I need somebody knowledgeable in physics

So I have a little quandary that's been on my mind (on and off) for a good while now, hoping somebody can explain this.

Now as we all know, the speed of light is currently considered the "universal speed limit", the fastest matter or energy can travel. So we'll keep that in mind.

So, imagine that I have an iron bar (we'll just take away gravity for convenience) that's so long, it stretches from one end of the galaxy to the other. By this I mean the longest end to the other longest end, which if I remember correctly is 20,000 lightyears.

So here's this 20,000 LY long bar in space. Suppose I grab one end and push it to the side, it should make the other end move in unison like any other bar, right? But for that to happen, I'd have to apply energy at one end, and have a reaction from that energy occure at the other. This means that energy applied at one point can somehow travel to the other, 20,000X faster than the speed of light which should be impossible.

So how could this work? If no energy can travel faster than light, how does energy instantaneously travel 20,000 Light Years?

relativity my friend. time is not the same time on the other end of that pole. very good thinking tho, you are outside of the box which is the best way anyone can be.

i dont know how to explain it in detail but you would never be able to communicate that far instantaneously so i would be hard.

quantum physics seeks to explain however, how one subatomic particle after coming in contacts with another particle will communicate as though there was no distance in between no matter how far the distance really is.

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Originally Posted by anomalousirrelivance

relativity my friend. time is not the same time on the other end of that pole. very good thinking tho, you are outside of the box which is the best way anyone can be.

i dont know how to explain it in detail but you would never be able to communicate that far instantaneously so i would be hard.

quantum physics seeks to explain however, how one subatomic particle after coming in contacts with another particle will communicate as though there was no distance in between no matter how far the distance really is.

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I kind of see what you mean. Relativity and quantum theory have always interested me, but I'm sure my understanding is relatively (no pun intended) amateur.

But what you said reminds me of how my friend, a physics major, explained how electrical current doesn't actually travel. How there's already a current from one end of the wire to the other, and the "traveling charge" is just one charged particle energizing the next that's in contact with it. Actually that's probably a poor explanation, but I'm tired, stoned, and it's been quite a while since I last discussed this.

I really like your quantum theory on it though. I know we haven't gone into any detail yet, but I've been learning about how things are linked at the quantum level, how multiple particles from the same source, separated by thousands (or any amount) of miles, will be affected at the same time in the same way if just one of those particles is affected.
I think this is why a lot of buddhists (including myself) really like quantum theory, because it tends to jive with the buddhist theory that consciousness, while an impermanent set of multiple complex processes, has a certain "essence" to it, created by it, that at the smallest level is connected with all other consciousnesses, and can bind to other consciousnesses upon death (due to samsara-driven karma). Ah but I digress, gettin' high always makes me go off on tangents:D.

And please, by all means, anybody feel free to help me out with my super-long iron bar problem!

in a sense you are correct, this is pretty much what the super string theory is.

basically replace your iron bars with strings of gravity, and since ALL gravity effects ALL matter in the universe simultaneously, you could theoretically move a string and it will instantaneously move the part of the string billions of light years away.

at our current level of technology we dont have any way to manipulate gravity.

heres some more info on the theory, Superstring theory - Wikipedia, the free encyclopedia

i would also suggest reading "the elegant universe" but some chemistry and physics background will help alot

a theory about gravity, the one i choose to believe :)
"Gravity Dimension" - Gravity; faster than the speed of light!

hope this helps,
Raelum

Interesting topic, but it has been discussed in places that atoms can communicate with each other infinite distances with time not being a factor.

Well... about the problem of the iron bar:
When you push the bar, you are not pushing the bar as a whole. You are only actually pushing the atoms of it which are in contact with your hand. This atoms will then push their neighbors, their neighbors will push their own neighbors, and so...
The "pushing" that the atoms will do in their neighbor atoms travels trough the entire bar, like a wave, until its end. Look at the picture i did... the first line is the atoms of the bar, and in the second, 3rd, 4th, lines is what happens when you push it. Note that the end of the bar only moves in the last line, when the "pull" of the atoms reach there.
And the speed of this "pull" is not even the speed of the light, but the speed of the sound in that material. In case of iron, it some 3 miles/second.
The fact that the pull goes with the speed of the sound is very reasonable, if you remember that the sound is just the "pull" of the molecules in the air, and the sound actually is just a mechanical pertubation, a mechanical wave, through air, or steel , or whatever.
I hope my explanation is clear enough. If not, feel free to ask! :thumbsup:



EDIT: i cant resist to say that we really dont need to use quantum physics, relativity or strings theory to understand a wave travelling through a bar... its classical physics.

^^good reply, i was going to respond something similar to this but i think you covered it all quite nicely

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Originally Posted by 420ultimatesmokage

^^good reply, i was going to respond something similar to this but i think you covered it all quite nicely

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seconded

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Originally Posted by 420ultimatesmokage

^^good reply, i was going to respond something similar to this but i think you covered it all quite nicely

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Originally Posted by Raelum

seconded

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Thank you both! :thumbsup:
Anyway... im a physics teacher, so it was almost a duty to answer him...

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Originally Posted by Coelho

Thank you both! :thumbsup:
Anyway... im a physics teacher, so it was almost a duty to answer him...

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

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?

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.

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Originally Posted by 420ultimatesmokage

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

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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...

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Originally Posted by 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?

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Exactly.

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Originally Posted by Gandalf_The_Grey

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?

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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).

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 :(

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.

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Originally Posted by halfassedjediknight

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

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

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.

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Originally Posted by Coelho

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).

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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?:confused:

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Originally Posted by Gandalf_The_Grey

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?:confused:

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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.