Is the Big Bang in the Bible?

[Buster's Uncle]

Is Dark Energy Gobbling Dark Matter, and Slowing Universe's Expansion?
http://alphacentauri2.info/index.php?topic=13813.msg62872#msg62872

[Buster's Uncle]

Invisible Dark Matter May Show Up in GPS Signals
http://alphacentauri2.info/index.php?topic=14028.msg63424#msg63424

[Buster's Uncle]

Hey Lori - I never got an answer to my question about the bookkeeping of the universe on relativistic effects - I don't expect you to have a definitive answer, but I can't be the first to ask the question -by about 100 years- and I do rather expect you to know a lot more about the science/theories on that than I do.

SO - a question for anyone who thinks they can wrap their head around it:

The entire universe is expanding - the furthest parts we'd observed when I was a lot younger displayed a red-shift indicating they were receding at about half the speed of light, according to our frame of reference.  So according to the reference frame of a hypothetical inhabitant of the far side of the universe, we're doing the receding, and I suppose the relativistic space/time dilatation balances/cancels out.  Fine.

But imagine that I'm aboard a starship, we'll call it the Unity, heading for Alpha Centauri at 10%C, making for a forty year journey (from an outside "resting" reference point).  The universe has no center -something I don't really understand, BTW- and all of it is moving relative to the rest of it, and the time/space dilation of special relativity is a function of %C - is the frame of reference for relative velocity the average position of the rest of the entire universe, and what/where/how's the bookkeeping to determine relative velocity taking place?

Keep in mind that I'm stupid at math, if you think you know the answer.  I would like a layman's understanding, though.  Please.

...

BTW, I hadn't seen the first episode of new Cosmos yet when I said that about the universe maybe being an in-falling black hole...

I believe that's an intelligently-framed question for a layman (with no formal education in cosmology at all)...

[Yitzi]

SO - a question for anyone who thinks they can wrap their head around it:

The entire universe is expanding - the furthest parts we'd observed when I was a lot younger displayed a red-shift indicating they were receding at about half the speed of light, according to our frame of reference.  So according to the reference frame of a hypothetical inhabitant of the far side of the universe, we're doing the receding, and I suppose the relativistic space/time dilatation balances/cancels out.  Fine.

But imagine that I'm aboard a starship, we'll call it the Unity, heading for Alpha Centauri at 10%C, making for a forty year journey (from an outside "resting" reference point).  The universe has no center -something I don't really understand, BTW- and all of it is moving relative to the rest of it, and the time/space dilation of special relativity is a function of %C - is the frame of reference for relative velocity the average position of the rest of the entire universe, and what/where/how's the bookkeeping to determine relative velocity taking place?

Keep in mind that I'm stupid at math, if you think you know the answer.  I would like a layman's understanding, though.  Please.

When we say something is moving at 0.1c (which is significantly slower than the Unity, by the way; it was slightly under 0.05c), that has to be with respect to some reference point.  Generally, if the speed in question is far faster than the speed of the destination as seen from the source (as in the case of something moving at 0.05c from Earth to Alpha Centauri), you don't really have to specify since it could be either one and the difference would be a rounding error.  But if moving toward something that was itself moving relative to your source at a non-negligible rate, you would definitely have to specify...and the time/space dilation would depend on what you specify.  (Yes, this means that the time/space dilation of an object depends on where in spacetime you are looking from.)

The rest of the universe has nothing to do with the matter.

[Buster's Uncle]

But if the 'other side' of the universe is receding at .5C, our dilation and theirs would be equal and as if no relativistic time effect was ever present, from both frames of reference(FOR) (the space-compression part of the tau effect is another matter, but way too far away to ever hope to measure, so irrelevant), yes?  But wouldn't the Unity, heading at .1C (Yes.  The average is .1C(approx.) for a(n approximately) four light-year journey taking 40 years, QED) towards the far side of the universe (not that it has one, but you know, the oldest, farthest part observable from our frame) in that direction knock the tau factor difference to that FOR to 40%C and therefore seem to be experiencing time FASTER instead of SLOWER from that far FOR as special relativity demands?

The logic indicates that the FOR has to be isolated in the effects, yes, but everything in motion relative to everything else, it's all relative, and the only way to measure speed is relative to other objects/motion and FORs, and --- what IS space?  It seems like the average position/motion of  the ENTIRE universe ought to come into determining what's motion and what's standing still while the rest of the universe moves (like Prof. Farnsworth's FTL drive in Futurama) and determine the dgree of tau in between, but I think I already demonstrated the logical contradiction in THAT.

I cannot accept an Architect taking care of such details, but He (or whatever natural process to blame for the universe) must have put a mechanism into place to do bookkeeping for such things, I think. 

Supper;  brb.

[Unorthodox]

My head hurts now...

[Buster's Uncle]

^Our resident rocket scientist, folks.  I did that to him.

[Buster's Uncle]

-Also, let me be the first to point out my maths error; the relevant velocity of that far side of the universe in the direction of Alpha C. ought to be assumed to be .25C, not .5 - base assumption that the mutual recession is a function of universal expansion and (even allowing for some local variation wherever in between) ought to average out approx. to .25C for our area and .25C for the other side.

This actually exacerbates the degree of the logical tau factor anomaly for the far side FOR by double, not allowing for tau actually not becoming that significant until much higher percentagesC, which is not actually relevant for our purposes.

The brain, it is a little broken but quite large.

[Yitzi]

But if the 'other side' of the universe is receding at .5C, our dilation and theirs would be equal and as if no relativistic time effect was ever present, from both frames of reference(FOR) (the space-compression part of the tau effect is another matter, but way too far away to ever hope to measure, so irrelevant), yes?  But wouldn't the Unity, heading at .1C (Yes.  The average is .1C(approx.) for a(n approximately) four light-year journey taking 40 years, QED)

Wait, did the Unity leave in 2060, or 2016?

towards the far side of the universe (not that it has one, but you know, the oldest, farthest part observable from our frame) in that direction knock the tau factor difference to that FOR to 40%C and therefore seem to be experiencing time FASTER instead of SLOWER from that far FOR as special relativity demands?

Oh, definitely.  If observer A is moving away from observer B at 0.5c, then something moving from observer A toward observer B will (from observer B's FOR) have time pass faster than for observer A itself.

Remember, if two spaceships pass each other moving at 0.2c each, then each will see the other's time as passing slower than its own.

[Buster's Uncle]

But what IS motion?

(I always understood 40-year trip, so 2060.  'Spose you could look it up...)

[Yitzi]

But what IS motion?

Motion is a description of an object's path through space-time.

(I always understood 40-year trip, so 2060.  'Spose you could look it up...)

Santiago was born in 2026, so it must be 2060.

[Buster's Uncle]

Several of those guys are already born, but that's a different conversation.

One thet wood hert mah brane less, but less interesting, too.

[Geo]

Wait, did the Unity leave in 2060, or 2016?

2060. So the average velocity of the Unity was (will be) closer to 11% speed of light (0.11 C), since Alpha Centauri is still about 4.36 lightyears out there. Top velocity must('ve) be(en) a bit higher since there's the acceleration/deceleration phase as well.

BUncle, this 0.5 c receding factor you read about must've been from a time we couldn't see 'as far' into the Universe as we can do today.
Today, what we see of the visible Universe is only what photons from that era have reached us. It must have expanded beyond that time/distance since then, unless the expansion theory is completely wrong.

I think only Aki, Deedee, and Roze must still be born? Can't find a link to that old Firaxis leader biography page right now.

[Buster's Uncle]

You mean YET born?  Haven't kept track.  Domai was recently, IIRC, and I think Zak was in the last six years.

Hmm.  I was thinking an actual distance closer to 4.25ly  -and I did say AVERAGE speed and (approx.)- but the point stands.  I read that .5 around when you were born in an even older text (and I simply do not recall from the mid-70s, when I had no business understanding such heavy stuff, how extensive observations were, re distance/time), and have no idea what the right apparent tau figure is now that we see 13 billion and change out/back.  Again, my point still stands - as long as the logical rigor of the thought experiment holds, my crap maths figures from old data are only examples, as the actual degree of tau is not at issue.

[Geo]

You mean YET born?  Haven't kept track.  Domai was recently, IIRC, and I think Zak was in the last six years.

Just checked with the Alpha Centauri GURPS.  Zak was born in '94. And besides Deedee, Aki, and Roze,  Ulrik, Cha Dawn and Santi must yet be born. Next ones up is Ulrik in 2018.