Physics question for those interested

[giszmo]

So everywhere I go, physicists are saying that it is impossible to travel faster than the speed of light. Can anyone explain why this is?

 

[Mr.Cool]

and yet, if the sun were to suddenly explode the earth would immediately feel the loss of gravitational pull and would start to spin out of orbit.

this would happen immediately, some 8 minutes BEFORE we even noticed the sun disapeared.

so.. how does information (gravity) travel faster than the speed of light? i thought nothing could travel faster ?

hmm...

 

[VSMVDD]

So everywhere I go, physicists are saying that it is impossible to travel faster than the speed of light. Can anyone explain why this is?

the quantusphere

the quantum realm is everywhere all at once

there is no such thing as impossible to travel faster than ..... here

 

[vamanan]

So everywhere I go, physicists are saying that it is impossible to travel faster than the speed of light. Can anyone explain why this is?

It is due to einsteins theory of relativity. When we travel faster than the speed of light, many physical parameters become imaginary which is not possible in real world.

 

[phyzWiz]

Well.. that's because gravity is a force not a particle or wave.

 

[nonlinear]

According to Einstein's theory of relativity, the relaion m=mo/(1-v^2/c^2)^0.5 suggests that mass approaches infinity as velocity of the body approaches c, the speed of light. Since mass and energy are interconvertible, this implies that energy of the body becomes infinity as v approaches c. However, energy must be always conserved (that is why there is energy crisis!), this warrents energy cann't be infinity. Obviously, speed of material particle can be very close to c but can not be equal to c.

 

[zefreh]

Note that physic states that material can not travel more than light speed ,but for example in electromagnetic signal phase can travel with a speed wich is more than light speed.

 

[echo47]

In general relativity, gravity propagates at the speed of light, so it would take 8 minutes for us to feel the effect of a vanished sun. However, it's difficult to directly measure and confirm this theory. Here's a related discussion:
https://math.ucr.edu/home/baez/physics/Relativity/GR/grav_speed.html

 

[nonlinear]

Only the particles having zero rest mass (such as photon, graviton,etc,) can travel at the speed of light.

 

[abel51]

If you travel at speed of light you will be totally converted to energy.

 

[nanda_kishore]

Reply for the question of Mr. Cool.
About gravity travelling faster than light.


Hi,

Let me clearly explain two points first.

We call something a particle only if it has some mass. (Photon is a energy particle with zero mass as per Eienstein Physics of energy-matter interconvertibility.)

Gravity is a cause and effect phenomena. it is not a information or particle. earth is a rocky object that doesnt not have any intelligence to interpret information. for example, its like stone stays in our hand as long as we hold it. It is a cause that is acting against gravity. if we leave it it will fall down because there is nothing against gravity. this is effect.


A similar thing happens in the solar system or Universe. all the planets are there in the free space is because the huge gravitational force of Sun holding it. and why it is not falling into the sun... This is because the earth is revoving around the sun at a certain velocity countinously so as to not to fall in the sun. Its like sun pulling the earth into itself (F=mg) and earth trying to stop it by its centrifugal force (F=mrw^2). Combinimng this two, sun 's pull g will be compensated by rw^2.
that is g=rw^2.

It is like a plane will stay in the air as long as it is flying (moving). think of the case where all engines of the plane stops in the mid air, the planes suddenly drop down and crashes right !!! This is a similar phenomena..

If the sun/star explodes (supernova), the gravitational pull of the sun suddenly decreases (Explosion decreases density in the body, and density directly proportional to gravity, hence gravity decreases.), but at that time the earth countinously revolves around the sun with a certain velocity and in a particular orbit so as to compensate the sun's pull. the moment the suns gravity decreases, the centrifugal force generated to compensate suns's 'g' while earth revolves will have obviously more force than the present gravitational force and it dominates the suns gravity and pull off the earth out of its orbit (by shear difference in force). that is spilling out.

I hope I answered your question.

PS: According to the chandrasekhar's limit, the sun will never explode. It just shrinks in itself.

 

[alisha]

its due to einstein`s theory of relativity!!

 

[Kral]

giszmo,
echo47 is right. Gravity can be considered to be a wave or a particle (graviton). Either way, its effect can not travel faster than the speed of light.
Regards,
Kral

 

[lightning r fun]

for example, you can write a post on here, and almost instantly you can read it on the other side of the world.
same thing with phones.

 

[123jack]

Just to throw a spanner in the works - :twisted:

Einstein did not say it is impossible for an object to travel faster than light.
That oft repeated statement is incomplete.

What he DID say was.... go on take a look...

But it occurs to me that the limitation should also apply to information aswell
as mass. Surely gravity counts as information? Which brings up the subject of entanglement I guess.

... Anyone who says physics aint fun isn't paying attention ;-)

jack