observations and a question about space-time

[108 fountains]

This thread is more about cosmology than philosophy, but since the two are linked, I'm hoping this is the most appropriate forum and that there will be some readers who take an interest.

So my observations are these: The age of the universe is thought to be about 13.8 billion years old, and we can actually observe some quasars that are estimated to be nearly 13 billion years old and are the oldest and the most distant directly observable objects in the universe. It is well known that the universe is expanding and that the light we see from distant galaxies and quasars is coming from billions of years away. From this, it follows that the universe was much more compact and distances between objects were much smaller in the distant past. I think most cosmologists and physicists agree with these observations.

My question is this: If the early universe was much smaller in the distant past, why is it that the farther we look out into space, the farther we see in time? Put another way, if the universe is expanding, then at some point shouldn’t the farther distances in time become closer in space? I’ve tried to read a lot about cosmology, but I admit I am a real novice. I’ve never seen this question posed in this way in all my readings. Can anyone point me to a book or article that addresses this question?

[YesNo]

I don't understand the question, not that I would be able to reliably answer it. But I am interested.

I used to think in terms of "space-time", but I doubt that at the moment as well. It sort of leads to the idea of block universes and deterministic "eternalism" which I don't think is correct because it would void any free will we might have. Neither a single block universe nor a single present moment in the competing "presentist" view agree with relativity. A single present now would not agree with every frame of reference, so the single now idea is out. Also, a single coordiinate system for a block universe would not agree with every frame of reference, so the single block universe would have to go. Think of what a block universe would be for a photon. It would be a single point.

Anyway "I don't know" is the safest way to describe my authority level on this topic.

[kev67]

This thread is more about cosmology than philosophy, but since the two are linked, I'm hoping this is the most appropriate forum and that there will be some readers who take an interest.

So my observations are these: The age of the universe is thought to be about 13.8 billion years old, and we can actually observe some quasars that are estimated to be nearly 13 billion years old and are the oldest and the most distant directly observable objects in the universe. It is well known that the universe is expanding and that the light we see from distant galaxies and quasars is coming from billions of years away. From this, it follows that the universe was much more compact and distances between objects were much smaller in the distant past. I think most cosmologists and physicists agree with these observations.

My question is this: If the early universe was much smaller in the distant past, why is it that the farther we look out into space, the farther we see in time? Put another way, if the universe is expanding, then at some point shouldn’t the farther distances in time become closer in space? I’ve tried to read a lot about cosmology, but I admit I am a real novice. I’ve never seen this question posed in this way in all my readings. Can anyone point me to a book or article that addresses this question?

I think I understand what you mean. Do you mean that the spot right at the centre of the universe should be the oldest bit?

Anyway, the reason why the farther you look out into space, the farther you look back in time is because light travels at 186,000 miles a second. Our next nearest star, Alpha Centauri, is four light-years away, so we see it as it was four years ago. The light from some far-flung galaxy the other side of the universe might have taken milllions and millions of years to reach us.

I read a book recently that suggested The Big Bang theory might be wrong after all. For the universe to resemble what it does with the Big Bang Theory requires three phenomena: dark matter, dark energy, and rapid expansion during the early stages of the universe. No evidence for dark energy or dark matter has been found. There was great excitement when gravity waves were thought to have been discovered, because that would corroborate the rapid expansion assumed just after the Big Bang, but those gravity waves have not been verified by other teams yet, so far as I know. The reason it was thought that the universe was expanding was because of the red shift in light. However, most galaxies are thought to have giant black holes in the middle, which would also account for the red-shift. The giant black holes would also explain the shape of the galaxies' spiral arms without the need for dark matter or dark energy. If there was no Big Bang, then the universe might be much older than the 14 billion years we think it is now.

[YesNo]

Fraser Cain gave a summary of the "4 pillars of the big bang theory": (1) redshift, (2) nucleosynthesis, (3) cosmic microwave background radiation and (4) large scale structure of the universe. http://www.universetoday.com/106498/...-the-big-bang/

He also mentioned that we don't see objects older than 13.8 billion years.