h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

We are often told that the age of the Universe is around 14bn years (or to be a tad more precise, 13.75bn - +/- 0.17bn years).

We are also advised that nothing can go faster than the speed of light - 300.000km sec; 186,000 miles per sec, or 12 million miles a minute, and that's the fastest speed there is, according to Monty Python.

So, if the Universe measures around 100bn light years across, and the Big Bang was at the centre, surely the diameter (of a 'spherical' universe) should be less than 28bn light years.

I'm no cosmologist or mathemtician, but I think that comes to a little discrepancy of 70bn light years, give or take.

A Great Space-Type Guy once said 'Infinity's quite a ways away, but Beyond encounters a boundary charge'.

Are there any enlightened souls or budding Stephen Hawking's out there who could help clear this up?


AlfieNumerik.

Ah yes, thought I'd come across this before... try
http://www.wisegeek.org/what-happened-after-the-big-bang.htm

(excuse the symbollocs, Brunel doesn't seem to like special characters).

>>
...followed by the inflationary epoch, during which the universe grew by a factor of at least 10power26, and possibly much larger. ... lasted only about 10pwr-32 seconds, but ... the universe grew from the size of a proton to the size of a grapefruit or larger. Its volume increased by a factor of at least 10pwr78. ... expanded many times faster than the speed of light, explained by noting that the space itself was expanding, even though nothing within space broke the universal speed limit.
<<
Noting the last bit (I've removed a 'the'):
>>that space itself was expanding, even though nothing within space broke the universal speed limit<<


Hopefully someone or someones will come along to clarify - and explain!

Isn't there a theory out there that the speed of light is gradually slowing?

Interesting Orcus, don't think I've heard that.


( hmm, meself I reckon it's time that's speeding up. )

Things can't travel through space faster than light. But space can expand faster than light.

yerss, so it seems... and something's just occurred to me:

That link in post 2 says >>Its volume increased ... expanded many times faster than the speed of light<<
What it doesn't say is that the expansion slowed down 'significantly', so might it be that space is still expanding faster than? If so, there's no hope that we'll ever, ever, see back to the big bang, eh?

...and all we need is an external drive - voila!

The original post has the misconception that the universe is an expanding sphere in space with the point of the big bang in the middle. In fact space itself is expanding. However, that doesn't answer the question about the size of the universe.

I found this:

http://space.mit.edu/~kcooksey/teaching/AY5/MisconceptionsabouttheBigBang_ScientificAmerican.pdf
"What does mark the edge of observable space? Here again there has been confusion. If space were not expanding, the most distant object we would see would now be about 14 billion light-years away from us, the distance light could have traveled in the 14 billion years since the big bang. But because the universe is expanding, the space traversed by a photon expands behind it during the voyage. Consequently, the current distance to the most distant object we can see is about three times farther, or 46 billion light-years."