How Big is Space?


A recent “Frontline” program speculated that there's probably an abundance of life in the universe, and said the task of hunting for it is becoming better focused.
I've often wondered how big it is, and so did a certain 13-year old Dane. Astrophysicist Paul Butterworth offered a good answer here. Notice his footnote: we can only “see” out about 10 billion light-years, so we know it has a radius at least that big, but if may be bigger yet.
However, that set my contradiction-detector a-jangle. If nothing can move faster than light, how could rocks travel further than 10 billion light-years in only 10 billion years?
More: those stars we can detect on the edge, 10 BLYs away, must have taken longer than 10 billion years to get there; hence to arrive and be seen must have taken more than 20 billion years, round-trip. Yet the Universe is thought to be no older than 15 billion years.
There's something fishy going on. Is Hoyle's Steady-State theory about to stage a comeback? Was Einstein mistaken about the speed limit?
Inquiring minds would like to know.


ReverendDraco's picture

Well. . . as near as I can tell (and, granted, I'm an autodidact when it comes to physics). . . from the first few Planck Times until the space-time continuum settled down, everything expanded at many times the speed of light - hence, a universe much larger than the amount of Continuum Time that has passed would allow for.

Einstein wasn't mistaken. . . Matter is nothing more than condensed energy - there is nothing in Einstein's theory which claims that energy cannot exceed the speed of light - only matter.
During the Plank Times (and certainly a bit into Continuum Time) the universe contained, in an area of quantum compactness, "infinite" energy - the same infinite energy Einstein posits is necessary for matter to achieve FTL speeds.
So, the matter which constitutes the stars and rocks *could* have traveled (and did travel, in all likelihood) at many times the speed of light in the earliest instances of the universe - both as energy, and, as energy coalesced into matter, as matter propelled by "infinite energy."

This inquiring mind had to know. . .

Jim Davies's picture

Thanks, ReverendDraco! So I wasn't the first to notice the anomaly, and the Big Bangers have explained it by positing an exception to the general rule that "c" is a constant, to apply just in the earliest moments of the Bang.
It still smells fishy, to me. However could that theory be tested? And I had thought that Einstein's theory did propose that light - certainly a form of energy - could not exceed the speed limit of c.  But I'm several decades out of date, and in physics that's a very long time. String theories get me really strung out.
I wonder further: if c is actually variable (by "many times") then c squared would be capable of huge enlargement; and so the energy produced in a nuclear explosion could perhaps become ten or a hundred times greater than anything yet seen. Great! Just what the world needs - a super super government bomb.

ReverendDraco's picture

As I understand it, c was only a variable until the basic laws of physics were set. . . until such a time as there *was* time.

Dagnabbit. . . I recently watched a documentary about it - which was why I sort of had an answer ready, even though my non-typing fingers made a few mistakes in the explanation. . . I'll try to find it again.

Jim Davies's picture

I thought "c" was chosen to denote the speed of light expressly because it is "c"onstant, in English; but now you have fingered yet another profound question: time, and what might be meant by time "beginning" and/or "ending." And are you saying that the basic laws of physics were set some finite time after the Big Bang began? But that would make it illegal! Arrest that man!
I noticed last year that even the good book seemed to get its knickers twisted about time; possibly, Reverend, you can unscramble the knot. Genesis 1:1 and John 1:1 (for example) state that there was a "beginning," whereas Psalm 90:2 reveals that there was not; "from everlasting to everlasting..."
Dagnabbit, indeed.

Glock27's picture

Space is about as big as someone wants it to be and about as old as they believe. I don't believe there are any rules of reason on beliefs. If I believe it to be true there is no persuasion which will change my mind until I see that I am wrong. I am curious about "infinity", and is there really anything constant?