I need somebody knowledgeable in physics

[Gandalf_The_Grey]

Woohoo for classical physics then! But are you telling me then, Coelho, that if I push the end of the bar the other end won't move for something like a million years? And if so, how can you have the first (lets say) 100 lightyears of bar bent, and the rest of it still strait because the waves haven't reached it yet? Wouldn't this have to result in the iron bar bending a good deal at the mere push of my finger, or breaking altogether?

[Esoteric416]

Check out a book called "Faster than Light: Superluminal loopholes in physics"
By Nick Herbert.
There is an example of your iron bar idea only explained using a spotlight.

[Coelho]

glad to see a cool pot smokin physics teacher :jointsmile:

My students liked it a lot! They knew i did smoke (well i only teached while high...) and i even invited some of them to toke with me... but they declined... i think they became afraid when i said i would give them the strongest hash oil... sometimes i think they were only posers, not stoners...

Woohoo for classical physics then! But are you telling me then, Coelho, that if I push the end of the bar the other end won't move for something like a million years?

Exactly.

And if so, how can you have the first (lets say) 100 lightyears of bar bent, and the rest of it still strait because the waves haven't reached it yet? Wouldn't this have to result in the iron bar bending a good deal at the mere push of my finger, or breaking altogether?

Well... you could not push one end of the bar all the distance that you wished at once... remember that a bar that long would have an enormous mass, and so an enormous inertia. If you were pushing it, you only could push it VERY slowly... so, the wave of compression created by your push would be microscopical (as it actually is in hard materials like iron and so).

[jessem98]

im personally interested in quantum phsyics (einstein podolsky bridge) and wormholes. For anyone who hasn't read up on wormholes, it's essentially a shortcut through space, and does not move faster than light, but in theory you could travel thousands of light years in hours...

how interesting is that shit?!?

i do wish i had the mental capacity for advanced physics, but then again math is not my strong suit

[halfassedjediknight]

i hate quantum physics. bunch of mathematicians trying to make sense of stuff they have no idea about. it seems so futile.

hawking might as well type in greek, because i dont understand anything he tries to point out.

[Delta9 UK]

hawking might as well type in greek, because i dont understand anything he tries to point out.

Yet millions of other people found his books informative and accessible.....

[Staurm]

I calculated what an iron bar stretching across the galaxy from one end to the other would be recently. It turned out to be something of the order of the weight of the earth, which surprised me. I thought it would be a lot more. Gives you an idea of just how big and heavy the world is.

[Gandalf_The_Grey]

Well... you could not push one end of the bar all the distance that you wished at once... remember that a bar that long would have an enormous mass, and so an enormous inertia. If you were pushing it, you only could push it VERY slowly... so, the wave of compression created by your push would be microscopical (as it actually is in hard materials like iron and so).

Honestly this explanation hasn't really cleared it up for me. As I said in the original post, we're doing away with gravity just for convenience sake, hence discounting the object's mass. But even in keeping with gravity and mass, lets just say my finger was strong enough to move the bar a few inches in one quick push. Again the same problem, if it takes 20,000 years (minimum) for the force to reach one end of the bar to the other, how can one end be moving to the side and not the other? If an observer looked at the whole bar from afar, would he see a bar with a traveling bend moving through it like a wave? How could that even work?

[Coelho]

lets just say my finger was strong enough to move the bar a few inches in one quick push.

If an observer looked at the whole bar from afar, would he see a bar with a traveling bend moving through it like a wave? How could that even work?

Yes... if you give the bar a huge push with you superman's finger, it would bend the bar, and this bend would travel exactly like a wave, cause it is one. Mechanical pertubations are sound waves into the material. We only dont see this waves in the everyday world because they travel very fast (some 3 miles/sec in the iron), so when we push a bar, the wave travels almost instantly to the other side. But if you had a long, long bar of rubber, this effect would be more noticeable, as the speed of the sound in the rubber is very low, so you would see the wave traveling through it.