How is the Universe Expanding?

[bennyboy]

*Seizes Alex by the collar, boggle-eyed and fearful*

So where's the extra space coming from Alex?! WHERE'S THE SPACE COMING FROM?!?

Duude chill out! You can simply picture everything in fixed space shrinking if that helps.

I thought about that.  That would account for red shift too, methinks, even if nothing was moving at all, n'est-ce pas?  At least. . . assuming that photons weren't scaling down with everything else?

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. . . errmmm. . . is that a thing?  It sounds to me like something that isn't.  

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Alex, if space is expanding, wouldn't the rate of separation of objects be a function of their original distance from each other?  I mean, if I put two dots 1cm apart on a rubber sheet and stretch it to 2x its original size, I'd expect them to be now 2cm apart.  But if I put them on opposite edges of a 1m sheet, I'd expect them now to be 2m apart-- a 100x difference in the apparent rate of separation even thought the original rubber "Universe" is expanding in exactly the same way both times.  But in the 1cm apart dots, it seems it wouldn't matter WHERE on the sheet they were-- near the middle or right up near the edge-- the apparent change in position relative to each other would be identical, no?

In other words, from one of those dots, I don't think I could necessarily figure out where the center of the rubber sheet was based on the changing relative position of any of the other dots.  So. . . how do they arrive at the Big Bang singulariy, rather than on a position that the Universe just expands forever and ever?

Once the gravitational wave detectors detected gravitational waves, the whole gravitational wave thing took on quite a bit of credence.

As for how long it will take the sun to spiral down into the core of the galaxy?  Be thinking a very long time.  I suspect your growing finger nails would get there first.  (sorry, I'm not going to do the math)

But wait. . . since gravity binds all things, wouldn't gravity "energy" coming into a given system (say, a planet) literally have to be 100% identical to that going out?  Like, including the detector? And wouldn't each and every particle have already established that mutual energy-sharing link in a kind of grand entanglement at the beginning of time?

[Alex K]

Everything that Alex said but he didn't touch on some of the implications. The expansive force is increasing space at a rate equivalent to a speed greater than the speed of light. That means we're living in a curious time when we're lucky enough to still be able to detect other galaxies. There will come a time when conglomerations of matter will be so far apart, an observer in one would see no others. Cosmology would be all but impossible. This will happen long before the heat death of the universe, too.

In related matters, the latest experiments to discover the Inflaton, the elusive particle predicted to be responsible for universal inflation, have failed so utterly as to rubbish all predictions. The Inflaton, if it exists at all, is nothing like it needs to be to make our current models work. That means our current models reliant on its existence are probably utterly wrong.

Experiments to detect the inflaton have ruled out inflation models? That's the first I hear of that, which experiment do you mean?

[Ben Davis]

Experiments to detect the inflaton have ruled out inflation models? That's the first I hear of that, which experiment do you mean?

Hey Alex, I'll look it up and post a link

[Rhondazvous]

Everything that Alex said but he didn't touch on some of the implications. The expansive force is increasing space at a rate equivalent to a speed greater than the speed of light. That means we're living in a curious time when we're lucky enough to still be able to detect other galaxies. There will come a time when conglomerations of matter will be so far apart, an observer in one would see no others. Cosmology would be all but impossible. This will happen long before the heat death of the universe, too.

In related matters, the latest experiments to discover the Inflaton, the elusive particle predicted to be responsible for universal inflation, have failed so utterly as to rubbish all predictions. The Inflaton, if it exists at all, is nothing like it needs to be to make our current models work. That means our current models reliant on its existence are probably utterly wrong.

Not necessarily. Whatever force is causing this inflation is very different from the forces that affect particles and energy. We know this because the movement is different. The rubber band is moving outward, while the particles and energies we observe move in circular, elliptic or spiral orbits around some center.

Just because Einstein's curve may not apply to the expansion, doesn't mean it's useless in explaining the orbital world. Scientists haven't thrown the standard model out because it's still useful in its own sphere. In the meantime, we search for the holy grail—a grand unified theory that has no sphere.

[Crunchy]

I know the galaxies are moving away from each other, but the levels of the universe are somewhat fractal. so are the stars inside galaxies moving away from each other? Are the plants around stars moving away from each other?

2. Since the expansion is a result of the big bang and there were no atoms at that point, at oms would not be a part of the expansion. In fact, the formation of atoms appear to be a reversal of the expansion.

Distances are stretched through the expansion of space. It's as if space itself is stretched..You can think of it like ants walking on a rubber band that is being stretched.  
Two separate ants will move away from each other through the stretching, but the ants themselves keep their length because they are held together by forces which are not changed by the expansion of the rubber beand.
Likewise, in space, all objects which are held together by forces such as gravity or electromagnetism will resist this stretching and keep their sizes because their size is determined by these forces at work in or between them. Two distant objects which are not e.g. bound by gravitation will not have anything compensating the stretching of the space in between and their distance will increase.

I like to think of it like a raisin bread that is rising. The raisins are the galaxies and the dough is "space". As the bread rises, all the raisins are moving away from each other. The only difficulty is in imagining empty space as something that can expand.

[Rhondazvous]

I like to think of it like a raisin bread that is rising. The raisins are the galaxies and the dough is "space". As the bread rises, all the raisins are moving away from each other. The only difficulty is in imagining empty space as something that can expand.

Once I realizes that space is not empty, that difficulty vanished. Your raisin bread analogy is apt.

[vorlon13]

Once the gravitational wave detectors detected gravitational waves, the whole gravitational wave thing took on quite a bit of credence.

As for how long it will take the sun to spiral down into the core of the galaxy?  Be thinking a very long time.  I suspect your growing finger nails would get there first.  (sorry, I'm not going to do the math)

Come on, third derivative of the quadrupole moment, don't be a wuss and grab your pencil

fucking Besselian elements always trip me up

[bennyboy]

Come on, third derivative of the quadrupole moment, don't be a wuss and grab your pencil

I just googled "third derivative of the quadrupole ," and even looked up a couple papers.

Fuck you, Alex. Just. . . fuck you!

[The Valkyrie]

Edna, the Eternal Sweeping Lady, is sweeping away nothingness so the universe can expand into it using Her Broom of Eternity. She is everywhere at once, at the edge of the universe, sweeping away eternally.

Fear the day She takes a break...

[Rhondazvous]

Edna, the Eternal Sweeping Lady, is sweeping away nothingness so the universe can expand into it using Her Broom of Eternity.  She is everywhere at once, at the edge of the universe, sweeping away eternally.

Fear the day She takes a break...

And dread the day she decides to use a Hoover.