Recent content by gruff

Hi Just finished the chapter on the Multiverse in David Deutsche's excellent book The Beginning of Infinity. His explanation of how discrete values change from the multiverse perspective is brilliant. In it he explains that there is no such thing as a 'quantum jump' and that what 'changes'...

Hi I have an installation/art project that requires a rig designed to balance a weight of 3200lbs using a weight of 30lbs. I think that means a mechanical advantage of 107 if using pulleys? Both weights would be suspended in the air by the rig so that someone pulling on the small weight would...

But doesn't Boltzman's argument assume an existing (albeit timeless) physical universe in order to determine likelihood of fluctuations in it?

OK, I think I understand you: it presumes an exiting physical universe, the thermal bath, with no arrow of time.

I think Dmitry67 is more convincing so far. Chalnoth, doesn't the Bolzman argument presume a classical background time and so your framing of it slips in the need for causation arbitrarily. Isn't this begging the question?

Thanks for the lesson in the scientific method but I understand that already ;) I was indirectly asking what physics would falsify it, whether is a case of being 'not even wrong', rather than philosophical objections. [There are lots of other hypotheses that deal with why the BB occurred...

Hi Dmity67. It's like the North Pole analogy: every direction from the NP is south. Likewise every time from a BB is the 'future' but there are only two paths to take. I'm not a physicist so I can only think philosophically about it. But I'd like to know more.

Yes. Like the number line with 0 in the middle. From the point of view of observers on either side of the BB there appears to be a beginning to the universe but there is no such thing. It would simply be an artefact of the arrow of time on each side.

I've been reading Julian Barbour's excellent book 'The End of Time' which is based on his work on foundational issues in Physics (specifically time and space). I like his ideas a lot, however I'm sure I read in it a description of the big bang which was in reference to Mach, I think, that showed...

Right. You can't treat the time dimetion like a space dimention, because space is not the same as spacetime and time is not the same as spacetime. But you can treat spacetime t the same as spacetime x y and z, you just use a different equation. Is this what you're saying?

Right so we just perceive them as different aspects of the same underlying thing (ie they 'resolve out' differently in experiance). What about this anaolgy: 2D flatland vs the 3D world where the z axis (or y if you take y to be up) would seem very different to a flatlander to the x and y...

That's cleared up my one question thanks (I also looked on wikipedia in the mean time and saw some of the maths that shows SR treating the 4 coordinates the same (0,0,0,0).

I don't yet have the maths under my belt to understand completely what you mean by some of the terms in the above. Can I get this point clarified though, it might help me: are the four dimensions of spacetime similar to each other mathematically? What I mean is, is it OK to think of them...

Hi In trying to get to grips with SR/GR (I'm still unsure about what differentiates them!) one of the things that springs to mind is what it means for the nature of time. I've always thought (not too hard, just as a natural consequence of everyday experiance) that time is some fundamental...