Is the Universe the Size of a Grapefruit?

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In summary, the conversation discussed questions about the size, shape, and composition of the universe, as well as the concept of expansion and its effects. It was noted that the observable universe was once the size of a grapefruit, but the total universe may be much larger or even infinite. The shape of space is considered flat, and the idea of expansion causing a change in temperature or the potential for energy extraction was brought up. It was also clarified that dark matter makes up most of the universe, but it is not the same as the matter that makes up our bodies. However, the concept of dark energy was also mentioned as something to watch out for.
  • #36
friend said:
If the universe did not come from a singular point, then that brings up questions of causality; how could everything come from absolutely nothing? But is easier to think that the universe came from nothing when if it began from a singularity, because a singularity can be considered nothing, since there is no dimension to it.

This is certainly not the big bang theory... do you have anything to support this? It seems like nonsense!
 
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  • #37
Light travel time is not a certainty either. You must accept that GR and redshift correlation to distance is correct. These appear to be good bets, but, not proven - nor will they ever be. BB is basically an extrapolation of GR. Since GR is not absolutely proven, any extrapolation is even more uncertain. Most scientists recoil from any therory that predicts infinities in nature. It indicates the theory is unreliable at that level.
 
  • #38
MikeyW said:
This is certainly not the big bang theory... do you have anything to support this? It seems like nonsense!

If the universe always existed, then that's the same thing as saying that there's no tracibility to its ultimate cause. It's a denial of cause and effect. It's the same as saying that the universe is illogical and not reasonable. If the universe started from a finite size, then this is the same problem; it only differs in a matter of scale. You're still saying that some finite size universe always existed. Since you cannot trace it back to a time before that, you're saying it always was. So the only way cause and effect remain tracible from the beginning of the universe is if it started from a single point. This is not to say that some things have infinite value at the single point, only that it must have started from a single point.
 
  • #39
I'm not debating it, I'm asking for a source... I don't think it is appreciated in this forum to set out and defend personal theories.
 

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