Universe is 13.8 billion years old.... how can we see light from 13.5 billion years ago?

a reply to: DaRAGE

Cosmic inflation. The universe is expanding faster than the speed of light and this is both the cause and explanation.

No conservation laws are broken by space time expand caster than the speed of light.

The better question is, if the universe is 13.8 billion years old, and nothing can travel faster than light, why/how is the size of the universe estimated to be 92 billion light years across? The maximum possible size should be 27.6 billion light years across.

The better question is, if the universe is 13.8 billion years old, and nothing can travel faster than light, why/how is the size of the universe estimated to be 92 billion light years across? The maximum possible size should be 27.6 billion light years across.

Ok so this is usually explained in high school physics classes but I believe the answer is Red Shift and what we call the Doppler Effect.

Using radio waves we can detect the signature of light over time.



Hubble's Expanding Universe Red Shifts The Big Bang


What Is Redshift? | Astronomic

No problem.

The energy being produced in a condensed area was vast and the light waves we can see with our eyes and detect even with technology was overwhelmed by a source with light waves unknown to us, we can’t yet detect with either...
It’s there to see, we are simply blind to it...

originally posted by: FormOfTheLord
Ok so this is usually explained in high school physics classes but I believe the answer is Red Shift and what we call the Doppler Effect.

Sort of but not exactly. If a star is moving away from us through space, it will get red-shifted, due to the effect you mentioned, the Doppler effect.

When the cosmological redshift of other galaxies was first discovered, almost a century ago, astronomers thought what you said, that the redshift was due to the Doppler effect.

But we have since collected a lot more data which is much more accurate so that now we are certain the cosmological redshift is NOT due to the Doppler effect, which means the objects are not moving faster than light *through* space, rather the space between us and them is expanding, and that is how the most distant objects can appear to be receding from us at 3 times the speed of light. If the redshift was due to Doppler effect meaning they were moving though space then they would be limited to traveling no faster than the speed of light.

originally posted by: dalepmay
The better question is, if the universe is 13.8 billion years old, and nothing can travel faster than light, why/how is the size of the universe estimated to be 92 billion light years across? The maximum possible size should be 27.6 billion light years across.

That's an over-simplifed interpretation of general relativity, which doesn't prohibit objects billions of light years away from receding from us at three times the speed of light due to expanding space. Relativity only prohibits objects moving through space at faster than the speed of light and we don't see any objects doing that.

Begin by looking at a focal point, no matter what you’re at, only takes a few minutes.
Stay focused creating a form such as a square as your focal point. Now you are demonstrating how light operates, A basic fundamental of light is the fact light only and does see, only straight forward.

Each and every point of light seen in the sky is light traveling a straight line.

I’m sort of at another place right now on the topic junction like. That’s why the interest seems lacking. It isn’t though.

originally posted by: DEPAOR
Each and every point of light seen in the sky is light traveling a straight line.

Except when it's being bent by gravity.

www.youtube.com...

So just before the "big bang" the universe was mostly empty, except for a huge round lump of matter in the center?

way off, not even close. Space bends. Light doesn’t bend. Each stars seen light is traveling in a straight line but the source of the light isn’t from where the light is seen. In other words the star you look at could be behind you and isn’t where you are looking. It’s like a junction the light reaches, having identified, the light travels as the partical the light sees being it’s source.
Then when the light reaches the junction a change happens and space bends because the light now sees again and the source is different but there’s an exception, (getting to that later) here’s the thing though. None of the junctions are visible looking at the sky meaning each and every light source seen is a straight line.

The stars that show a glimmering affect is actually a type of junction between that straight line but didn’t bend.
Suppose you could say it’s like a disco out there. a reply to: wildespace

The pyramids are a decent example but aren’t why they were built. Take for instance you are light and you are standing beside a pyramid and see only the face side you are able to see. As light that is all you know meaning you think that triangular facial viewpoint is light and it’s source.
Then turning off the experimental hypothesis if you will and walk around the pyramid.
As light you aren’t going to think or say you changed or bent and it is much different though similar in terms of a pyramid and you ask so what happened.

I’m aware of exactly what happens at the moment light reaches the point of junction but I’m finding it quite difficult to decide on how to proceed while feeling eager to pick this thread apart like a hot duck.

Thank you this is the best explanation so farm.
But! how the hell can space get bigger,
further apart with out moving apart??

and IF we are a space bubble. does it have a out side?
can we see or find other bubbles?
I think scientists over complicate things.
like some kind of religion.
they may as well be on drugs.

originally posted by: Arbitrageur

originally posted by: FormOfTheLord
Ok so this is usually explained in high school physics classes but I believe the answer is Red Shift and what we call the Doppler Effect.

Sort of but not exactly. If a star is moving away from us through space, it will get red-shifted, due to the effect you mentioned, the Doppler effect.

When the cosmological redshift of other galaxies was first discovered, almost a century ago, astronomers thought what you said, that the redshift was due to the Doppler effect.

But we have since collected a lot more data which is much more accurate so that now we are certain the cosmological redshift is NOT due to the Doppler effect, which means the objects are not moving faster than light *through* space, rather the space between us and them is expanding, and that is how the most distant objects can appear to be receding from us at 3 times the speed of light. If the redshift was due to Doppler effect meaning they were moving though space then they would be limited to traveling no faster than the speed of light.

originally posted by: dalepmay
The better question is, if the universe is 13.8 billion years old, and nothing can travel faster than light, why/how is the size of the universe estimated to be 92 billion light years across? The maximum possible size should be 27.6 billion light years across.

That's an over-simplifed interpretation of general relativity, which doesn't prohibit objects billions of light years away from receding from us at three times the speed of light due to expanding space. Relativity only prohibits objects moving through space at faster than the speed of light and we don't see any objects doing that.

originally posted by: carewemust
So just before the "big bang" the universe was mostly empty, except for a huge round lump of matter in the center?

No, it was more like a thick soup of the most primal particles (probably quarks and electrons), and gradually those formed into atoms, while space itself was expanding very rapidly.

originally posted by: DEPAOR
way off, not even close. Space bends. Light doesn’t bend. Each stars seen light is traveling in a straight line but the source of the light isn’t from where the light is seen. In other words the star you look at could be behind you and isn’t where you are looking. It’s like a junction the light reaches, having identified, the light travels as the partical the light sees being it’s source.
Then when the light reaches the junction a change happens and space bends because the light now sees again and the source is different but there’s an exception, (getting to that later) here’s the thing though. None of the junctions are visible looking at the sky meaning each and every light source seen is a straight line.

The stars that show a glimmering affect is actually a type of junction between that straight line but didn’t bend.
Suppose you could say it’s like a disco out there. a reply to: wildespace

Sorry, hard to understand what you wrote here about junctions and sources, but it's a fairly established fact that light follows the curved space-time, resulting in gravitational lensing. We have many space photos that show that.

originally posted by: carewemust
So just before the "big bang" the universe was mostly empty, except for a huge round lump of matter in the center?

No. Just before the big bang, nothing else of our universe existed except for the singularity. That singularity was not in the "middle of" our universe because our universe did not yet exist. That singularity was what would eventually become our universe, including the space between the stuff.

The Big bang was NOT and explosion of "stuff" into our pre-existing empty universe. Instead it was the expansion and creation of our very universe itself -- the very fabric of our universe and the stuff.

That is to say, even the "empty" fabric of space in which all the stuff resides was created by the Big Bang as well, according to the theory.

originally posted by: Soylent Green Is People

originally posted by: carewemust
So just before the "big bang" the universe was mostly empty, except for a huge round lump of matter in the center?

No. Just before the big bang, nothing else of our universe existed except for the singularity. That singularity was not in the "middle of" our universe because our universe did not yet exist. That singularity was what would eventually become our universe, including the space between the stuff.

The Big bang was NOT and explosion of "stuff" into our pre-existing empty universe. Instead it was the expansion and creation of our very universe itself -- the very fabric of our universe and the stuff.

That is to say, even the "empty" fabric of space in which all the stuff resides was created by the Big Bang as well, according to the theory.

You might be going a little beyond what the big bang theory really covers according to Matt at PBS Spacetime. He says the big bang theory covers the universe going back to when it was very dense and very hot but then we start to run into problems with not having adequate theories to explain observation even before the hypothetical singularity which is far from certain since "singularity" can be interpreted as a code word for we don't really have a good description or understanding. Watch the last 1 minute if not the whole video:

What’s Wrong With the Big Bang Theory? | Space Time | PBS Digital Studios


So if we don't even understand it up to the singularity and don't think singularity is a very good description, then trying to speculate on what was before the big bang is something people like Lawrence Krauss might do, but I think he will also tell you it's speculative and not based on a sound theory like the Big Bang theory.

I think people love to speculate about "before the big bang" (if that even makes any sense if time started with the big bang) because so far it's probably impossible to prove them wrong. If they talk about what can actually be proven or measured, then it might be falsifiable. Matt in the video is open to the idea that theory might take us further someday, but I agree with him that the big bang theory as it stands today does not really explain the origin of the big bang.

a reply to: Arbitrageur


You're right. When I was writing my post, I was cognizant of the fact that the Big Bang theory does not current tell us what existed before the big bang, or what it was exactly that caused the bang, or even what banged. I was trying to simply a little too much by throwing out generalizations of what the Big Bang Theory said the state of existence was prior to the big bang, but looking back at my post I think those generalizations inaccurately depict what the theory says.

But still, in general, the idea is that our universe did not exist prior to the Big Bang. There was no place for the lump of "matter" (as carewemust called it) to be in the center of, and in fact the physical properties of our universe did not yet exist in order for that "limp" to be matter.

Like I said, the Big Bang was not an explosion of stuff into the space of our universe. It was instead the creation and expansion of that space itself.