How can radiation from the Big Bang come from all directions?

[phinds]

The CMB is a wall we can not see past it, and it is going away from us at light speed.
We estimate that the universe is 14,500 million years old because we can't see objects older tham that.
But we know that galaxies and stars needed more time to allow for what we actually see, and we invented inflation, an era that suposedly allowed everything to move faster than light, violating the GR rule that nothing can move faster than light.
We are violating the laws we have, a law that we can not see an exception anywhere in the visible universe.
What I am postulating is that instead of believing that during an inflationary era some parts or all the parts of the universe moved faster than light, the opaque era may be longer, but we can not see exactly when the universe started because of the CBM light wall that surround us.

You misunderstand metric expansion. Things receding from each other is not proper motion. Nothing ever moves, or has moved, faster than light.

 

[phinds]

Concerning that the CBM is part of the standard universe model need no more explanation, I think that we need to rethink every part of the standard model, because it is not explaining many data we are aquiring wirh the new isnstruments.
Accepting the standard models would condemn us to not accepting GR by not question the then standard model.
That is how science advance, by questioning everythin all the time, even when we have to start iver again and again

There is nothing wrong with the Standard Model, just with your understanding of it. If you think there are experiments that show a violation, please be very specific and say what they are.

 

[bapowell]

we invented inflation, an era that suposedly allowed everything to move faster than light, violating the GR rule that nothing can move faster than light.

This is false. Things did not move "faster than light" during inflation any more than they do during decelerated expansion. If this statement confuses you, do some reading about the metric expansion of space, or have a look here: https://www.physicsforums.com/insights/inflationary-misconceptions-basics-cosmological-horizons/. Before discarding an idea, I urge you to learn more about it.

 

[Rafael Munoz m]

Bapowell
Thank you, it certainly made things clear

 

[nikkkom]

Once atoms formed, light and matter stopped constantly interacting with one another, and photons were suddenly able to travel freely. As a result, the Universe became transparent.

One instant it was an opaque soup and the next one a transparent universe being filled with protons and neutrons.

That instant before it became transparent, we see as a surface emitting the background radiation or a surface of last scattering.

Wrong. Hot ionized hydrogen gas did not *instantly* became neutral. It happened gradually, over some 100 000 years.

We refer to this epoch as the "Surface of Last Scattering;" light from this period is observed today as the CMB or background radiation or short wave background radiation, because it is reaching us now as shortwave radiation from all around us.

Since we cannot be outside our universe, we are inside and it is like if we were inside a sphere with us at the center; the same for every place in the universe so every place is the center and we are just one of those places that feel at the center of the universe.

That background radiation surface we see today is that surface of last scattering

Sort of. I see it this way. At 400 000 years since BB, I'd still see nothing but a uniform red glow (~3000K) coming from everywhere. But at 500 000, I'd start noticing that it looks like I'm at a center of a transparent bubble, which has the opaque glowing red walls, approximately 100 000 light years away from me. Still almost the came color temperature.

This apparent "bubble" would grow with time. After a few millions of years, the grow would become noticeably redder, eventually shifting into infrared. It's not because "walls" are colder - it's because they are moving away - the gas in them is not stationary in respect to us, it's moving away. Doppler red shift.

The "walls" of this bubble are exactly the regions which were ~300000 years old and which experienced hydrogen recombination, emitting this red glow in the process. They are not paper-thin - they are about 100 000 light years thick.

By now, the walls are (apparently) 13.7 billion light-years away from us.

 

[bapowell]

By now, the walls are (apparently) 13.7 billion light-years away from us.

They are closer to 46 billion light years away.

 

[nikkkom]

They are closer to 46 billion light years away.

I meant that CMB light we detect today traveled 13.7 billion years. I don't want to get into the discussion of many more different ways to express the distance to the surface of last scattering.

 

[bapowell]

I meant that CMB light we detect today traveled 13.7 billion years. I don't want to get into the discussion of many more different ways to express the distance to the surface of last scattering.

That's fine. Just pointing out that what you wrote is incorrect, lest it lead to confusion. Because of the expansion, the distance traveled by CMB photons is longer than just time multiplied by the speed of light.

 

[Ophiolite]

Surely that point is covered by nikkom's paranthetic use of the word "apparently"? I actually found your clarification muddied the issue for me, since the use of "apparently" seems to make his statement correct. Now I don't understand why you would consider it wrong. In what way does the CMB not appear to be 13.7 billion years away?

 

[Jorrie]

In what way does the CMB not appear to be 13.7 billion years away?

As bapowell said, you cannot multiply light travel time by c and hope to get any cosmological distance that makes sense. Some popular writings try to call it "light travel distance", but even that's wrong. The 13.7 billion years is just light travel time and that's that.

When the light left the region of the observed CMB, it was only 42 million light years (proper distance) from the region where we find ourselves in. By now that distance has expanded to over 45 billion light years. Yes, there are various other ways to express cosmological distances, but none of them gives you 13.7 billion ly for the CMB.

 

[Ophiolite]

I appreciate your effort to help me understand. However, what you have said seems to align with my previous understanding. But - because he has included the words "apparently" - it also, to me, accords with what nikkom said. You and bapowell appear to be correcting something that nikkom has not actually said - but would have said if he had not included the word apparently.

That said, I do not wish to derail the thread any further with a discussion that revolves around my reading comprehension.

 

[bapowell]

I appreciate your effort to help me understand. However, what you have said seems to align with my previous understanding. But - because he has included the words "apparently" - it also, to me, accords with what nikkom said. You and bapowell appear to be correcting something that nikkom has not actually said - but would have said if he had not included the word apparently.

That said, I do not wish to derail the thread any further with a discussion that revolves around my reading comprehension.

Ophiolite, have a look at the section entitled "The edge of the observable universe" here: https://www.physicsforums.com/insights/inflationary-misconceptions-basics-cosmological-horizons/. In particular, Figure 5 illustrates why the expansion of the universe increases the travel distance of light as compared to a static universe.

 

[Ophiolite]

Ophiolite, have a look at the section entitled "The edge of the observable universe" here: https://www.physicsforums.com/insights/inflationary-misconceptions-basics-cosmological-horizons/. In particular, Figure 5 illustrates why the expansion of the universe increases the travel distance of light as compared to a static universe.

I really am reluctant to be taking this off-topic, however... I think I understand the article you have linked to. I believe it reflects the understanding I have had of the subject for three decades or so.

But, you are now causing me to thoroughly doubt any part of that understanding. Perhaps the answer to this question will bring the matter to a close. In what way do the most distant galaxies not appear to be 13 billion light years away? I understand they are much further than that; I think I understand why they are much further than that; I do not understand why you assert they do not appear to be some 13 billion light years away.

Thank you for your efforts.

 

[phinds]

I really am reluctant to be taking this off-topic, however... I think I understand the article you have linked to. I believe it reflects the understanding I have had of the subject for three decades or so.

But, you are now causing me to thoroughly doubt any part of that understanding. Perhaps the answer to this question will bring the matter to a close. In what way do the most distant galaxies not appear to be 13 billion light years away? I understand they are much further than that; I think I understand why they are much further than that; I do not understand why you assert they do not appear to be some 13 billion light years away.

Thank you for your efforts.

What do you mean by "appear". A light beam hits a detector. It appears as a microwave. In what way does that lead you to conclude that it originated 13billion years ago? More to the point, in what way does that lead you to conclude that it started out 13 billion light years away?

My point is that it doesn't appear as anything other than a microwave that could have been sent from down the block. To reach any conclusion about when and where it started out, you have to use knowledge of cosmology and do calculations.