Expanding space?

Gravity bends space. We can see this practically by light being bent when it goes close enough to a star yet it is not in an atmosphere. Space has a structure of some kind which probably dictates the cosmic speed limit of EMR and gravity. Some people have taken to calling it aether, after the old idea.

However in an expanding universe, space itself is expanding continuously (unless more of it is being made which sounds unlikely). Over billions of years, the universe (as in space) is said to have gone from a point source to 158,000,000,000 light years across.

But how can this happen without huge changes in the structure of space as it endlessly becomes "ever less dense" for want of a better term? Surely if space were really expanding, the speed of light would continually increase, atomic forces would decrease, etc and the universe would have ceased to exist long ago?


A question I asked on another forum. Is space expanding through 3 or 4 physical dimensions? (forget time as 4D for now). 3D would be like a solid ball expanding and a definite centre to the universe. 4D would be a hypersphere, like the balloon model used to explain galaxies becoming ever further apart.

 

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That's science fiction as far as we know in todays astrophysics.

If more space isn't already there then how do account for it continuing to

expand? If it started with a pinpoint and is now as large as you say then

wouldn't it be possible that there's more space there already for it to keep

expanding until it reaches a point where it collapses in upon itself as it could

have done over and over throughout time?

 

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Well, to begin with, your number is completely inaccurate. The best current estimates/measurements place it at 98 billion light years across, not the 158 billion you stated.

The thing is, you MUST include the 4th dimension as a part of the expansion because it isn't simply "space" that's expanding - it's actually spacetime. The two factors - space and time - are so closely interwoven that they are inseparable. That's a common mistake, though, many people don't understand that at all.

There's absolutely no reason to even suspect the changes you suggested. What makes you even think that would be the case??

 

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cosmictraveler. Though it is denied, 4D is what is needed for the classic idea of an expanding universe. 3D have a definite centre which the universe is expanding away from.

My point is that even if space is endlessly elastic, it would become "endlessly thinner" (for want of a better phrase) as it expanded. That should have some effect on the universe at the most basic level.

A collapse would suggest an elasticity which I don't think space has, at least on the necessary scale.

 

Read-Only. I was just quoting the wiki figure which has been quoted to me in the past. If you say 98 billion instead, OK because I don't believe that either.

Spacetime? As in using a TARDIS to get to the Moon? That's mathsworld. There is real space and man-made time as well as the time dilation delusion.

The trouble is that many are happy not to think for themselves and just go along with the standard model. As my signature says, nothing is beyond question. There can be no sacred cows in science.

 

Sorry, but you are badly mistaken - either through having been mislead or the result of not understanding due to lack of study.

Time dilation has been proven again and again through careful experimentation and I seriously doubt that you hold the credentials to refute the work of many, many professional scientists all across the world.

As to spacetime, I suggest that you go away and do some serious study on the topic. You certainly have a LOT to learn and will find that exercise to be both educational and interesting.

 

Read-Only. A text book quoter. They're fun. For starters:

Take an atomic clock. Put it in a car and take it to the airport. Put it in a plane and zoom down the runway at nearly 200 mph before take off. Get up to cruising altitude and then fly around some. Reverse the procedure till you get back home and check it out against an atomic clock that has been left sitting on the mantlepiece. Amazing! They are different. Of course all that activity would not affect a flow of heated cesium atoms in an atomic clock.

Heavier gravity slows down atomic movement (or do you think it works by magic). Wow! Time dilation. Not.

You speed something up, time moves slower. You cool something down to almost absolute zero and does time move faster? If not, why not?

Spacetime is maths world. Prove to me that time exists in the real world.

 

Both speed and gravity affect time in independently, yet cumulative ways. I provided you with a starting link in the other thread that spends some effort discussing both of those effects. Once you've read that and done some more research on your own, then come back and tell us what you've learned.

 

Anyone heard of Friedman's equation?

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It basically describes expansion of universe as a result of big bang...


and than Einstein added a cosmological constant to make the equation:

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(I am currently adding meanings of constants and eq. descriptions)

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Yeah so basically

Friendman's equation constants/variables:

density constant: p
gravitation constant: G
Hubble parameter: H
scaling parameter: R
curvature parameter: k

 

I presume you have read the site you quoted and yet it has not provided you with sufficient information to answer a single one of the points I have raised. Go get an education then come back to me and maybe we can engage in debate.

 

dragon. With so many unknowns and so much guesswork, what is the value of such equations based on that?

Einstein couldn't even see that the double slit experiment was a simple illusion.

 

Actually, I've no interest in debating anything so trivial with you. I'm a retired researcher with a few degrees and I've been through all of this way back in college in the 60s and 70s.

The fact you cannot grasp or understand it is your problem - not mine. It's quite obvious that you cut your education far too short to even begin talking seriously about the topic. I therefore suggest YOU take your own suggestion and put some additional time into bringing your own degree of learning up to at least 1950s levels. As of now, you are far, far below that. You presently have nothing to show the people here because of that severe handicap.

 

Then enough said.

 

Read-Only. You utter the most tedious boasts. Anyone on this forum can claim to have attended universities, gotten degrees and doctorates but the ultimate test is what we post here and all I have seen from you is schoolboy insults to me and others. That appears to be the limits of your education.

 

I'll break my self-imposed silence with you one time in order to make myself clear.

You are totally incorrect: what we post here is no test at all and of no real consequence at all. The ultimate test is what we've done with our lives in the real world.

If you actually had anything of value to offer I would not hesitate to debate or support you until the end of time. But you have nothing other than ego - therefore I will make no effort toward you.

As I said, once you tire of not getting any attention for your erroneous views, you will eventually go away and will not be missed by me nor anyone else.

Enjoy living in ignorance.

Goodbye.

 

Read

You also retained for me the same impunity. Remember, when i was a freshmen here?

Have more humainty friend. He is a friend of mine, and if you are also a friend of mine, let's all be counterparts.

 

The equation basically says: Is there enough gravitating stuff in the universe to balance out the currently observed expansion rate? If not, the universe will go into a "big stretch". If there is more stuff than expansion, "big crunch". If both cancel out (as they apparently nearly do), then the universe is steady. This is related to the works of Friedmann, Lemaitre, Robertson and Walker. I'm not sure if you were asking seriously or not, but I thought that I would answer anyway.

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A consequence of the calculations I did in the other thread gives the critical density (mistakes notwithstanding) as:

rho = 3/(4 pi) * (H^2 c sqrt(5)^4)
rho = 0.238732 * 7.49481e9 * H^2
rho = 1.78925e9 * H^2
rho = 4.58049e-27 kg m^-3

Not a lot of stuff per cubic metre, but it's nearly what we find in observation.
Reference: http://www.schoolsobservatory.org.uk/study/sci/cosmo/internal/critdens.htm

Oh, and another thing.... TETSUOOOOOOOOOOOOOOO! Sorry, I had to do it!

 

I don't understand what this leads to?

 

I was just showing Kaneda the critical density that gives the Einstein de-Sitter universe, which is very close to what we observe. I wasn't sure if he was honestly asking about the Friedmann equations or not, but I thought I would give him some information anyway. The result is pretty much identical to the original form of the equation, but without G and twice the steradians in the mix to confuse things.

 

I remember quite well. I also choose my own friends. I consider you to be close to being one but he will never be. I do not tolerate those who's egos are so large that they think they know more than all the professional scientists of the world combined. That's total ignorance and rather infantile.