OT:Tempted to get this book

[Aiken]

Probably you meant that there's possibility of slight difference between gravitational and inertial masses. IIRC it's based on the definition that full energy E = mc^2 + K + W, there K - kinetic energy, and W - potential energy in the gravitational field, so higher module of W (closer to gravitating mass) means lower E (and smaller mass), since W is negative.

He also repeatedly claims that the "twin paradox" and the atomic clock experiment relating to the effect of time dilation is logically faulty because movement is relative. However, in standard science, it is not movement that is responsible for the time dilation effect but acceleration.

Actually t'= t*sqrt(1-v^2/c^2). There's nothing about acceleration here. Accelerating frames are matter of special relativity. Also twin paradox can be solved in special relativity only (edit: sorry not special, but general relativity in both cases).

[AMF]

If you're looking for a book that deals with "science as a whole, in a new way" I would try A New Kind of Science
by Stephen Wolfram. Well respected, intriguing, cool.

See:

http://www.amazon.com/exec/obidos/tg...00720?v=glance

[Captain Kwok]

douglas said:
His analogies using people in place of various objects are flawed in that a person is a very complex and inefficient organism and is constantly expending energy in ways not strictly necessary to do work.

Actually, our bodies are incredibly efficient, especially when compared to any machine we've built.

[deccan]

aiken said:
Actually t'= t*sqrt(1-v^2/c^2). There's nothing about acceleration here. Accelerating frames are matter of special relativity. Also twin paradox can be solved in special relativity only (edit: sorry not special, but general relativity in both cases).

Ah yes, you are right. I was thinking about the wrong thing. Let me try again: the author's contention that the relativity of motion (which is true) makes time dilation logically suspect is wrong because of the symmetry of time dilation while the twin paradox effect is actually an example of non-symmetry.

[narf poit chez BOOM]

http://www.drunkduck.com/Number_85/?i=348721

Beleive me, that's very relavent.

[sachmo]

I was hoping this was a thread about Fitzpatrick's War.

[Kamog]

The author says, "As we all know, perpetual motion machines are impossible,..." and gives the example that if you drop an object dropped into a tunnel through the Earth it would oscillate back and forth endlessly, saying that this result violates the laws of physics.

It does not. Perpetual motion machines are, in fact, possible if all friction is eliminated. Dropping an object into a tunnel through the earth will oscillate endlessly if there were no air inside the tunnel to create friction. If there is some air in the tunnel, the object's energy would be gradually lost as heat and the oscillation would decay and eventually stop, as expected.

It does not require the expenditure of energy to hold an object still in one place! You don't need a constant energy source to keep a fridge magnet stuck to the fridge or have a heavy object resting on a table. The object doesn't move because all the forces on the object are in balance and cancel each other out.

A light beam shining through glass will slow down and it does speed up again once it exits the glass. Why does it speed up again when it exits the glass? That's a good question, and I don't know why. I'm very curious as to what the reason is. But I think the reason a block of glass will heat up when light is shined though it is because the glass is imperfect and not completely transparent. Part of the light is absorbed and turned to heat. So not all the light emerges from the other side.

Regarding the Twin Paradox Thought Experiment: Hmm, I never thought of that paradox! I would very much like to know how to resolve this paradox.

[Fyron]

Kamog said:
A light beam shining through glass will slow down and it does speed up again once it exits the glass. Why does it speed up again when it exits the glass? That's a good question, and I don't know why. I'm very curious as to what the reason is. But I think the reason a block of glass will heat up when light is shined though it is because the glass is imperfect and not completely transparent. Part of the light is absorbed and turned to heat. So not all the light emerges from the other side.

It doesn't actually slow down, it just refracts within the glass and appears distored...

[narf poit chez BOOM]

Excuse me, but if I push on a block of wood and you push on a block of wood and we both have equal strength, given your arguement, neither of us would be expending energy. However, I think in half an hour you would say otherwise, no mater how balanced the forces are.

[Fyron]

narf poit chez BOOM said:
Excuse me, but if I push on a block of wood and you push on a block of wood and we both have equal strength, given your arguement, neither of us would be expending energy. However, I think in half an hour you would say otherwise, no mater how balanced the forces are.

Erm... the difference is that the refridgerator expends 0 energy to hold the magnet in place. The point was that not _all_ stationary objects require energy to remain stationary. Certainly, you can waste energy on an object that doesn't move in the end, but that is not the same thing. When pushing a block that isn't moving, you are not transfering any energy to it. The force you apply is not enough to overcome the counterforces involved, so no work is done on the block. As a result, its energy does not change. You have used energy, but that is for an entirely different reason. It requires a constant source of energy to keep your muscles contracted.