A really big question

[BeyondKnowledge]

And there can never really be enouth time.

Because of the accelerating expansion.

The implication being that some regions are receding away from us so fast that their light can never reach us.

No matter how long we wait...

Did you read my post before the one you quoted? I am not entirely convinced the universe expansion is accelerating.

It is moving faster the farther back in time the measurement is taken. That means it is slowing down.

[Randyvine]

Alright gentlemen, I'm dying to know if this just got missed or was it not worth
answering maybe it doesn't make much sense IDK. I can take it if it's an eye roll
honestly.:)

 Something seems way off to me concerning speed of light and the
distance of any given celestial object we know is there because of it's light.

Or maybe we can't be sure the planet or star we see in the night sky is still there.
 I mean if a star is say fourteen light years away form planet Earth. How do we know
that star is still there when the light telling it IS there, is delivering fourteen year old
information?

How does this work?

[BeyondKnowledge]

Alright gentlemen, I'm dying to know if this just got missed or was it not worth
answering maybe it doesn't make much sense IDK. I can take it if it's an eye roll
honestly.:)

 Something seems way off to me concerning speed of light and the
distance of any given celestial object we know is there because of it's light.

Or maybe we can't be sure the planet or star we see in the night sky is still there.
 I mean if a star is say fourteen light years away form planet Earth. How do we know
that star is still there when the light telling it IS there, is delivering fourteen year old
information?

How does this work?

Well, the light from something 14 light years away takes 14 years to get here to be seen. The same for something a billion light years away. We are seeing it as it was a billion years ago.

Light travels at aconstant speed. A light year is the distance light travels in a year. 

So not even the Moon is where we see it when we look at it. It is about 1.5 seconds farther along in its orbit than where we see it.  That is not much but it is there. We don't see anything in space where it is now, just where it was and how it was.

As far as knowing what happened before we see it happens with objects that far away, no one knows until we see it happen. Certain actions can be predicted based on past observations. Such as a star showing signs of going nova soon. But we only see it happen long after it has actually exploded. 
 
I hope that helped.

[chr0naut]

Yes, indeed. Now consider this paradox.

The cosmic boundary is, as you say, expanding faster than light. But the cosmic boundary is in fact light – what else could it be? In the (imaginary) frame of reference of an object at the cosmic boundary, the wavefront of expansion would still be travelling at the speed of light, because nothing in the universe can go any faster.

But no such frame of reference can be postulated. Every spot in the cosmos is actually its centre. This is the reason why some physicists (Stephen Hawking was one) like to say the Universe is finite but boundaryless. If the cosmos is boundaryless, there is nothing to stop anything extending beyond it. But that extension merely expands the Universe, so the answer to ‘what’s outside the Universe’ effectively becomes ‘the Universe’.

The calculated spatial expansion of the Universe is, as you say, surperluminal, but to a photon, ‘escaping the Universe’ and ‘expanding the Universe’ are one and the same thing. This is the point I want to make.
 

*     *     *

This is a very Christian metaphor, but of course you know that. Only the Peoples of the Book regard the world and humanity as broken and in need of repair. The cosmos might be riddled with misery, death and disease in other traditions, but it’s still exactly as it was meant to be. To quote the Tangerine Antichrist, ‘it is what it is.’
 
Ah, but how long exactly is that metre, again? Depends on how fast it’s going, doesn’t it?

A meter is defined as the distance that light travels in a vacuum in 1/299792458⁠th of a second. As 'c' is invariant within all reference frames, so is the meter derived from it.
 

Oh yes. Surely you don’t think we should ask physicists about ontology?

Surely physicists are 'natural philosophers' by another name?

And it’s no bloody use asking a theologian about anything...

Because they can offer nothing new, or because you don't agree?

[andy06shake]

Did you read my post before the one you quoted? I am not entirely convinced the universe expansion is accelerating.

It is moving faster the farther back in time the measurement is taken. That means it is slowing down.

I don't think we can entirely be convinced of anything. 

Science does not claim certainty...

As you know theories are always provisional.

But according to the standard cosmological model.

Or at least my understanding, which, granted, is somewhat tenuous at best.

The expansion of space is currently accelerating.

[BeyondKnowledge]

I don't think we can entirely be convinced of anything. 

Science does not claim certainty...

As you know theories are always provisional.

But according to the standard cosmological model.

Or at least my understanding, which, granted, is somewhat tenuous at best.

The expansion of space is currently accelerating.

Yes, a good scientist is certain that nothing is truly certain. There is always more to learn.

I am thinking of contacting the local college physics department about some of these questions. I did not even know they now have an observatory with a 24 inch telescope until yesturday when I was looking into that.

[Randyvine]

Well, the light from something 14 light years away takes 14 years to get here to be seen. The same for something a billion light years away. We are seeing it as it was a billion years ago.

Light travels at aconstant speed. A light year is the distance light travels in a year. 

So not even the Moon is where we see it when we look at it. It is about 1.5 seconds farther along in its orbit than where we see it.  That is not much but it is there. We don't see anything in space where it is now, just where it was and how it was.

As far as knowing what happened before we see it happens with objects that far away, no one knows until we see it happen. Certain actions can be predicted based on past observations. Such as a star showing signs of going nova soon. But we only see it happen long after it has actually exploded. 
 
I hope that helped.

I had a response for you and then everything went to #### again and
I found myself revisiting the two year desolation from hence forth I came.
To much drama trauma right now to remember but it's pretty much what
I thought with your better explanation. Yes that helps, I have to go lay down
now.

[BeyondKnowledge]

Well now, I stumbled across this while at a restaurant today. Einstein has a theory that gravity changes the speed of light and it recently seems to have been proven experimentaly.

Now to apply this to the ongoing discussion. 

As the universe spreads out, gravity gets weaker with distance. This is proven on a smaller scale by orbital dynamics. Now as gravity weakens, light slows down. 

How does this effect our deep space opject observations? 

https://www.zmescience.com/science/physi...ed-gravity

Or perhaps the gravity variation in the elevator position just changed the time reading as it is known that objects in orbit experience time differently than on the surface of the Earth. Time runs faster with less gravity. 

It is getting all timey wimey again isn't it.

Where is my Tylenol as I am not allowed to have aspirin according to my doctors. Perhaps I need to avoid using my phone at restaurants as it may be showing the effects of bistro math.

[Astyanax]

A meter is defined as the distance that light travels in a vacuum in 1/299792458⁠th of a second. As 'c' is invariant within all reference frames, so is the meter derived from it.

Sure. But my metre is still longer than the fast guy's metre.

How far does a photon travel between (1) the forepart of a large relativistically moving object and your detector compared with (2) a photon from the rear end of the same object, and what does that tell us about the above definintion? I remember our lecturer trying to explain Terrell rotation to our class; it was a bit counterintuitive to say the least. It should comfort both of us to know this is a subject that tied some of the best minds of humanity into knots for more than fifty years; Lorentz himself never properly grasped it.
 

Surely physicists are 'natural philosophers' by another name?

Nietzsche called philosophy the gay science, remember? Better not tell our MAGA friends or they’ll be lynching philosophers along with scientists.
 

[No use asking a theologian] because they can offer nothing new, or because you don't agree?

Because they are professional truth-fudgers and double-talkers. They can’t help it, poor fellows. Theology is an attempt at the intellectual study of something that is acknowledged to be rationally incomprehensible, so it would be foolish to expect either logical rigour or fidelity to empirical evidence from a theologian.

In their different ways, philosophers and scientists each make honest efforts to discover the truth and explain it; theologians try to make reality conform to a predetermined set of beliefs.

[BeyondKnowledge]

In their different ways, philosophers and scientists each make honest efforts to discover the truth and explain it; theologians try to make reality conform to a predetermined set of beliefs.

I really like that a lot.