Thinking outside the box. Or ,how I learned to love the para

[SAMU]

The chicken or the egg? The paradox: Chickens must come from eggs and eggs must come from chickens is a cyclical system, a "box" that evaluated on it's own terms is a priori insoluable.

The empirical flaw that the term all eggs come from chickens is demonstrably incorrect by pointing to other eggs can eliminated by repostulating that all chickens eggs come from chickens then a priori the paradox. Unless the repostulate can be empiricaly proven to be incorrect. That proof required an understanding of evolution and data from palientology to establish. But it does not require a broad understanding of either to understand.

Another more interesting paradox is the time travel paradox. Specificly The Grandfather Paradox. If a man goes back in time and kills his grandfather how can he be born to go back and kill his grandfather?

This question placed in terms of the laws of thermodynamics could read like this. A pack of matches has a certain amount of energy stored in it. If you place the pack on a table today and pick it up tomorrow to return to today you can place the pack from tomorrow next to the pack from today and have two packs containing twice the energy of one pack. You will have violated the first law of thermodynamics by increasing the net energy level of the universe by one pack of matches. Thus the paradox. Or is it?

If tomorrow exists, then todays pack of matches exists in tomorrow. Bringing the matches to today violates no laws of thermodynaics because you have not increased anything only changed somthing's position. a priori if tomorrow exists. However tomorrow cannot be proven empiricly.

Another way to approach the question is to empiricly examine the postulate of thermodynamics itself.

The a prioi postulate is : In a closed system like the niether matter nor energy can be created or destroyed. Empirical tests of the postulate can only be conducted on finite systems from which there is always leakage. Therfore there is no way to test weather matter can be destroyed.

But what about created?

Steven Hawking cooked up the idea of Hawking Radiation.

The way it works is this: virtual particals, which are two particals of equal but opposite charge form ajacent to each other in empty space and immediatly anihilate each other thus maintaining the thermodynamic level of the universe.

Hawking speculated that two such particals forming on the swarthschild radius of a black hole, one just inside the radius and never to escape and the other just outside and able to escape. Thus on rare occations they are prevented from anihilating each other and thus adding to the net thermodynamic level of the universe. The one that escapes is called Hawking Radiation

The last I heard was that Hawking radiation had been discovered coming from several black holes.

SAMU

[James]

Another more interesting paradox is the time travel paradox. Specificly The Grandfather Paradox. If a man goes back in time and kills his grandfather how can he be born to go back and kill his grandfather?
Easy. Just go back and kill him after the man's father is born. The man still survives and the grandfather is killed.

The last I heard was that Hawking radiation had been discovered coming from several black holes.

Query: what kind of protection would we need from this radiation? /phpBB/images/smiles/icon_wink.gif /phpBB/images/smiles/icon_razz.gif /phpBB/images/smiles/icon_rolleyes.gif

[Silas]

This is more physics than astronomy...but I've always been partial to the "many worlds" view of time (and quantum weirdness) rather than to the "collapse of the wave function" (standard) interpretation. So...you don't go back in time to "your" past, but to an alternate past that is very close to yours. You murder your gaffer (which most of us would consider "bad form," but etiquette should not stand in the way of science.) The result: you've cause a new "split" in the constant stream of cosmoses (?) that are already splitting away every time any atom, anywhere, undergoes radioactive decay...

There is a variant of the "many worlds" idea that *does* apply to astronomy as well as physics, and that's the notion that, in our metacosmos, due to the "expansionary phase" of the Big Bang, there are numerous regions of space that are causally isolated. It *might be* -- we're guessing, okay? -- that the fundamental laws of physics are slightly different from region to region. We simply happen to exist in a region where the rules are just right -- the strong nuclear force is very nicely balanced! -- that atoms and stars and people can exist.

Take these two notions (I won't call them "theories!") together, and you get what I call "The Ultimate Anthropic Principle," which merely says, "You exist in the universe that was necessary for your existence to be possible." Just as one example, perhaps in 99% of all possible histories, the Cuban Missile Crisis led to a devastating nuclear exchange. But we wouldn't be alive in those worlds; instead, we're alive in the world(s) where that didn't happen...

One last absurd thought: this may be the answer to the absence of extra-terrestrial life: if the universe were "rich enough" in resources for other sapients to exist and to travel here, they would have, and we'd have been wiped out. Thus, they haven't...because they don't exist...because the laws of physics are *just* rich enough to allow us to exist and no-one else...

(cf. "All the Myriad Ways" by Larry Niven with "Rumfuddle" by Jack Vance...)

I'll go back to my cell now...

Silas

[ToSeek]

I could be wrong, but I don't think Hawking radiation has been detected yet. It primarily comes from black holes much smaller than any discovered so far. (The smaller the black hole, the more Hawking radiation it generates, at least relative to its mass.)

[SAMU]

To seek,

The idea of "virtual particles" is such that they can appear anywhere. The larger the Swarthschild radius the larger area of the limit of the radius the more chances that a particle will form at the limit of the radius so more Hawking radiation comes from larger black holes.

SAMU

[Donnie B.]

Dead wrong, SAMU.

Hawking radiation is inversely proportional to the Schwarzchild radius.

If you don't believe me, maybe you'll take Hawking's word for it:


A flow of negative energy into the black hole therefore reduces its mass. As the black hole loses mass, the area of its event horizon gets smaller, but this decrease in the entropy of the black hole is more than compensated for by the entropy of the emitted radiation, so the second law is never violated.

Moreover, the lower the mass of the black hole, the higher its temperature. So as the black hole loses mass, its temperature and rate of emission increase, so it loses mass more quickly.


"A Brief History of Time", Chapter 7 (A Black Hole Ain't So Black)

[jkmccrann]

Dead wrong, SAMU.

Hawking radiation is inversely proportional to the Schwarzchild radius.

If you don't believe me, maybe you'll take Hawking's word for it:

:
A flow of negative energy into the black hole therefore reduces its mass. As the black hole loses mass, the area of its event horizon gets smaller, but this decrease in the entropy of the black hole is more than compensated for by the entropy of the emitted radiation, so the second law is never violated.

Moreover, the lower the mass of the black hole, the higher its temperature. So as the black hole loses mass, its temperature and rate of emission increase, so it loses mass more quickly.


"A Brief History of Time", Chapter 7 (A Black Hole Ain't So Black)

So, the negative energy streaming into the black hole causes it to reduce in size and heat up at an ever-increasing rate? That sounds awfully unstable.

Where would the flow of negative energy be coming from? Passing stars in the wrong neighbourhood?