question concerning the plasma in the intergalactic space
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DaveC426913
Valued Senior Member
Most of the plasma is ionized H and He, IOW protons, They will have a positive charge.
Apparently, there is about equal amount of free electrons floating out there, too.
This raises the obvious question: why don't they combine into neutral atoms?
Probably because the plasma is extremely hot (i.e. fast-moving).
This may similar to the earliest epoch of the BB before recombination when the universe was too hot for atoms to form, but I am speculating here.
Они заняты "расширением" пространства... •●
sculptor
Valued Senior Member
Yeh
ok
so maybe that is part of what I had in mind
perhaps
the universe is not expanding from the big bang
perhaps
the space between the galaxies is expanding?
.......................................
If there was a big bang at the beginning,
does that not imply a center of the universe?
and, if so
where is that center?
ok
so maybe that is part of what I had in mind
perhaps
the universe is not expanding from the big bang
perhaps
the space between the galaxies is expanding?
.......................................
If there was a big bang at the beginning,
does that not imply a center of the universe?
and, if so
where is that center?
Wizard of Whatever
Registered Senior Member
Google AI:
In most cases, the number of positive charges (from ions) is roughly equal to the number of negative charges (from electrons). This state of near-neutrality is referred to as quasi-neutrality
In most cases, the number of positive charges (from ions) is roughly equal to the number of negative charges (from electrons). This state of near-neutrality is referred to as quasi-neutrality
exchemist
Valued Senior Member
No. There is no centre.
If the space between the galaxies is expanding, then the universe is expanding. Isn't it?
All the evidence suggests that there was.
No.
A better mental image of what's going on is to think of the universe as like a loaf of raisin bread, with the raisins representing galaxies. As the bread is baked, the entire loaf expands, and each pair of raisins in the dough moves further away from all the other raisins. THe universe is just like that, only we can't detect any "boundaries" to the "loaf". The loaf has no edges and therefore no centre. The raisins (galaxies) are spread around somewhat evenly, if you consider things on a large enough scale.
There is a centre to the part of the universe that we can see. That centre is right here, at the Earth. But if you lived in a different galaxy, that galaxy would be the centre of your visible universe, instead.
DaveC426913
Valued Senior Member
The problem I find with the raisin bread analogy is that it falls apart almost immediately. Raisin bread has a crust - a boundary - and the raisin dough expands into a larger space.
I prefer the model of ants walking around on an inflating balloon. Their entire universe is the surface of that balloon. A few things these ant scientists note:
- distant things in their universe appear to be moving away from each other. The farther away things are from each other, the faster they are moving away.
- This does not happen with bound objects (by gravity or inter-atomic forces) - such as ants and ant-planets. They are unaffected the expansion, which is far too weak to operate on them. The spreading only seems to affect objects unbound to each other (such as ant galaxies unbound by gravity).
- they can walk around their universe forever and never find an edge
- they can project the balloon's size backward in time until it was smaller than an atom, yet it still has no centre. When it expands, it expands everywhere at once.
And, in case, you're thinking "well the centre of that universe is inside the balloon", no. A 2-dimensional surface does not need to be embedded in a 3D universe to be finite and unbounded. It does not need to have a centre.
Think of a video game where you can disappear off the top of the screen and reappear on the bottom, or disappear off the left side of the screen and appear on the right. This is a 2-dimensional, finite-yet-unbounded universe that has no preferred centre. (Not a strong analogy, just an example).
The same thing can exist in three dimensions.
I prefer the model of ants walking around on an inflating balloon. Their entire universe is the surface of that balloon. A few things these ant scientists note:
- distant things in their universe appear to be moving away from each other. The farther away things are from each other, the faster they are moving away.
- This does not happen with bound objects (by gravity or inter-atomic forces) - such as ants and ant-planets. They are unaffected the expansion, which is far too weak to operate on them. The spreading only seems to affect objects unbound to each other (such as ant galaxies unbound by gravity).
- they can walk around their universe forever and never find an edge
- they can project the balloon's size backward in time until it was smaller than an atom, yet it still has no centre. When it expands, it expands everywhere at once.
And, in case, you're thinking "well the centre of that universe is inside the balloon", no. A 2-dimensional surface does not need to be embedded in a 3D universe to be finite and unbounded. It does not need to have a centre.
Think of a video game where you can disappear off the top of the screen and reappear on the bottom, or disappear off the left side of the screen and appear on the right. This is a 2-dimensional, finite-yet-unbounded universe that has no preferred centre. (Not a strong analogy, just an example).
The same thing can exist in three dimensions.
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А в чём, по вашему мнению, находилась эта первоначальная Вселенная? В чём она болталась?
I mentioned this difference, explicitly, in my post where I brought it up. Did you not see that?
Sure, the raisin bread analogy has that problem of the loaf having a boundary, unlike the universe, but it also has the advantage of being a three-dimensional analogy rather than a two-dimensional one that requires a person to extrapolate the reasoning into the third dimension.
This is the two dimensional analogy. In my own experience, I have found that non-mathematicians often seem to have trouble making the mental leap from the 2D analogy to the 3D reality.
The 2D analogy has its own strengths, too. Which just goes to show that one should not be overly reliant on any single analogy, but rather flexible enough to use whatever analogy is best suited to the purpose of the moment. Ultimately, no analogy is going to be a perfect substitute for considering the real thing in all its complexity. Analogies aim to give a simplified picture. In doing so, they all inevitably lose some features of the thing they are modelling.
foghorn
Valued Senior Member
Every point in a spacial expanding universe is the centre of its own observable universe.
There is no need for an absolute centre.
Sculptor, you and I, are each at the centre of our own individual spacially expanding observable universe, but given the scale of things, we conveniently agree the earth is the centre for both of our observations.
If I stayed on earth, and you were to go 46 billion light years from earth, then we would still be at the centre of our own individual observable universe, but not the same one.
We would then 'share' half an observable universe in the direction of each other. (I Think)
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Pinball1970
Valued Senior Member
I would read about Voyager, those probes are still sending back data on the interstellar medium.
Some of the on board instruments are still operational.
Voyager 1 - Wikipedia
DaveC426913
Valued Senior Member
Sure. But all you did was mention it. In my view, it's a big enough flaw that it eliminates the usefulness of the analogy.
I think that brain-stretching extrapolation is critical. There's no mundane analogy of TBB and the expanding universe. Providing a mundane analogy such as raisin bread simply reinforces the naive idea that the universe has a boundary and need a space to expand into.
Sure. But if the ants-on-a-balloon analogy goes too far, the raisin-bread analogy doesn't go nearly far enough. Worse, I fear it cements the erronous idea of a centre and a boundary.
Anyway, more is better, of course. As long as the listener/reader sticks around for the "more", and doesn't just go running off wth the raisin bread analogy by itself.
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foghorn
Valued Senior Member
Yes, people should use their loaf with the raisin bread analogy.