/sci/ - Science & Math » Thread #9668322

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Anonymous Fri 13 Apr 01:20:33 2018 No.9668322 View Reply Original Report

Quoted By: >>9668330 >>9668370 >>9668478 >>9668483 >>9668760 >>9669568 >>9669644 >>9669748 >>9669753 >>9670242

Imagine a rope spanning a billion light years and a person at each end of the rope. Person A tugs on the rope in Morse code to send a message to Person B. Are they communicating faster than light?

Anonymous

Anonymous Fri 13 Apr 2018 01:22:59 No.9668330 Report

Quoted By: >>9668344

>>9668322

No, the movement of the atoms is sublight. The rope is not rigid so the information is not instantaneously transmitted across the distance.

Anonymous

Anonymous Fri 13 Apr 2018 01:26:44 No.9668338 Report

Quoted By: >>9668535 >>9668978 >>9670220

message only travels at the speed of sound of the material

Anonymous

Anonymous Fri 13 Apr 2018 01:29:37 No.9668344 Report

Quoted By: >>9668354

>>9668330
The rope is continuous so tugging on it results in instantaneous movement on the opposite end. Wouldn't the information travel faster than a beam of light across the distance?

Anonymous

Anonymous Fri 13 Apr 2018 01:34:27 No.9668354 Report

Quoted By: >>9668371

>>9668344

Rope is not continuous. Whatever gave you that idea? It is just an arrangement of atoms.

Anonymous

Anonymous Fri 13 Apr 2018 01:39:04 No.9668370 Report

Quoted By: >>9668373

>>9668322
tugs on the rope travel as waves along the rope. The speed of those waves is pretty slow desu. Try it out with a friend

Anonymous

Anonymous Fri 13 Apr 2018 01:39:23 No.9668371 Report

Quoted By: >>9668379 >>9668383 >>9668409 >>9668470 >>9669585

>>9668354
First, let's say it's not a rope, let's say it's a rod so that it's rigid and has no slack.

Are you saying if you have a continuous rod and you tug on it, the movement on the other end won't be instantaneous? How long would it take then?

Anonymous

Anonymous Fri 13 Apr 2018 01:40:25 No.9668373 Report

Quoted By: >>9668383 >>9668409

>>9668370
What if instead of a rope we assume a rod though? That is, an object with little to no slack.

Anonymous

Anonymous Fri 13 Apr 2018 01:42:50 No.9668379 Report

Quoted By:

>>9668371
F = ma mass = infinite anon for that rod requires force to move and with that force it will snap

Anonymous

Anonymous Fri 13 Apr 2018 01:44:29 No.9668383 Report

Quoted By: >>9668405

>>9668373
>>9668371
Christ, the same principle still applies
It's not about the slack in the rope
The force between the molecules is ultimately going to transfer at sub-light speeds as a sonic wave

Anonymous

Anonymous Fri 13 Apr 2018 01:50:37 No.9668405 Report

Quoted By: >>9668414

>>9668383
But what if it was made out of diamond?

Anonymous

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Anonymous Fri 13 Apr 2018 01:51:06 No.9668409 Report

Quoted By:

>>9668373
>>9668371

Anonymous

Anonymous Fri 13 Apr 2018 01:52:54 No.9668414 Report

Quoted By: >>9668426

>>9668405
On scales that large even the most rigid solids we know of might as well be fluids. You'd need something like what a neutron star is made out of, and that would just collapse under its own gravity.

Anonymous

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Anonymous Fri 13 Apr 2018 01:58:52 No.9668426 Report

Quoted By: >>9668461 >>9669352

>>9668414
What if it was made of EXOTIC MATTER that doesn't break?

Anonymous

Anonymous Fri 13 Apr 2018 02:19:41 No.9668461 Report

Quoted By:

>>9668426

Prove such matter exists and we'll entertain your hypothesis.

Anonymous

Anonymous Fri 13 Apr 2018 02:26:42 No.9668470 Report

Quoted By: >>9668472

>>9668371
Speed of sound in a media is how fast you can 'push' information through it. Take as an example a supersonic jet - you won't hear it until it passed you even though there is a continuous atmosphere between the two of you

Anonymous

Anonymous Fri 13 Apr 2018 02:29:03 No.9668472 Report

Quoted By: >>9668533 >>9668798 >>9670242

>>9668470

By that reasoning wouldn't no information be transmittable through a vacuum? Or it this a difference between light moving and molecules in the medium moving?

Anonymous

Anonymous Fri 13 Apr 2018 02:31:55 No.9668478 Report

Quoted By:

>>9668322
Ropes are elastic you fucking tard.

Anonymous

Anonymous Fri 13 Apr 2018 02:33:39 No.9668483 Report

Quoted By:

>>9668322
Is this picture taking place when driver is doing a 360 on the highway
>here hold my beer

Anonymous

Anonymous Fri 13 Apr 2018 03:06:55 No.9668533 Report

Quoted By:

>>9668472
The reason is as you stated. Mechanical waves like sound require matter to propagate through. Light does not

Anonymous

Anonymous Fri 13 Apr 2018 03:08:04 No.9668535 Report

Quoted By:

>>9668338
Underrated post.

Anonymous

Anonymous Fri 13 Apr 2018 05:13:46 No.9668760 Report

Quoted By:

>>9668322
no you fucking bad physics troll

The force yo put into the rope moves as phonons through the chemical bonds of the material. This is lower than the speed of light.

fuck you

Anonymous

Anonymous Fri 13 Apr 2018 05:41:47 No.9668798 Report

Quoted By:

>>9668472
>Or it this a difference between light moving and molecules in the medium moving?
Speaking of which, vacuum IS a medium (with intrinsic properties) AND light moves differently when not in vacuum.

Anonymous

Anonymous Fri 13 Apr 2018 05:54:18 No.9668817 Report

Quoted By: >>9668982 >>9670242

OP should understand that the individual atoms have a lot of space within them and between them.

Also that forces have to travel.

How does a partical communicate with another particle near it?

Via some wave, a wave that can not exceed speed of light.

Anonymous

Anonymous Fri 13 Apr 2018 08:46:12 No.9668978 Report

Quoted By:

>>9668338
This. It would take longer than using a flashlight to signal the Morse code.

Anonymous

Anonymous Fri 13 Apr 2018 08:48:17 No.9668980 Report

Quoted By: >>9669121

If you had an infinitely long penis, could you use it to have sex with chicks from the past?

Anonymous

Anonymous Fri 13 Apr 2018 08:48:57 No.9668982 Report

Quoted By:

>>9668817
Fuck just think about earthquakes for a second.
They occur because of movement in the tectonic plates, but the motion does not propagate instantly.

Anonymous

Anonymous Fri 13 Apr 2018 08:52:23 No.9668985 Report

Quoted By:

It would take ~1 quadrillion years for person B to receive a message, ignoring all other complications.

Anonymous

Anonymous Fri 13 Apr 2018 11:25:24 No.9669121 Report

Quoted By:

>>9668980
Fukken lost m8

Anonymous

Anonymous Fri 13 Apr 2018 22:04:24 No.9669352 Report

Quoted By:

>>9668426
I don't care if your fucking rod is made of Adamantium or Uru!
In a relativistic universe there are no "perfectly rigid" bodies.
Pushes and pulls are transmitted through objects at the speed of sound. For any genuine materials, that's a tiny fraction of lightspeed.

Atom A doesn't touch atom B, y'know. Rap your knuckles on the coffee table and your hand is stopped by the mutual repulsion of the electron clouds in hand and table.
Since that repulsion is electromagnetic it can only move at the speed of light.

4Chan was down most of the day.
I expect to see a wave of suicides reported in the papers tomorrow -- trolls who couldn't indulge in their hobby and have nothing else to do or think about!

Anonymous

Anonymous Sat 14 Apr 2018 00:59:52 No.9669464 Report

Quoted By: >>9669516

So if a star is 20 lightyears wide and galactic winds pushes it east 100 feet then it would take 20 lightyears for it to move? Yeah I dont think so

Anonymous

Anonymous Sat 14 Apr 2018 01:35:13 No.9669516 Report

Quoted By:

>>9669464
Checkmate atheists

Anonymous

Anonymous Sat 14 Apr 2018 02:06:10 No.9669568 Report

Quoted By: >>9669584

>>9668322
Morse code is electricity which is much much slower than light retard.

Anonymous

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Anonymous Sat 14 Apr 2018 02:17:53 No.9669584 Report

Quoted By:

>>9669568

Anonymous

Anonymous Sat 14 Apr 2018 02:18:01 No.9669585 Report

Quoted By: >>9669595

>>9668371
>Are you saying if you have a continuous rod and you tug on it, the movement on the other end won't be instantaneous?
Yes. It would take time to travel to the other end. A rod is not some magical device that can break the laws of physics.

Anonymous

Anonymous Sat 14 Apr 2018 02:25:21 No.9669595 Report

Quoted By: >>9669601 >>9669613

>>9669585
Imagine I was a giant. The dimensions of my body span many light years. Does that mean it takes billions of years for me to make a motion? I am struggling to understand this. I can understand the rod breaking from the force required to push or tug on it in the first place but I can't understand how it wouldn't move instantly or near instantly for Observer B.

Anonymous

Anonymous Sat 14 Apr 2018 02:34:57 No.9669601 Report

Quoted By: >>9669608

>>9669595
you push first slice of atoms in the rod
that slice pushes next slice
the speed at which one slice pushes the next slice is the speed of sound in that material (usually air hence speed of sound)
usually when you push something it looks instantaneous because the speed of sound in that material is so fast

Anonymous

Anonymous Sat 14 Apr 2018 02:36:40 No.9669604 Report

Quoted By:

the real question is what if we had an atom that was 1 billion light years in diameter
If you push it will it move instantaneously

Anonymous

Anonymous Sat 14 Apr 2018 02:39:39 No.9669608 Report

Quoted By: >>9669654

>>9669601
Okay so when you push the rod, what do you see? Do you see it moving from your end? But then the middle of it will be "flexing" for billions of years as the wave of the force travels through the material while the person on the other end doesn't see any change?

Anonymous

Anonymous Sat 14 Apr 2018 02:46:47 No.9669613 Report

Quoted By: >>9669625

>>9669595
Actually bigger people have measurably slower reaction times than smaller people.

Anonymous

Anonymous Sat 14 Apr 2018 02:56:12 No.9669625 Report

Quoted By: >>9669640

>>9669613
So a giant would take years to move?

Anonymous

Anonymous Sat 14 Apr 2018 03:05:40 No.9669640 Report

Quoted By:

>>9669625
Depending on how big they are, there is like an inverse square law for this type of thing. like how fleas are tiny and can jump many times their own body length.

Also just getting the signals down your nerves is what I was actually referencing.

Anonymous

Anonymous Sat 14 Apr 2018 03:09:02 No.9669644 Report

Quoted By:

>>9668322
>Imagine a rope spanning a billion light years
Ok, let's assume it's a medium sized rope that weighs 1 pound per meter.
That means that the entire rope weighs about 9,460,000,000,000,000,000,000,000 pounds, which is just a tad smaller than the mass of the Earth.
Even if the rope were a perfectly rigid body like you're imagining, good luck finding anything that can move that much mass fast enough for communication to be possible.

Anonymous

Anonymous Sat 14 Apr 2018 03:17:04 No.9669654 Report

Quoted By:

>>9669608
Yes, exactly.

https://youtu.be/7Ht5m2iwDys

Anonymous

Anonymous Sat 14 Apr 2018 04:07:04 No.9669726 Report

Quoted By: >>9669730

what if my dong is 100 billion LY long and u tug it do i still die of loneliness?

Anonymous

Anonymous Sat 14 Apr 2018 04:09:45 No.9669730 Report

Quoted By:

>>9669726
Yes. You will be long dead by the time your jizz comes out at the other end.

Anonymous

Anonymous Sat 14 Apr 2018 04:33:23 No.9669748 Report

Quoted By:

>>9668322
The rope would stretch under tension. Even a small percent strain would become significant over the length of a billion light years. There would be a time dependent deformation process that would serve to move the signal through the rope.

Anonymous

Anonymous Sat 14 Apr 2018 04:35:44 No.9669753 Report

Quoted By:

>>9668322
Ok go outside and find a big fucking pipe. Tug on it. Notice it doesn't move instantly. Now apply the same principal to a big fucking rope in space.

Anonymous

Anonymous Sat 14 Apr 2018 10:06:37 No.9670220 Report

Quoted By:

>>9668338
But that effectively means all objects can move only as fast as the speed of sound in that material, which is not true

Anonymous

Anonymous Sat 14 Apr 2018 10:17:48 No.9670242 Report

Quoted By:

>>9668472
>>9668817
>>9668322
light waves are not real
>>9668322
yes

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