Does God exist?

[Raoul Duke, Jr.]

Would it even be possible for a human being to experience time distortions? Or would that human being's perceptions be likewise distorted, thereby making any inconsistencies undetectable?

[Coyote]

Actually, time and entropy are two different concepts. Primordial conditions are still a matter of highly theoretical conjecture AFAIK, but all processes create entropy, and the processes in the early moments of the universe were probably no exception.

So, entropy is more related to energy than the passage of time, then? If so, I have really limited my understanding of entropy. I'd commented to a friend of mine not too long ago that time was a human invention, as in 'hours, minutes, and seconds' and they exist mostly as concepts we'd artificially measured as much as we decided what constitutes a 'yard' or 'meter'. Entropy didn't much factor into the discussion but in my mind I saw entropy as the actual way that nature passes through temporal periods (Gads, that sounds so Treknospeak)-- ie, a radioactive particle decays, or a dead animal decays, not in a frame of days or months but simply as it occurs, and this was my original thought on entropy...

Obviously there is more to it than that..?

Oh, yeah-- I was torturing my friend with the threat that we'd soon be switching over to 'metric time': 100 seconds to every minute, 100 minutes to the hour, etc... actually had him there... for a second....

[Durandal]

Now, if we cannot back-plot the universe's expansion to an initial point, what about the validity of the 'edge' of the universe? I see where the 'edge' of the universe is actually only the edge that we have been able to observe so far, which at this point is 13 billion years' worth (the 'Hubble limit', it was called, or something like that) and there may be further expanse that we have not been able to see yet (light travelling towards us at a slower, 'redshifted' rate due to the Doppler effect). With time distortion being in correlation with mass/density, would time be moving at a different rate at the 'edge' of the expanse? And presumably, the same could hold true for individual galaxies-- that if we were to travel closer to the center of our own galaxy, the denser gravity there would also cause time distortion (at least to our perceptions)?

There is no edge to the universe. That would imply a center. When you look at the universe on large enough scales, it is homogenenous, or it looks exactly the same everywhere you look.

You are correct that we have a certain limit to what we can observe. Simply take the speed of light (300,000km/sec) and divide it by the Hubble Constant (72km/sec/mpc), and you'll get the radius of our observable universe. Anything beyond that radius is expanding away from us faster than the speed of light, so the light will never reach us.

You have to remember that our perception is extremely limited. Time wouldn't seem like it was moving any faster or slower unless you had a clock. We experience a time distortion standing on Earth, and astronauts in orbit experience time more slowly -- that is, when they come back, they are actually younger.

Would it even be possible for a human being to experience time distortions? Or would that human being's perceptions be likewise distorted, thereby making any inconsistencies undetectable?

Unless you have a clock, you wouldn't notice anything. If you were in a frame where time was at one rate and you were observing a frame where time moved faster, anything in that frame would look like it was moving in fast motion to you. However, everything in your frame would look perfectly normal.

Oh, yeah-- I was torturing my friend with the threat that we'd soon be switching over to 'metric time': 100 seconds to every minute, 100 minutes to the hour, etc... actually had him there... for a second....

Christ, don't I wish. The current time system makes absolutely no sense at all. However, the reason we stick with it has to do with time zones. 360 degrees divides into 24 timezones evenly.

[Darth Wong]

Would it even be possible for a human being to experience time distortions? Or would that human being's perceptions be likewise distorted, thereby making any inconsistencies undetectable?

Astronauts experience time distortion. Their clocks are slightly off when they return to Earth. Not that they notice.

[Darth Wong]

So, entropy is more related to energy than the passage of time, then?

Correct. It tells us which direction things go in (ie- it helps us define which way time points for a given process), but entropy is basically useful energy lost to randomness.

Entropy didn't much factor into the discussion but in my mind I saw entropy as the actual way that nature passes through temporal periods (Gads, that sounds so Treknospeak)-- ie, a radioactive particle decays, or a dead animal decays, not in a frame of days or months but simply as it occurs, and this was my original thought on entropy...

Entropy is disordered energy. Everything you do produces a little bit of it, amd you can't re-order it once this has happened; you can only get the disordered shit out of your face. This works for a while, but sooner or later, you run out of useful energy, and disordered energy is all that's left. This is the "heat death of the universe" theory.

[Raoul Duke, Jr.]

Would it even be possible for a human being to experience time distortions? Or would that human being's perceptions be likewise distorted, thereby making any inconsistencies undetectable?

Astronauts experience time distortion. Their clocks are slightly off when they return to Earth. Not that they notice.

That's not precisely what I meant to ask. I was hinting at the "if everything was shrinking, including all forms of measurement" paradox. (Sorry, I don't know the shorthand for that one.) In short, how could those experiencing the distortion detect the distortion in the absence of an unaffected reference point? It's my assumption that they couldn't.

[Coyote]

Durandal, Darth Wong, thanks for the info. I'll read more before I go any further, since at this point I'll really only be able to parrot what I've read. But thanks for the patience (and not tagging me as a Village Idiot). One last question-- is an Astronomical Unit measured from Earth's center mass to the Sun's center mass? Or the surfaces (as much as "surface" can apply to the sun).

Thanks again!

[Nick]

Durandal, Darth Wong, thanks for the info. I'll read more before I go any further, since at this point I'll really only be able to parrot what I've read.

For the reading part. . . I just picked up Hawking's "A Brief History of Time", and, given the way you've handled this thread, I think you'd be able to grasp what he's talking about. Another weird one I picked up was Paul Davies' "How to Build A Time Machine", but I highly recommend understanding Hawking's book before even trying the Davies one!

For the only being able to parrot results part - well, I don't know a lot of the mathematics involved either, so I'm generally relying on the authority of the relevant scientists myself

But thanks for the patience (and not tagging me as a Village Idiot).

The day we start dishing out VI titles to people just because they find it difficult to grasp general relativity and quantum mechanics, is a day I get very concerned. . .

Handing out VI's to people who seriously and persistently claim they understand those theories, when it is clear they don't have the foggiest idea what they're talking about, on the other hand. . .

It's all in the attitude

One last question-- is an Astronomical Unit measured from Earth's center mass to the Sun's center mass? Or the surfaces (as much as "surface" can apply to the sun).

As far as I know, the AU is an approximation, anyway - Earth doesn't have a circular orbit so the the distance to the Sun changes slightly over the course of the year (IIRC, it is closest to the Sun during the southern hemisphere's summer - but don't quote me on that part).

So I think the answer to your question might be, 'Not really either'. However, orbital mechanics is generally interested in the centres of things, because once they are far enough apart, they can be approximated as point masses, with all of the mass present at the centre of the object, so if it is one or the other, it is going to be the centres.

[Durandal]

Durandal, Darth Wong, thanks for the info. I'll read more before I go any further, since at this point I'll really only be able to parrot what I've read. But thanks for the patience (and not tagging me as a Village Idiot). One last question-- is an Astronomical Unit measured from Earth's center mass to the Sun's center mass? Or the surfaces (as much as "surface" can apply to the sun).

An AU is an average. Since the Earth orbits the sun in an elliptical fashion, its distance from the sun is always changing.

To answer your question, though, it doesn't matter where the AU is measured from, really. The sheer distance separating the respective surfaces of the sun and earth is so large that factoring in another few thousand kilometers for Earth and a few hundred thousand for the sun won't really affect the number in any noticeable way.

This is basically why you'll hear that, in astronomy, the error is always in the exponent. :)

[Nick]

This is basically why you'll hear that, in astronomy, the error is always in the exponent.

Heh - half the time they don't bother with anything except the exponent, and just talk about the order of magnitude of things. As you say, most of the time, any error less than an order of magnitude is barely even worth mentioning

[Durandal]

Yup. Planck time is actually (some number greater than 5)E-42s, but we just say 1E-43 because we're lazy. :)