The age of the universe

LowQCab

Joined Nov 6, 2012
4,311
"" When people are free to pursue goals unfettered by presumed limitations on what they can accomplish, they just may manage some extraordinary feats through the combined application of native talent and hard work. ""

I couldn't agree more !!!
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joeyd999

Joined Jun 6, 2011
5,417
What do you mean by no edge
The extent of our universe exceeds the extent our "light cone" -- how far we can see in the past.

Anything beyond our light cone is permanently hidden from us. We will never, ever know what lies there (I say, "There be dragons!"). Within our light cone, everything is smooth and equal in all directions, no matter your vantage point.

Therefore, no edge.

Here's the fun part: as the universe expands, our light cone grows smaller. Objects that used to be in our sight are lost to us as their relative speed approaches c.

Edit: further, with the latest JWST images, it appears things don't change much -- if at all -- regardless how far you look in the past.
 
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MrAl

Joined Jun 17, 2014
11,731
Analogies only go so far.

There is no "edge". There's what you can see, and what you can't beyond that.
Hi,

The word "edge" is used there as an operative to describe a place where we see a transition of some type regardless how wide or long or smooth that transition is. It may not even be uniform or can even change as we change our viewing perspective.
If you are uncomfortable with this, you may replace the word "edge" with the word "horizon".
I say this in reference to the "edge" we think of in terms of the observable universe not in reference to the totality of the universe because we don't know if the properties there are gradual (as I pointed out already) or abrupt.
 

MrAl

Joined Jun 17, 2014
11,731
There is no "edge" in space indeed ... I would argue that Time is the only edge the Universe has, if one accepts Time as being Spacetime's fourth dimension.
Hi,

I don't think there is any consensus on that except in terms of the observable universe.
 

MrAl

Joined Jun 17, 2014
11,731
The extent of our universe exceeds the extent our "light cone" -- how far we can see in the past.

Anything beyond our light cone is permanently hidden from us. We will never, ever know what lies there (I say, "There be dragons!"). Within our light cone, everything is smooth and equal in all directions, no matter your vantage point.

Therefore, no edge.

Here's the fun part: as the universe expands, our light cone grows smaller. Objects that used to be in our sight are lost to us as their relative speed approaches c.
Hi,

That line of reasoning only applies to the observable universe, and even in that case it's still a transition region.
 

drjohsmith

Joined Dec 13, 2021
852
And my argument is that there is nothing but the observable universe.

It really could be dragons beyond that, but to us it would make no difference.
Im smirking, thinking of the old maps of the world with " there be dragons here" around the edges,

Thanks I needed the smile,
 

xox

Joined Sep 8, 2017
838
Or maybe...

Billions and billions of years ago, our galaxy "fell into" the event horizon of an incredibly large black hole. The fact that the universe is expanding at an accelerated rate could thus be explained as the direct effect of the black hole shrinking over time, emitting Hawking radiation along the way, also at an accelerated rate. (Which is to say that large black holes are cold and evaporate slowly, whereas small black holes are hot and evaporate more quickly.)

The Cosmic Microwave Background is probably the best piece of evidence to support such a conclusion. Why? Because it has the exact signature of a perfect black body. Ergo: a black hole!


Cmbr.svg.png
 

MrAl

Joined Jun 17, 2014
11,731
And my argument is that there is nothing but the observable universe.

It really could be dragons beyond that, but to us it would make no difference.
Hello again,

I believe that is limiting your thinking. For example, you can't even see THAT so I could say that there is nothing beyond the 1 to 10 mile visibility reported in your weather report today, but that would also be limited thinking. While you may not be able to see beyond that limit today, you know for sure that there is something beyond that, and tomorrow you may be able to see farther.

If it really did not make any difference what was beyond that, nobody would be thinking and experimenting with this for the last 20 or more years, yet they are, and they are thinking WAY beyond that limit. This makes it perfectly natural to talk about.
 

joeyd999

Joined Jun 6, 2011
5,417
Hello again,

I believe that is limiting your thinking. For example, you can't even see THAT so I could say that there is nothing beyond the 1 to 10 mile visibility reported in your weather report today, but that would also be limited thinking. While you may not be able to see beyond that limit today, you know for sure that there is something beyond that, and tomorrow you may be able to see farther.

If it really did not make any difference what was beyond that, nobody would be thinking and experimenting with this for the last 20 or more years, yet they are, and they are thinking WAY beyond that limit. This makes it perfectly natural to talk about.
Analogies only go so far. I can "see" beyond the 10 miles with a radio.

One can see billions of light years with an infrared telescope floating around at a Lagrange Point in space.

Anything beyond our light cone is simply unobservable -- and never will be, no matter the technology. You may theorize/fantasize all you want about whats beyond, but without the ability to observe and test -- a requirement for me to take you seriously -- that's all it is and will ever be: a theory or a fantasy.

Our universe literally ends where the photon frequency = DC (of course, you never really get there).
 
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Thread Starter

cmartinez

Joined Jan 17, 2007
8,290
I believe I could argue the same using just classical physics. Thus, "you never really get there".
Right ... I hadn't thought of the possibility (or impossibility, for that matter) of a "quiet photon" before ... a photon with an infinite wavelength.
 

Thread Starter

cmartinez

Joined Jan 17, 2007
8,290
And here's the counter argument:



... a recent study places the age of the oldest known globular star cluster uncomfortably close to the 13.8 billion-year ceiling. If the universe was anything like the age Gupta suggests, however, we’d expect to see clusters that were 20 billion years old at least, and nothing like that has been found.
 

MrAl

Joined Jun 17, 2014
11,731
Analogies only go so far. I can "see" beyond the 10 miles with a radio.

One can see billions of light years with an infrared telescope floating around at a Lagrange Point in space.

Anything beyond our light cone is simply unobservable -- and never will be, no matter the technology. You may theorize/fantasize all you want about whats beyond, but without the ability to observe and test -- a requirement for me to take you seriously -- that's all it is and will ever be: a theory or a fantasy.

Our universe literally ends where the photon frequency = DC (of course, you never really get there).
Hi,

Well then you disagree with a huge number of scientists around the world working on these problems. Just so you know.
You are taking it upon yourself to decide for everyone what is real and what is not real, and that's quite a chore. That's always your choice though and we see these debates about other things too.
The imagination is not very expensive so there should be no problem using it :)

Example:
Imagine that you are wrong. Wasn't too hard to do was it? :)

Just to be fair, I can imagine that I am wrong instead. I don't seem to be suffering over it :)

So you don't believe in the multiverse. That's fine, but other people do and have actually conducted experiments. In science it's not about believing it's about proving, but you have to believe in the possibilities first.
 
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