Big bang questions

Factual Questions
1

I guess I’m ignoring the whole “space itself is expanding” thing. My first question: was there a point in time and space where you could have seen the expansion of matter rushing towards you? This postulates that gravity has slowed down the initial inflation so that it is no longer expanding at the speed of light. Plus, some particles would have to have condensed into forms that could even be seen to begin with.

Question two. If the first part is even possible what would happen to someone floating at the edge when the wave of expansion hit? Would clumps of matter (stars, I assume) go streaming past you with enough more or less empty space in between to survive or would it still be the surface of a sphere with countless trillions of particles dense enough that it would be like a cosmic shotgun blast that would shred you?

2

According to what I’ve read and heard, all of space is expanding at the same time so, no matter where you in space, it looks like everything is expanding away from you. For space to expand towards you, you would have to be outside of space, which makes no sense.

3

So, it is spacetime itself that is expanding, and it is doing so everywhere at a rate that is (presumably) the same for each observer proportional to distance to an observed distant reference; that is, the further away a reference point it, the rate of expansion of the intervening space is greater. (That ‘rate’ is actually measured in terms of speed per unit distance, i.e. km/s/Mpc because it increases with distance.) For various observational and theoretical reasons there is presumed to be an inflationary period near the very beginning that overcame the local gravitational energy of mass and thereafter slowed to the rate we see today, but at the extreme distance to the ‘edge’ of our observable universe (the comoving distance), that rate of expansion of spacetime was at just below the speed of light when the light was emitted, and exceeding it ‘now’ (in our reference frame) if we could somehow stand outside the universe and observe those distant points in simultaneously. The converse would be true for someone at what we observe to be the ‘edge’ of the universe; we would be seen moving away at just under the speed of light. At no time would the expansion of spacetime be contracting, but individual globs of matter would certainly be condensing into stars, galaxies, and larger scale cosmic structures.

Wherever you go, you will always appear to be at the center of your observable universe and can never be at a physical ‘edge’ of anything. What we are really at the edge of, at all times and regardless of where you are in space, is time; that is to say, the universe is really expanding into the time dimension and the ‘expansion of space’ is actually just a manifestation of time which we can observe because we are always stuck in the present moment of time. When you look out at the stars at night, you are actually looking ‘backwards’ in time because the light that strikes your retina was emitted years, decades, centuries, or many millennia ago for the visible stars and fluorescing nebulae in our galaxy, and even further back (tens of millions to billions of years) for light from other galaxies, although you generally need a telescope and false color processing to see that.

Stranger

4

Yeah, you can’t really ignore that.

5

Here’s a nifty timeline of the evolution of the universe.

Note that inflation lasted less than 10-32 seconds, even though the universe expanded 1026 times. The universe becomes transparent to light at about 300,000 years, which we now see as the CMB, the Cosmic Microwave Background. But stars as we know them don’t appear until about 150,000,000 years.

6

The universe is expanding faster than the speed of light.

Our observable universe has a “boundary” which is where the “edge” (note those quotes, there is not really an “edge” or “boundary”) is expanding faster than the speed of light. There is almost certainly more universe beyond that “edge” but it is moving away from us faster than we can ever see so, in a real sense, it kind of doesn’t exist for us. But, it is still there.

This does not violate the limit of the speed of light. Space is expanding…not moving.

ETA: I think our observable universe is about 46.5 billion light years in radius.

7

The discovery of the CMB was a real serendipity moment but fortune DOES favour the prepared mind.
What I find fascinating is you can “hear” the CMB between stations on older TVs and radios. How is that in any way shape or form deniable. :face_with_raised_eyebrow:

8

I don’t think anyone is denying it here. And it is cool that the “fuzz” on old CRT TVs was, in part, showing us the CMB.

9

We should be in awe of the ability of cosmologists to reconstruct such a timeline. Highly recommended for anyone even slightly interested in such things. Of course a lot of it is uncertain and subject to revision.

10

Science deniability is on the rise in way too many places. Not on here ( I hope ) but look at AGW …far more in the US beleive in the virgin birth. :zany_face:

11

This is where you’ve gone wrong. To be fair, it’s where most people go wrong.

A lot of people get the impression that the Big Bang was matter exploding out into an already existing empty space. That’s wrong. This is what also leads to your incorrect supposition that there is a place you could be where you could see the exploding matter coming towards you.

To really understand this, imagine that you have a flag that you put at some place in the universe. It’s a magic flag that never, ever moves from wherever you put it. It’s going to stay in that spot forever.

Now imagine that you have a second magic flag, that you place somewhere else in the universe. This flag also never, ever moves. Wherever you put it, that’s where it is, forever.

Now here’s the fun part. Even though neither one of those flags can move, they are both moving away from each other. They aren’t actually moving. The space between them is getting bigger. It doesn’t matter where you put those two magic flags. Wherever you put them, they keep getting further apart, even though neither flag is moving.

Now if you rewind that backwards in time, the flags get closer together. They all keep getting closer and closer and closer until finally they all squish together in a single point. That flag right next to you, it ends up squished in that single point. That other flag you plopped down on the other side of Alpha Centauri, that flag also gets squished down to the same point.

So where did the Big Bang originate? Right here. Where you are now. And way over there in that other galaxy. They were all the same point. There is no “outside”. All of the outsides are at that same point.

Admittedly it’s kinda trippy, but wrapping your head around that is the key to understanding what the Big Bang really was. It wasn’t just matter exploding out into a space that already existed. Space itself started from a single point and expanded outward.

Initially, all of the matter was squished together so tightly that the heat of it all being squished together prevented atoms from even forming. Eventually, everything cooled down enough that atoms could form, mostly hydrogen but some helium too, I believe. If you somehow existed at this time, you wouldn’t be able to “see” anything because there weren’t any stars or anything to produce light yet. And no carbon or other heavier elements to make a “you” out of either. Eventually the hydrogen and helium gas molecules clumped together and once those clumps got big enough, the pressure from all of the gas molecules being squished together (from gravity) caused fusion to start, and now you had stars. Now you finally had some light that you could see with.

Except you couldn’t exist yet to see anything, because the heavier elements that you are made out of didn’t exist yet.

Those early stars created the heavier elements through fusion, and when those stars got old and died, the bigger ones went all kablooey (how’s that for a technical term) and scattered their heavier elements all around out into the nearby universe. Those elements helped form newer stars and newer planets, and some of those planets (like Earth) ended up with lots of nice heavy elements to make interesting stuff out of. Like you. And now here you are.

12

Do you ascribe to the idea of branes?

13

As I understood it, Penzias and Wilson were assigned to find the source of noise that was interfering with the microwave transmissions that were part of the long distance network. Since they were close to Princeton (I drove that trip many times on the way to the nearby Holmdel Labs) they found someone who was planning to look for this very thing. Penzias’ obituary made it sound like they were doing cosmology work, but that’s not what I heard closer to the time. Penzias was quite capable of inflating his accomplishment. I’ve been in meetings with him and he was not my favorite Bell Labs person.

As for the more general case, to drag out an old analogy, think of a 2 dimensional being on an expanding balloon. At no place do you see the balloon expand into you, since that would require moving in the third dimension.

14

Yes I’m constantly surprised that people don’t appreciate or understand the value of verified predictions.
When I’ve seen YECs confronted about the CMB, they either quickly deflect to something else, or point to the “crisis in cosmology” or similar.

They don’t care that they don’t have an explanation for the CMB, or why god apparently gave our model “false” empirical support. As long as there’s something we don’t know yet, they can just reject the whole shebang.

15

Well, that’s impressive.

16

Nah, he funded a research project that I ran, so I gave a talk about it to him. Not a one-on-one.

17

I’m just going to throw in this random thought. If you think about the collapse of a massive star into a black hole and the formation of the singularity, basic thermodynamics says that as matter continues to collapse, it necessarily must start to become incredibly hot. As it continues to collapse into a singularity, “incredibly hot” must start to approach the state of the very early universe immediately after the Big Bang – where matter becomes dissociated into a quark-gluon plasma and the four fundamental forces may once again become re-unified. While “temperature” as we normally think of it is only applicable on a macroscopic scale, at the quantum scale it would still manifest in terms of extremely high energies of the quantum states.

Whatever the physical singularity at the center of a black hole may be, it has to be far more complex than just an “infinitely dense point”. The resemblance to the Big Bang in reverse is a really intriguing concept.

18

It might be a closer resemblance than you think. In cosmological models with a “Big Crunch”, where the universe reaches a maximum size and then contracts again, collapsing into a point, the Big Crunch singularity literally is a black hole singularity.

19

I was watching an old entry of a webcomic showing some hippie dude looking at the “snow” between the broadcast channels on an old tv.

When asked why is he looking at “nothing”, he replied that was the Cosmic Background Radiation…the “echo” of the Big Bang.

He was watching and listening to God create the Universe.

20

Note that, while the CMB is part of the white noise between the channels, it’s only a few percent.

Still, the Creation of the Universe is one heavenuva show.