part-way through Brian Greene’s The Elegant Universe, so if this comes up later in the book, unboxed spoilers are okay
When you look at something x-light years away, you are seeing it as it was x-years ago. So the Andromeda Galaxy (visible with the naked eye) is 2+million light years away and therefore what you are currently seeing is the galaxy as it was 2+million years ago.
If you look at something 10 billion light years away, you are seeing it as it was 10 billion years ago.
If the Universe is 14 billion years old and you look at something at 13+ billion light years away, you are seeing the early cruft of the Universe.
You can’t see such cruft near us since the we are only looking back a short time when looking at nearby stuff. E.g., the Sun is only 8 minutes older from our point of view. Hardly a far look back.
inflationary expansion theory, yes? Suggests that for something like a few millithousandths of a second, just a few millithousandths after the BB, things expanded at a tremendous rate. I don’t quite recall if it suggests that things actually moved faster than c though.
IANACosmologist, but my understanding is yes and no: space itself expanded much faster than c, so nothing in space went faster than c. Clear? Yeah, me niether.
Nope. The things in space are limited to the speed of light. Space itself suffers no such restriction. All those galaxies and quasars and stuff that we see 12+ billion light years of were precipitated out there by the expanding front of space time.
Also, to say that space “moves at a given speed” is a bit of a misnomer. No point in space moves at all, but the shape of the whole thing changes. The straight-line distance between two points can grow faster than the speed of light, but since no information is being exchanged it’s all good.
I think what you are talking about is the background microwave radiation which is the red-shifted residual radiant energy from the BB. At the instant of initiation of the BB everything in the universe was at the same place, if you can call a point in space-time a place. This point of radiant energy began to expanded . As things expanded the wavelength of the energy lengthened and it cooled. Eventually some of the energy condensed out as matter surrounded by radiant energy. Expansion continued and continues today and we are still surrounded by the residual radiant energy left after matter condensed out and it now shows up as an electro-magnetic microwave radiation.
David Simmons has it — dollars to donuts, the “light from the Big Bang” that was being discussed was the Cosmic Microwave Background, which was emitted 300,000 years after the Big Bang. Before that time the Universe was essentially a plasma — electrons and nuclei hadn’t joined up to form atoms — and, among other things, this meant that the Universe was essentially opaque to radiation. So the Universe actually had some non-zero size when that light was emitted, and the light we see now as the CMB is that which was emitted at just the right distance from us 300,000 years ago to be reaching us now.
Beyond that, there’s the more subtle question of whether it’s actually proper to say that everything “sprang from some focal point” in the Big Bang. (Feel free to ignore the following, as I fear I’ve made it rather unclear.) What General Relativity tells us is that if you could somehow turn time around and watch the history of the Universe thus far in reverse, you would see the Universe getting hotter and denser. At some point the electrons would get stripped from their nuclei by the increasing heat (i.e. the time-reverse of the process described above); as you kept watching, the nuclei themselves would get torn apart into protons and neutrons, and then the protons and neutrons would get torn apart into quarks, again by the increasing temperature. But (here’s the important part) GR tells us nothing about the moment of the Big Bang itself, since at that point the Universe was supposed to be “infinitely hot and infinitely dense”, and physical theories can’t deal with infinities (or at least not without some serious mathematical pyrotechnics, as in QFT, but that’s neither here nor there.) All GR can tell us is that if we pick some arbitrarily high density, we can find some time after the Big Bang when the Universe had that density.
It’s a subtle distinction, but it means that within the framework of GR we can make a virtue of necessity and view the Big Bang as taking place “everywhere at once”, since GR can’t tell us anything about the time (if said last time actually existed) when everything was “in one place.” Most physicists think that if we ever get a quantum theory of gravity it’ll help us understand & hopfully get rid of the aforementioned infinities; but all we have these days in that direction are a couple of theoretically interesting but so far experimentally unverifiable theories.
If this is true (if space itself expands faster than c), then that would go a long way to answering my question. My limited understanding about space itself is that it is analogous to a balloon, with everything having a position relative to one another and to the origin. As the balloon inflates, we are increasing our distance from objects in space even while “standing still”, simply through the expansion of space itself. Yes? No? Does this then imply that the limitation of c is only with respect to objects relative to one another?
Fair enough, using the word “point” was a misnomer. I suggest that we all agree that the size of space/time immediately prior to the Big Bang was 42
The key is that the Big Bang was everywhere. We didn’t go from the location of the Big Bang to where we are now, we just stayed put. So we’re in the location of the Big Bang. Meanwhile, that light came from somewhere very distant, and that very distant location was also the location of the Big Bang, since the Bang was everywhere.
maybe it is a reflex from something further from that focal point than Earth. The ligh expanded faster but it might be reflecting and coming back again… can this be?
No, no, don’t feel that way. Everything about the BB and most of cosmology is impossible for us (except for a few geniuses) to get our minds around. The singularity of what was there before the BB does not make any sense, as there was NO space, NO time, actually nothing. How can our brains grasp that concept of nothing? Everything we know started with the BB, and will end if, as is one possiblity, the universe will eventually contract back to that one point.
As a humourous aside, the name Big Bang was coined by an astronomer who did not believe in it, and used it as a term of derision. As it was not really a bang at all or an exposion as we know the term, some years ago the astronomy magazine Sky and Telscope decided to have a contest to come up with a better, or more descriptive term.
After thousands of entries, they reluctantly decided that there was no term any better, so gave up. They printed some samples of entries. My favorite was; Bertha D. Universe.
Sir Fred Hoyle, and he should have been more cautious. One of the originators of the BB was George Gamow who was a noted wag. He seldom missed a chance at humor and if the theory turned out to be successful, and so far it is, how better to turn the tables than to adopt the derisive term as the name?
Okay, either this is absolutely true or it is the best whoosh ever
So, continuing along the same line of thought: Given that space and time are inter-related, (and especially given your user name), can we also state that no time has elapsed since the Big Bang?
I had thought that this was now discounted and the Universe was continually expanding? I was a little disappointed to hear this; Asimov had once postulated two symmetrical Universes (he was big on symmetry and balance). He suggested that as one Universe contracted to a point it created another Universe through a Big Bang. Then when that eventually contracted, it would create another Big Bang. Ad infinitum, I guess…
I don’t think so. Although the time and space coordinates are interrelated they are not interchangeable. That is, it makes no difference what you call up or, sideways or to and fro. The space coordinates are all equivalent. However none of them is interchangeable with the time coordinate.
Maybe this works. Time increase with increase in entropy. Entropy increases. Therefore time increases.
