Is the Universe the Size of a Grapefruit?

[Skolon]

Hold on, 1 billion = 1,000,000,000, so 13.7 bn years minus 350,000 years is not 13.3 bn years! It's 13.69965, which is close enough for me!

Yes, you are right, I was wrong. The 13.7 billion is the correct value.

 

[Chronos]

Obviously the universe is 'now' much larger than 13.7 bly, how much larger is unknowable, imo. It would require knowledge of the speed of exansion NOW across all spacetime intervals. I fail to see how this is possible to achieve. Size based on light travel time, however, is an empirical measurement.

 

[S.Vasojevic]

One thing is not clear to me though, is Hubble law calculating distance as we see it (light travel time), or "now" time. Because when you plug C for recession velocity you get distance of 13.7 Gly, so it appears to me that it calculates distances based on light travel time.

 

[justwondering]

I have read in many places that the universe was once smaller than an atom. However, many people here have said this is a 'cartoon' version of the big bang theory. And that the media have popularized this invalid notion...

I now have some questions, can I have the 'true' answer (what we know now) and not the cartoon answer please :)

1. Was the universe the size of a grapefruit at some point in the distant past? (some say the observable universe was, but if the observable universe is isotropic, then surely the whole universe is basically the same? And therefore the whole universe must have been small in the past)

2. What is the shape of the universe?
(I've read that it is probably flat)

3. Is the universe infinite? (If the universe is 'space' there surely can't be an infinite amount of it? but I guess the universe is space-time, and time in theory can go on forever?)

4. Why isn't the space between me and my bed expanding? Why isn't the space between my atoms in my body expanding?

5. Is my body made of dark matter? What is made of dark matter? (I've read that dark matter makes up empty space, but my body has empty space etc...)

Sorry if my questions are dumb. I would just like to get a better understanding of what the general concenus among scientists is.

Thanks!

"I have read in many places that the universe was once smaller than an atom."

Said to be even smaller than a Proton at one instant! It just gets sillier and sillier!

 

[friend]

"I have read in many places that the universe was once smaller than an atom."

Said to be even smaller than a Proton at one instant! It just gets sillier and sillier!

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.

 

[mikeph]

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!

 

[Chronos]

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.

 

[friend]

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.

 

[mikeph]

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.