by Ann » Mon Jun 20, 2016 4:41 am
Chris Peterson wrote:geckzilla wrote:If spacetime defines age, then how does it, itself have an age?
I don't think it does. Spacetime defines the coordinate system of the Universe. But it isn't itself a physical thing, just a mathematical model. But the void, the vacuum, the physical things that are contained in spacetime are reasonably seen as having ages, perhaps as old as the Universe, but perhaps not. The oldest stuff in this image is probably the hydrogen that is everywhere- both luminous in the many stars, and the stuff that's there but not visible in an optical image. Just because the stars are only a few billion years old doesn't mean their ingredients are.
Really, Chris? I think the picture at left illustrates what I understand to be at least an approximation of Einstein's idea of matter in spacetime.
People are often asking where in the universe the Big Bang took place. Was it that way, or maybe in the opposite direction? The answer is that everything in the universe has its origins in the Big Bang, including spacetime.
But I see what you mean by the hydrogen being the oldest constituent of the universe. At the birth of the universe everything was so crowded together that it is hard to talk about a void. Perhaps dark energy is what created the void?
Ann
[quote="Chris Peterson"][quote="geckzilla"]If spacetime defines age, then how does it, itself have an age?[/quote]
I don't think it does. Spacetime defines the coordinate system of the Universe. But it isn't itself a physical thing, just a mathematical model. But the void, the vacuum, the physical things that are contained in spacetime are reasonably seen as having ages, perhaps as old as the Universe, but perhaps not. The oldest stuff in this image is probably the hydrogen that is everywhere- both luminous in the many stars, and the stuff that's there but not visible in an optical image. Just because the stars are only a few billion years old doesn't mean their ingredients are.[/quote]
[float=left][img2]https://upload.wikimedia.org/wikipedia/en/f/f3/Spacetime_curvature2.png[/img2][/float]Really, Chris? I think the picture at left illustrates what I understand to be at least an approximation of Einstein's idea of matter in spacetime.
People are often asking where in the universe the Big Bang took place. Was it that way, or maybe in the opposite direction? The answer is that everything in the universe has its origins in the Big Bang, including spacetime.
But I see what you mean by the hydrogen being the oldest constituent of the universe. At the birth of the universe everything was so crowded together that it is hard to talk about a void. Perhaps dark energy is what created the void?
Ann