Total Posts:100|Showing Posts:1-30|Last Page
Jump to topic:

Is kinetic energy faster than light?

Internet
Posts: 59
Add as Friend
Challenge to a Debate
Send a Message
6/16/2016 5:04:58 PM
Posted: 5 months ago
Lets say I have a 2 light year long metal pole. On one end is me, the other end has an alien holding it. If I pushed my end away from me, would the alien instantly feel the push?
Greyparrot
Posts: 14,268
Add as Friend
Challenge to a Debate
Send a Message
6/16/2016 5:07:11 PM
Posted: 5 months ago
At 6/16/2016 5:04:58 PM, Internet wrote:
Lets say I have a 2 light year long metal pole. On one end is me, the other end has an alien holding it. If I pushed my end away from me, would the alien instantly feel the push?

It would take a lot longer because there are spaces between the atoms of the material of your pole.
Internet
Posts: 59
Add as Friend
Challenge to a Debate
Send a Message
6/16/2016 5:13:49 PM
Posted: 5 months ago
At 6/16/2016 5:07:11 PM, Greyparrot wrote:
At 6/16/2016 5:04:58 PM, Internet wrote:
Lets say I have a 2 light year long metal pole. On one end is me, the other end has an alien holding it. If I pushed my end away from me, would the alien instantly feel the push?

It would take a lot lhonger because there are spaces between the atoms of the material of your pole.

But arent the atoms already compressed enough to the point my strength couldnt compress them anymore? If I pushed this poll 3 miles in a second, will this pole actually shrink 3 miles in size untill it reaches the alien?
Greyparrot
Posts: 14,268
Add as Friend
Challenge to a Debate
Send a Message
6/16/2016 5:14:40 PM
Posted: 5 months ago
At 6/16/2016 5:13:49 PM, Internet wrote:
At 6/16/2016 5:07:11 PM, Greyparrot wrote:
At 6/16/2016 5:04:58 PM, Internet wrote:
Lets say I have a 2 light year long metal pole. On one end is me, the other end has an alien holding it. If I pushed my end away from me, would the alien instantly feel the push?

It would take a lot lhonger because there are spaces between the atoms of the material of your pole.

But arent the atoms already compressed enough to the point my strength couldnt compress them anymore? If I pushed this poll 3 miles in a second, will this pole actually shrink 3 miles in size untill it reaches the alien?

it's like pushing a spring.
Floid
Posts: 751
Add as Friend
Challenge to a Debate
Send a Message
6/16/2016 5:15:14 PM
Posted: 5 months ago
No, what you are doing in reality is adding a force to the stick which causes a wave of compression to flow through it: the atom you touch moves closer to the atom next to it until the electromagnetic repulsion from the atoms is greater than the force you applied which causes the second atom to move away from that atom you touched. Repeat this all the way down the pole. This process is slower than the speed of light, so it would take some time longer than 2 years for the other end of the pole to move.
Internet
Posts: 59
Add as Friend
Challenge to a Debate
Send a Message
6/16/2016 5:26:46 PM
Posted: 5 months ago
At 6/16/2016 5:15:14 PM, Floid wrote:
No, what you are doing in reality is adding a force to the stick which causes a wave of compression to flow through it: the atom you touch moves closer to the atom next to it until the electromagnetic repulsion from the atoms is greater than the force you applied which causes the second atom to move away from that atom you touched. Repeat this all the way down the pole. This process is slower than the speed of light, so it would take some time longer than 2 years for the other end of the pole to move.

Could that mean a more dense pole (atoms packed tighter together) would transfer the force faster? Im kinda hung up on the idea that I personally would have enough strength to compress an already dense metal pole further.
v3nesl
Posts: 4,481
Add as Friend
Challenge to a Debate
Send a Message
6/16/2016 6:04:24 PM
Posted: 5 months ago
At 6/16/2016 5:26:46 PM, Internet wrote:
At 6/16/2016 5:15:14 PM, Floid wrote:
No, what you are doing in reality is adding a force to the stick which causes a wave of compression to flow through it: the atom you touch moves closer to the atom next to it until the electromagnetic repulsion from the atoms is greater than the force you applied which causes the second atom to move away from that atom you touched. Repeat this all the way down the pole. This process is slower than the speed of light, so it would take some time longer than 2 years for the other end of the pole to move.

Could that mean a more dense pole (atoms packed tighter together) would transfer the force faster? Im kinda hung up on the idea that I personally would have enough strength to compress an already dense metal pole further.

Well, I don't know the answer, but a couple of thoughts: The speed your push will travel down the pole is the speed of sound, so that's where we need to look for equations. In a gas, I'm pretty sure compressing the gas will increase the speed of sound, but I'm not sure if that would translate to a solid. My guess is that there would be a subtle effect, but not a big one. And it might actually slow the wave down instead of speeding it up - kind of like moving through a crowd instead of skipping freely. Equation-wise, density actually slows sound. It makes some intuitive sense - a steel pole will conduct sound better than a lead one.
This space for rent.
keithprosser
Posts: 1,979
Add as Friend
Challenge to a Debate
Send a Message
6/16/2016 6:04:58 PM
Posted: 5 months ago
Essentially pushing one end of a pole causes a compression wave to travel along it, essentially at the speed of sound in that medium - loosely the speed of sound is related to the 'stiffness' of the material. The fastest speed of sound I know is in diamond at 12,000 m/s, a long way behind the speed of light. So even a pole made of diamond would fail miserably.

If you did get an infinitely stiff material then - ignoring relativistic effects - the compression wave would travel infinitely fast along it, but there is no such thing as an infinitely stiff material. Quite what relativistic effects would come into it if you did get a material that several million time stiffer than diamond I leave to other posters.#
Fkkize
Posts: 2,149
Add as Friend
Challenge to a Debate
Send a Message
6/16/2016 7:23:37 PM
Posted: 5 months ago
At 6/16/2016 5:26:46 PM, Internet wrote:
At 6/16/2016 5:15:14 PM, Floid wrote:
No, what you are doing in reality is adding a force to the stick which causes a wave of compression to flow through it: the atom you touch moves closer to the atom next to it until the electromagnetic repulsion from the atoms is greater than the force you applied which causes the second atom to move away from that atom you touched. Repeat this all the way down the pole. This process is slower than the speed of light, so it would take some time longer than 2 years for the other end of the pole to move.

Could that mean a more dense pole (atoms packed tighter together) would transfer the force faster? Im kinda hung up on the idea that I personally would have enough strength to compress an already dense metal pole further.

The speed of sound in a solid is given by c = sqrt(E/d) where E is the elasticity modulus and d is the density. As you can see, you would need a rod of extremely SMALL density and/or extremely high stiffness.
To give you some numbers, in air c = 331 m/s (at 273 K) and in Aluminium c = 5100 m/s
that's still 5 magnitudes smaller than what you would need. Perhaps there will be relativistic effects I am unaware of preventing it anyway.
: At 7/2/2016 3:05:07 PM, Rational_Thinker9119 wrote:
:
: space contradicts logic
Fkkize
Posts: 2,149
Add as Friend
Challenge to a Debate
Send a Message
6/16/2016 7:33:38 PM
Posted: 5 months ago
At 6/16/2016 6:04:58 PM, keithprosser wrote:
Essentially pushing one end of a pole causes a compression wave to travel along it, essentially at the speed of sound in that medium - loosely the speed of sound is related to the 'stiffness' of the material. The fastest speed of sound I know is in diamond at 12,000 m/s, a long way behind the speed of light. So even a pole made of diamond would fail miserably.

If you did get an infinitely stiff material then - ignoring relativistic effects - the compression wave would travel infinitely fast along it, but there is no such thing as an infinitely stiff material. Quite what relativistic effects would come into it if you did get a material that several million time stiffer than diamond I leave to other posters.#

I just found out that carbyne has a 40 times bigger elasticity modulus compared to that of diamond. It has a density of 3430 kg/m^3, though

So c= sqrt(10^9 N/m^2 /3430 kg/m^3) = 540 m/s

unfortunate
: At 7/2/2016 3:05:07 PM, Rational_Thinker9119 wrote:
:
: space contradicts logic
Fkkize
Posts: 2,149
Add as Friend
Challenge to a Debate
Send a Message
6/16/2016 8:11:06 PM
Posted: 5 months ago
At 6/16/2016 7:33:38 PM, Fkkize wrote:
At 6/16/2016 6:04:58 PM, keithprosser wrote:
Essentially pushing one end of a pole causes a compression wave to travel along it, essentially at the speed of sound in that medium - loosely the speed of sound is related to the 'stiffness' of the material. The fastest speed of sound I know is in diamond at 12,000 m/s, a long way behind the speed of light. So even a pole made of diamond would fail miserably.

If you did get an infinitely stiff material then - ignoring relativistic effects - the compression wave would travel infinitely fast along it, but there is no such thing as an infinitely stiff material. Quite what relativistic effects would come into it if you did get a material that several million time stiffer than diamond I leave to other posters.#

I just found out that carbyne has a 40 times bigger elasticity modulus compared to that of diamond. It has a density of 3430 kg/m^3, though

So c= sqrt(10^9 N/m^2 /3430 kg/m^3) = 540 m/s

unfortunate
Something seemed off about the numbers. I used the wrong elasticity modulus apparently.

c = sqrt(32.7*10^12 Pa/ 3430 kg/m^3) = 97640 m/s

that's still orders of magnitude from the speed of light. Also I doubt Newtonian mechanics was appropriate for this calculation, since we are talking about a chain of singular atoms.
: At 7/2/2016 3:05:07 PM, Rational_Thinker9119 wrote:
:
: space contradicts logic
Internet
Posts: 59
Add as Friend
Challenge to a Debate
Send a Message
6/16/2016 9:42:21 PM
Posted: 5 months ago
At 6/16/2016 7:33:38 PM, Fkkize wrote:
At 6/16/2016 6:04:58 PM, keithprosser wrote:
Essentially pushing one end of a pole causes a compression wave to travel along it, essentially at the speed of sound in that medium - loosely the speed of sound is related to the 'stiffness' of the material. The fastest speed of sound I know is in diamond at 12,000 m/s, a long way behind the speed of light. So even a pole made of diamond would fail miserably.

If you did get an infinitely stiff material then - ignoring relativistic effects - the compression wave would travel infinitely fast along it, but there is no such thing as an infinitely stiff material. Quite what relativistic effects would come into it if you did get a material that several million time stiffer than diamond I leave to other posters.#

I just found out that carbyne has a 40 times bigger elasticity modulus compared to that of diamond. It has a density of 3430 kg/m^3, though

So c= sqrt(10^9 N/m^2 /3430 kg/m^3) = 540 m/s

unfortunate

And i thought i so cleverly found a way around the speed limit.

Its intriguing though that if we were able to see both ends, and one end did push, the object would look shorter.
VelCrow
Posts: 1,273
Add as Friend
Challenge to a Debate
Send a Message
6/17/2016 12:51:06 AM
Posted: 5 months ago
see this is the type of post i like to see in the science forums. one where an actual discussion takes place without the need to insult anyone. now the question is, how long before religious fanatics invade it? lets enjoy the peace while we can :D
"Ah....So when god "Taught you" online, did he have a user name like "Darthmaulrules1337", and did he talk in all caps?" ~ Axonly

http://www.debate.org...
Evidence
Posts: 846
Add as Friend
Challenge to a Debate
Send a Message
6/17/2016 1:04:42 AM
Posted: 5 months ago
At 6/16/2016 5:04:58 PM, Internet wrote:
Lets say I have a 2 light year long metal pole. On one end is me, the other end has an alien holding it. If I pushed my end away from me, would the alien instantly feel the push? :

Get a light saber, since supposedly nothing travels faster than the speed of light, so pushing a 2 light year long light saber would be instantly felt by your alien.
There are a thousand hacking at the branches of evil
to one who is striking at the root. - Henry David Thoreau
slo1
Posts: 4,333
Add as Friend
Challenge to a Debate
Send a Message
6/17/2016 12:39:59 PM
Posted: 5 months ago
At 6/17/2016 1:04:42 AM, Evidence wrote:
At 6/16/2016 5:04:58 PM, Internet wrote:
Lets say I have a 2 light year long metal pole. On one end is me, the other end has an alien holding it. If I pushed my end away from me, would the alien instantly feel the push? :

Get a light saber, since supposedly nothing travels faster than the speed of light, so pushing a 2 light year long light saber would be instantly felt by your alien.

Why would you think it would be any different with a light sabre? You still have a compression wave that must travel 2 light years before the tip moves.
Greyparrot
Posts: 14,268
Add as Friend
Challenge to a Debate
Send a Message
6/17/2016 12:51:20 PM
Posted: 5 months ago
At 6/17/2016 12:51:06 AM, VelCrow wrote:
see this is the type of post i like to see in the science forums. one where an actual discussion takes place without the need to insult anyone. now the question is, how long before religious fanatics invade it? lets enjoy the peace while we can :D

God hates springs.
Fkkize
Posts: 2,149
Add as Friend
Challenge to a Debate
Send a Message
6/17/2016 1:09:24 PM
Posted: 5 months ago
At 6/17/2016 12:51:20 PM, Greyparrot wrote:
At 6/17/2016 12:51:06 AM, VelCrow wrote:
see this is the type of post i like to see in the science forums. one where an actual discussion takes place without the need to insult anyone. now the question is, how long before religious fanatics invade it? lets enjoy the peace while we can :D

God hates springs.

He also hates parrots.
n-word, c-word, f-word you
: At 7/2/2016 3:05:07 PM, Rational_Thinker9119 wrote:
:
: space contradicts logic
Greyparrot
Posts: 14,268
Add as Friend
Challenge to a Debate
Send a Message
6/17/2016 1:14:24 PM
Posted: 5 months ago
At 6/17/2016 1:09:24 PM, Fkkize wrote:
At 6/17/2016 12:51:20 PM, Greyparrot wrote:
At 6/17/2016 12:51:06 AM, VelCrow wrote:
see this is the type of post i like to see in the science forums. one where an actual discussion takes place without the need to insult anyone. now the question is, how long before religious fanatics invade it? lets enjoy the peace while we can :D

God hates springs.

He also hates parrots.
n-word, c-word, f-word you

+1
RoyLatham
Posts: 4,488
Add as Friend
Challenge to a Debate
Send a Message
6/19/2016 6:24:50 PM
Posted: 5 months ago
The answer in the thread is correct, the push travels at the speed of sound in the material. There is a related mistake used in a 9/11 Truther argument that the World Trade Center could not have collapsed as fast as it did, because the rate implies that the metal broke faster than the speed of sound. The error is that the "Scientists for Truth" used the speed of sound in air. They should have used the speed in steel, which is about 18 times faster.
Jry2001
Posts: 45
Add as Friend
Challenge to a Debate
Send a Message
6/19/2016 8:20:08 PM
Posted: 5 months ago
At 6/16/2016 5:04:58 PM, Internet wrote:
Lets say I have a 2 light year long metal pole. On one end is me, the other end has an alien holding it. If I pushed my end away from me, would the alien instantly feel the push?

No, because kinetic energy moves at the speed of sound--sound waves are, by definition, kinetic.
Jry2001
Posts: 45
Add as Friend
Challenge to a Debate
Send a Message
6/19/2016 8:21:03 PM
Posted: 5 months ago
At 6/16/2016 5:26:46 PM, Internet wrote:
At 6/16/2016 5:15:14 PM, Floid wrote:
No, what you are doing in reality is adding a force to the stick which causes a wave of compression to flow through it: the atom you touch moves closer to the atom next to it until the electromagnetic repulsion from the atoms is greater than the force you applied which causes the second atom to move away from that atom you touched. Repeat this all the way down the pole. This process is slower than the speed of light, so it would take some time longer than 2 years for the other end of the pole to move.

Could that mean a more dense pole (atoms packed tighter together) would transfer the force faster? Im kinda hung up on the idea that I personally would have enough strength to compress an already dense metal pole further.

Denser poles would transfer the force faster, just like how denser objects have a faster speed of sound? :~{
dee-em
Posts: 6,469
Add as Friend
Challenge to a Debate
Send a Message
6/20/2016 7:19:19 AM
Posted: 5 months ago
At 6/16/2016 5:13:49 PM, Internet wrote:
At 6/16/2016 5:07:11 PM, Greyparrot wrote:
At 6/16/2016 5:04:58 PM, Internet wrote:
Lets say I have a 2 light year long metal pole. On one end is me, the other end has an alien holding it. If I pushed my end away from me, would the alien instantly feel the push?

It would take a lot lhonger because there are spaces between the atoms of the material of your pole.

But arent the atoms already compressed enough to the point my strength couldnt compress them anymore? If I pushed this poll 3 miles in a second, will this pole actually shrink 3 miles in size untill it reaches the alien?

I think that in practical terms you would not be able to achieve a 3 mile/second speed in one second on the metal pole. Too much inertia to overcome. The pole would bend or break if you applied too much force too quickly.
Floid
Posts: 751
Add as Friend
Challenge to a Debate
Send a Message
6/20/2016 12:51:11 PM
Posted: 5 months ago
At 6/16/2016 5:26:46 PM, Internet wrote:
Could that mean a more dense pole (atoms packed tighter together) would transfer the force faster? Im kinda hung up on the idea that I personally would have enough strength to compress an already dense metal pole further.

Yes, a more dense pole will transfer the force faster. If the rate of force transfer is not equal to the speed of sounds in a material I would imagine it is at least proportional and the speed of sounds increases with density of a material.
KthulhuHimself
Posts: 995
Add as Friend
Challenge to a Debate
Send a Message
6/20/2016 4:36:42 PM
Posted: 5 months ago
At 6/16/2016 5:04:58 PM, Internet wrote:
Lets say I have a 2 light year long metal pole. On one end is me, the other end has an alien holding it. If I pushed my end away from me, would the alien instantly feel the push?

Nope; because the interactions within the metal pole are entirely dependent on electromagnetic interactions between the atoms therein, which are limited to the speed of light; and so the alien would feel the push only after 2 years (well, more than just 2 years, but not in an instant anyways).
Fkkize
Posts: 2,149
Add as Friend
Challenge to a Debate
Send a Message
6/20/2016 6:17:08 PM
Posted: 5 months ago
It seems there is some confusion here. The higher the density, the LOWER speed of sound. A bodies density has little to do with its stiffness, which is what some seem to have equivocated.
: At 7/2/2016 3:05:07 PM, Rational_Thinker9119 wrote:
:
: space contradicts logic
Axonly
Posts: 1,802
Add as Friend
Challenge to a Debate
Send a Message
6/23/2016 12:32:19 PM
Posted: 5 months ago
At 6/17/2016 1:04:42 AM, Evidence wrote:
At 6/16/2016 5:04:58 PM, Internet wrote:
Lets say I have a 2 light year long metal pole. On one end is me, the other end has an alien holding it. If I pushed my end away from me, would the alien instantly feel the push? :

Get a light saber, since supposedly nothing travels faster than the speed of light, so pushing a 2 light year long light saber would be instantly felt by your alien.

Light sabers aren't real BTW
Meh!
Evidence
Posts: 846
Add as Friend
Challenge to a Debate
Send a Message
6/26/2016 1:33:46 AM
Posted: 5 months ago
At 6/17/2016 12:39:59 PM, slo1 wrote:
At 6/17/2016 1:04:42 AM, Evidence wrote:
At 6/16/2016 5:04:58 PM, Internet wrote:
Lets say I have a 2 light year long metal pole. On one end is me, the other end has an alien holding it. If I pushed my end away from me, would the alien instantly feel the push? :

Get a light saber, since supposedly nothing travels faster than the speed of light, so pushing a 2 light year long light saber would be instantly felt by your alien.

Why would you think it would be any different with a light sabre? You still have a compression wave that must travel 2 light years before the tip moves. :

Example:
You are traveling in your spaceship at 0.2C, passing the 'Happy Atheists' now living on Mars, they look up and detect your ship, .. you turn on your headlights.

Q. What "speed" are the Happy Atheists on Mars detecting the "light" from your headlights traveling at? They have a sensor that has detected not only your ship doing 2.0 C relative to them, but also the light as soon as you turned it on.

(Remember your speed is 0.2 C relative to Mars. You may use ALL relativistic effects on the ship, what effects this would have on the light coming from your ships headlight, .. also the relativistic effects on Mars caused by your ship passing them by, etc.
Leave no rock unturned. Oh yeas, please don't tell me this: "my ship would not have any relativistic effects on Mars including all the Happy Atheists living there, I studied relativity from lectures by famous Professors at well know Universities (YouTube), they all say two objects distancing from each other experience relativistic effects!)

Thanks.
There are a thousand hacking at the branches of evil
to one who is striking at the root. - Henry David Thoreau
Evidence
Posts: 846
Add as Friend
Challenge to a Debate
Send a Message
6/26/2016 1:39:03 AM
Posted: 5 months ago
At 6/23/2016 12:32:19 PM, Axonly wrote:
At 6/17/2016 1:04:42 AM, Evidence wrote:
At 6/16/2016 5:04:58 PM, Internet wrote:
Lets say I have a 2 light year long metal pole. On one end is me, the other end has an alien holding it. If I pushed my end away from me, would the alien instantly feel the push? :

Get a light saber, since supposedly nothing travels faster than the speed of light, so pushing a 2 light year long light saber would be instantly felt by your alien.

Light sabers aren't real BTW :

Lol, .. neither are "Big-Bangs in nothing", so just play along, use mathematics and the New Rules being created by the day by the gods/goddesses at 666CERN and the 6LHC temple. slo1 made a point, but I want to see if he can follow up on it?

God bless.
There are a thousand hacking at the branches of evil
to one who is striking at the root. - Henry David Thoreau
DanneJeRusse
Posts: 12,614
Add as Friend
Challenge to a Debate
Send a Message
6/26/2016 2:45:27 PM
Posted: 5 months ago
At 6/16/2016 5:04:58 PM, Internet wrote:
Lets say I have a 2 light year long metal pole. On one end is me, the other end has an alien holding it. If I pushed my end away from me, would the alien instantly feel the push?

The answer lies in phonons, you can read about them here and find a relevant equation to use:

https://en.wikipedia.org...
Marrying a 6 year old and waiting until she reaches puberty and maturity before having consensual sex is better than walking up to
a stranger in a bar and proceeding to have relations with no valid proof of the intent of the person. Muhammad wins. ~ Fatihah
If they don't want to be killed then they have to subdue to the Islamic laws. - Uncung
Without God, you are lower than sh!t. ~ SpiritandTruth
Evidence
Posts: 846
Add as Friend
Challenge to a Debate
Send a Message
6/27/2016 12:43:45 AM
Posted: 5 months ago
At 6/26/2016 1:33:46 AM, Evidence wrote:
At 6/17/2016 12:39:59 PM, slo1 wrote:
At 6/17/2016 1:04:42 AM, Evidence wrote:
At 6/16/2016 5:04:58 PM, Internet wrote:
Lets say I have a 2 light year long metal pole. On one end is me, the other end has an alien holding it. If I pushed my end away from me, would the alien instantly feel the push? :

Get a light saber, since supposedly nothing travels faster than the speed of light, so pushing a 2 light year long light saber would be instantly felt by your alien.

Why would you think it would be any different with a light sabre? You still have a compression wave that must travel 2 light years before the tip moves. :

Example:
You are traveling in your spaceship at 0.2C, passing the 'Happy Atheists' now living on Mars, they look up and detect your ship, .. you turn on your headlights.

Q. What "speed" are the Happy Atheists on Mars detecting the "light" from your headlights traveling at? They have a sensor that has detected not only your ship doing 2.0 C relative to them, but also the light as soon as you turned it on.

(Remember your speed is 0.2 C relative to Mars. You may use ALL relativistic effects on the ship, what effects this would have on the light coming from your ships headlight, .. also the relativistic effects on Mars caused by your ship passing them by, etc.
Leave no rock unturned. Oh yeas, please don't tell me this: "my ship would not have any relativistic effects on Mars including all the Happy Atheists living there, I studied relativity from lectures by famous Professors at well know Universities (YouTube), they all say two objects distancing from each other experience relativistic effects!)

Thanks. :

If the "speed of light" is a constant "C" or 186,282 m/p/s, then relative to me flying in my spaceship at 0.2 C then turning on my headlights the light is NOT a constant 186,282 m/p/s but is 0.8 C

Any objections?
There are a thousand hacking at the branches of evil
to one who is striking at the root. - Henry David Thoreau