Why cant we go the speed of light?

[blackhole123]

From my understanding it is impossible to go the speed of light because as you go faster you get more massive which takes more energy so it would take an infinite amount of evergy to go the speed of light. I also just learned that as you go faster you get shorter, but I don't know how this would happen if you are getting more massive. Can someone clear this up for me?

[swansont]

From my understanding it is impossible to go the speed of light because as you go faster you get more massive which takes more energy so it would take an infinite amount of evergy to go the speed of light. I also just learned that as you go faster you get shorter, but I don't know how this would happen if you are getting more massive. Can someone clear this up for me?

 

Getting shorter (thinner, actually) and more massive are what happens as seen by observers in other frames of reference (and depends on what definition of mass you use). You won't see that in your own frame. The equation for kinetic energy diverges as you approach c, which is a consequence of c being constant in all inertial frames of reference.

[blackhole123]

Ok that makes sense.

 

I have another question though. Why is the speed of light the barrier that we cant cross? Why is it that precise speed and not some other speed? Sure light goes that fast but what does that have to do with anything?

 

Thanks again.

[timo]

I have another question though. Why is the speed of light the barrier that we cant cross?

Not sure if it is the answer you were looking for: But if you add some kinetic energy to a massive object' date=' it will move faster as a result. However, its velocity will always be <c no matter how much kinetic energy it has.

 

Why is it that precise speed and not some other speed? Sure light goes that fast but what does that have to do with anything?

If you look at the velocity of a massless object as a function of the kinetic energy, the velocity will always equal c, regardless of the kinetic energy. Light particles (photons) are massless. The reason why light travels at c is not that there´s something special about light and electromagnetism but simply that photons are massless (admittedly you might see that as being something special, but I hope you see my point here).

[J.C.MacSwell]

Ok that makes sense.

 

I have another question though. Why is the speed of light the barrier that we cant cross? Why is it that precise speed and not some other speed? Sure light goes that fast but what does that have to do with anything?

 

Thanks again.

 

We have nothing with which to propel it faster.

 

If light went faster, say 1.1 c, then that would be the barrier we could only approach and that would be the point where inertia would approach infinite.

[5614]

I interpreted his last question differently. I thought he meant why is c = 299,792,458 m/s? Why not 200,000,000 m/s or 300,000,000 km/s?

 

The answer I would give to that would be; that is how the universe is.

[blackhole123]

thanks

[Rocket Man]

i've always been confused over this topic,

is the increase of intertia due to time dailation?

and what is the speed relative to?

[swansont]

i've always been confused over this topic' date='

is the increase of intertia due to time dailation?

and what is the speed relative to?[/quote']

 

The nonlinear relation of momentum with speed, time dilation and length contraction are all consequences of c being constant in all inertial frames. The speed is measured with respect to some observer's reference frame. In your own frame, your speed is zero, so you will observe no relativistic effects in that frame.

[Ferdinand]

I cannot logically get my head around the dilation of time, or that time elapses differently according to who is observing what. But in particular, how was Einstein, or anyone else, able to reason that time was not an absolute and now have it confirmed by experimentation?

I am still not enlightened about why - though I can regurgitate some of the explanations that I do not truly understand.

I apologise if this has been raised, discussed and answered previously. If so, could you please direct me to an enlightening repsonse to my ignorance?

 

Thanks.

 

Ferdinand

[woelen]

The key to understanding this is the concept of "Lorentz transformation". It is a transformation between two coordinate frames, which preserves the speed of light.

 

In Newtonian mechanics, we have something called Galilei transform. It relates coordinate frames of different observers, who are moving relative to each other. This transformation leads to addition of velocities as simple linear additions. E.g. you are moving with a velocity v1, and you fire an arrow, which moves with speed v2, relative to you. A fixed observer (whatever "fixed" may be), observes an arrow, moving with speed v1+v2.

 

In reality, however, velocities may not simply be added (or subtracted if they are in opposite direction). A more accurate description is that velocities are "added", using Einstein addition, instead of normal addition. So, instead of writing v1+v2, we must write v1┼v2, with ┼ being the Einstein addition.

 

The Einstein addition is as follows for velocities in the same direction:

 

v1 ┼ v2 = (v1 + v2)/(1 + v1*v2/c²), where c is the speed of light.

 

This has the following properties:

v1 ┼ c = c

c ┼ v2 = c

v1 ┼ v2 < v1 + v2

 

 

For v1, v2 much smaller than c, v1 ┼ v2 is VERY close to v1 + v2. That is why in daily life we never notice the properties of the Einstein addition of velocities. We are so much trained by our daily life experiences that velocities simply add up, that any deviation of that is totally alien to us. Even for the fastest rockets we have, v1 ┼ v2 still is very very close to v1 + v2.

 

The following link may be helpful for you:

 

http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/veltran.html

[RyanJ]

I cannot logically get my head around the dilation of time, or that time elapses differently according to who is observing what. But in particular, how was Einstein, or anyone else, able to reason that time was not an absolute and now have it confirmed by experimentation?

I am still not enlightened about why - though I can regurgitate some of the explanations that I do not truly understand.

I apologise if this has been raised, discussed and answered previously. If so, could you please direct me to an enlightening repsonse to my ignorance?

 

Thanks.

 

Ferdinand

 

I think of time dilation like this (not sure if its factually accurate, its only meant as a way of thinking about how it works for me).

 

I imagine the combination of velocity through space and time to have an ultimate maximum, the speed of light. When we are absolutely stationary we have no velocity through space and therefor must be expending all the "velocity" through time. However when we move through space some of the "velocity" through time is taken and transfered to space therefor time elapses are a slower rate (velocity) with increased speed.

 

As I said its not meant to be taken literally, just an example of a way I think explains the effects well.

 

-- Ryan Jones

[woelen]

Ryan, in fact your idea is not that strange at all. It can be expressed mathematically also.

 

The rate at which time elapses and the speed at which you move are related as follows:

 

c² = v² + c²*(dt/dt0)²

 

Here dt0 is the rate of flow of time for an object, which is at rest, relative to you, dt is the rate of flow of time for the object you observe, which has a velocity, equal to v. So, you see, that if v is increasing, then the rate of flow of time t must decrease. For v = 0, dt is equal to dt0 and time flows at maximum rate (the rate, we observe intuitively, and which intuitively is absolute). For v = c, dt is equal to 0.

 

This formula also shows that the maximum velocity, which can be achieved is c, otherwise we would need to introduce complex arithmatic, which has no physical meaning here.

[swansont]

v² - c²*(dt/dt0)² is the invariant quantity.

 

You can look at it as your velocity through spacetime. If the spatial term gets bigger, the time term has to get smaller.

[Ragib]

I cannot logically get my head around the dilation of time, or that time elapses differently according to who is observing what. But in particular, how was Einstein, or anyone else, able to reason that time was not an absolute and now have it confirmed by experimentation?

 

We'll you see, Eienstein Conjected through reasoning that the speed of light was constant, or, independant of the speed of the transmitter etc. To understand time dialation it does not matter if the speed of light is the universal speed limit, you just need to know that it is constant. Now, im not very good at explaining this and putting it into words but..Say you had a spaceship in space, going very fast, say 0.5c. Ok, well, at that speed, the length of the space ship seems to be less, from the reference of another, stationary observer. So say, the pilot sends a laser beam to the other end of the plane. Now, since the speed of light is constant, but they see the distance it travelled to be different, they will disagree of the time it took the travel the distance. Therefore, time has dialated.