How can the universe be expanding?, page 2
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reply posted on 7-1-2011 @ 02:04 AM by Kayzar
reply to post by yaphun




If we have a hypnosis or theory it must be testable. It is a pretty good way to do this is by asking "if [insert theory here] is true" we can predict the answers.


Yes but not in this case.A hypothesis is a proposed explanation for an observable phenomenon, for example:
If i eat my poop then i will vomit
A theory is an explanation of reality that has been thoroughly tested so that most scientists agree on it.
Big difference, which is why you will never hear about Kayzar's theory of poop vomit.



A few examples ..

- If [evolution] is true we should never find a rabbit in the Cambrian period.
- If [evolution] is true we should find a reason why humans have 23 pairs of chromosomes but all other hominids have 24 pair.
etc etc

Horrible examples...


David Scott should be able to fly to the moon and drop a feather and hammer at the same time and ...
If [gravity] is true they they would hit the ground at the same time.

Another horrible example, he just prooved law (not theory) of universal gravitation to be correct, big whoop.


reply posted on 2-7-2011 @ 09:15 AM by SugarCube
reply to post by Hefficide



I'd just like to comment on the 'centre of the universe' issue. Just because 'everything' is moving away from us, it does not mean that we are stationary in the context of all other movement.

As an example. Imagine a set of traffic lights where three cars are lined up. The lights turn green and the all the cars starting driving along a straight 3-lane road. Each car travels at a different speed, we'll call them slow, medium and fast. After a period of time, the relative positions would be something like this:

START
---------------------------->S (slow)
----------------------------------------------------> M (medium)
-------------------------------------------------------------------------------> F (fast)

The point is, M is quicker than S and F is quicker than M. It is obvious that F is moving away from M, leaving it in the dust trail, however, from the relative context of M, S also appears to be moving away in the opposite direction to F.

Relative speeds

S (slow) <---------- M (medium) ------------------------------> F (fast)

If you ignore the fact that S, M and F are all moving, then it could be assumed that M is stationery and S is simply moving away slower from M that F, both in opposite directions.

Perhaps somebody would like to comment on whether celestial objects are heading away at a lower speed from the Earth than objects on the opposite side?




edit on 2-7-2011 by SugarCube because: (no reason given)



reply posted on 19-7-2011 @ 01:10 PM by Denali
reply to post by Firepac



Did you read anything that anyone posted? This thread has absolutely nothing to do with how far the universe can expand, its about whether or not it actually is expanding.


reply posted on 19-7-2011 @ 01:37 PM by CLPrime
Maslo has answered the OP's question well enough... but there is one thing I want to reply to...

Originally posted by VariableConstant

I have a very intelligent friend who asked me a good question the other day, as we were debating the currently accepted theory as to the creation of the universe. He talked about black holes, which as far as we know are nothing more that incredibly dense matter that have such a pull that nothing can escape from them, not even light. So if you consider that, according to the bang theory, all matter in the universe, including all the stars, collapsed or otherwise, along with all the planets and everything else, were once concentrated into a "primordial egg."

This ball of matter would contain everything that currently makes up our universe, and would therefore have a mass and density beyond our ability to comprehend. Its gravitational pull would be inescapable. So how could anything ever escape from this central point, regardless of the violence of any explosion?

I'm not an astrophysicist, so maybe someone else would be able to answer this, but it seemed like a pretty good question to me.


Your friend should familiarize himself with cosmology theories that aren't 60 years old.
The current "Big Bang" theory is, in fact, not a Big Bang theory at all. It's called LCDM (Lambda - Cold Dark Matter) Cosmology. "Lambda" refers to the Cosmological Constant of Einstein's field equations, which is responsible for the expansion of the universe and is the mathematical description of what is now called Dark Energy. "Cold Dark Matter" refers to the addition of additional matter-density that is undetectable by traditional means, and is responsible for anomalous galaxy rotation curves.

LCDM says that, in the beginning (so-to-speak), it was very possible that the universe was infinite. In fact, my preferred view is that the universe was an infinite void, containing nothing at all. The difference between this empty universe and our current universe, though, is its level of zero-point energy. This energy is found in Quantum Mechanics, and is the energy contained within a vacuum. That is, in QM, a vacuum is not a region containing absolutely nothing, as we often consider it to be - a vacuum is, in fact, a region having the lowest possible energy level. I tend to liken this to walking on the ground. When you walk along the ground, you are effectively at your lowest possible energy level. But, what happens if you happen upon an abandoned mine shaft and fall through? Suddenly, your once-"lowest possible energy level" has collapsed to an even lower "lowest possible energy level." Essentially, this is what modern cosmology says occurred within that original universal void.

When the vacuum of that initial void spontaneously collapsed to a lower energy level, the potential (zero-point) energy it had been containing was released, and this massive release of energy is what drove that initial sudden period of rapid inflation (during what's called the Inflationary Epoch). Eventually, once the energy had dissipated enough for the inflation to slow significantly, the universe was allowed to cool, and the energy condensed to form particles and, ultimately, matter.

This is the current theory. Now you can bring your friend up-to-speed.
edit on 19-7-2011 by CLPrime because: (no reason given)



reply posted on 20-7-2011 @ 04:38 PM by AncientShade
The easiest questions are most of the time the most difficult onces to explain. This question is no different.

Certainly, I could talk about the big crunch or the infinate expansion. But let's ask ourselves a little different question;

We see the universe expanding, but what is behind that wall of dark matter that originates from the primordial blast?

If the universe is expanding we can assume that the outward force generated by the primordial 'big bang' is bigger than the resisting force on the other side of the wall. Maybe it is expanding into nothingness and thus creating something?

Ofcourse that is not true. Nothingness can't exists unless absolutely nothing exists including the not existing of our universe. So we must state that at least something exists, somthing that has less matter density per square inch than our universe has as an outside pushing force. That would be, very light maybe even negative towards our own universe.

Let's assume for humor sake that it is negative, this would create a sucktion effect, much like a drain seems to suck water. Essentially it would mean that expension was accelerating. if that were true than eventually we would end up with one molecule evere hundred lightyears and no more planets and stuff.

If it is lighter but not negative than it would ultimately form a barrier, this compressed barrier would be like a wall, potentially between many 'universes'. Possible, but there needs to be an end somewere.

I guess the real limitation here is not so much what is behind the wall, but more how far can we stretch our mind.


reply posted on 21-7-2011 @ 05:34 AM by MrXYZ
reply to post by Nostradumbass



It's factual because we can analyze the light coming from stars and galaxies. If the distance between the light source and the observer increases, a redshift takes place as the wavelength of the light increases. We can observe this redshift everywhere, so that's why scientists say the universe is expanding.

LINK
edit on 21-7-2011 by MrXYZ because: (no reason given)



reply posted on 25-7-2011 @ 10:08 AM by CLPrime
reply to post by Firepac



I'm not really sure how much better a hypersphere analogy is at visualizing the expansion of the universe.
Personally, I prefer the raisin bread illustration.


reply posted on 2-8-2011 @ 01:31 AM by Akasirus
reply to post by Kayzar



I don't know where you are getting that definition of theory, but it's incorrect. There is no requirement that a theory must be supported by 'most' scientists., or even anyone at all. If that were the case, we wouldn't be able to have dozens of competing theories in fields such as string theory as we do now, as none of them would be able to gather the required support.

Basically, it's a hypothesis until you have any data to support. At that point, you can call it a theory if you want. A theory in science is simply a proposed explanation whose status is still conjectural. It doesn't have to be popular, it just has to be falsifiable (I.E fit inside the scientific model) and fit currently observed data. Once it is falsified, it's no longer an active theory. Theories rarely ever get verified, simply because it is difficult to prove something absolutely without infinite data.

But that said, simply because it's a theory does not discredit it. Gravity is a theory. It is very hard to verify something absolutely without an infinite set of data. The universe IS expanding, at least according to out current knowledge. It is a sound theory, and it would require a major change in our understanding of the universe if it was disproven away.

I don't understand why we would have to be the center of the universe to notice expansion, that's just absurd. Imagine if we are in a race, and there's a starting line. 3 cars start at the same time, one going 45mph, one going 60mph, and one going 75. We each are getting further from each other at varying speeds, and if we are the car going 60mph, we certainly know we aren't staying still, and we can tell the common vector is not our position, but the starting line.

From our position it would appear as if everything is radiating out from us, in the same way people on the platform appear to be moving when you are in a speeding train. To me, assuming either of these things is equally foolish.

edit on 2-8-2011 by Akasirus because: (no reason given)

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