Dumb 'speed of light' question

[NYPinTA]

Ok, for some reason this just occured to me. Everyone knows that question: "If you are driving at the speed of light and you turn your headlights on what would happen?" And the answer is that the headlights would turn on and the light would shoot forward at the speed of light as if you were standing still. Right? Relativity and all that...
So, my dumb question is, does that then mean that that light coming from the headlights of that car now going twice the speed of light?
Thanks.
:)

[JrMissToughChick]

Yes this is a dumb question I don't think I could answer it if I tried

~JrMTC~

[Kurt_eh]

Not quite.

Things tend to get a tad hazy as one approaches the speed of light.

The light emmitted from your high beams would have the wavelength compressed relative to the initial velocity of your car.

Someone will have to search out the equations, but it's really no different than the slow analogy.

If you're traveling at velocity x, and turn on your headlamps, the velocity of the photons emitted from your lamps is c. Not c+x.

Therefore if your velocity is c, then the light from your headlamps is still c, not c*2.

[Kurt_eh]

Found it!

http://www.fnal.gov/pub/inquiring/more/light/light_page20.html

It's impossible:

Doppler Formula:
http://www.fnal.gov/pub/inquiring/more/light/images/doppler.gif

Where v=velocity c=speed of light

So if V(emitted)=c then:

V=0.99c*(Square root((1+c/c)/(1-c/c)))

The c's cancel out:

V=c*(Square root ((1+1)/(1-1))

Which is

V=c*(Square root (2/0))

And the math breaks down...

[kechara420]

lordie, now my head hurts!

[Sawyer's Miller]

When it comes to relativity, and trying to do thought experiments, I always like to refer to the Lorentz equations, particularly the variant which deals with inertial mass.

The Lorentz equations tell us that for an object of rest mass Mo, and inertial mass M, as velocity v, approaches c (the speed of light in a vacuum), the inertial mass M approaches infinity.

This means as V approaches C, you're going to need more and more and more power from that engine to accelarate towards c.

M = Mo/sqrt(1 - (v/c)^2)

You can see from the above equation that if v=c we are dividing Mo by 0, which is indeterminate.

Think of it this way - we know that Kinetic energy, the energy of movement is proportional to the square of an objects velocity.

Or

Ek = 1/2 * m * v^2

Ek : Kinetic Energy
m : mass
v : velocity

Now, if Einstein is right, and v must be less than c for objects of mass > 0, then if we keep putting energy in, where does it go?

m has to get bigger.

So it would be impossible to accelerate a car from 0 mph to c mph - unless the car had an engine which was infinitely powerful. So driving at the speed of light, cannot occur.

[Kurt_eh]

This is your brain:

:bounce:

This is your brain on physics:

:blob:

[stellar]

The answer to the question is as follows:

The universe will implode.

[blue]

As SM says, you can't go that fast and still have mass. Another thing that happens to mass when it gets close to the speed of light--it gets heavier and heavier and harder to accelerate further. If you were going at the speed of light, you wouldn't have headlights, you wouldn't be you as you know you. You would be light.

[atlantagirl]

Okay, who wants to break into a verse of "I sing the body electric" right now! :D

[atlantagirl]

Dang! Now I can't get it out of my head.

Come on everyone! Sing with me!!

I sing the body electric.
I celebrate the me yet to come.
I toast to my own reunion
when I become one with the sun!
I celebrate Venus
I celebrate Mars
and I burn with the fire
of ten million stars.
And in time,
and in time,
we will all
be
stars!!!


:D :D :D :D :D

We now return you to your regularly scheduled physics thread. ;)

[Kurt_eh]

:crazydanc :bluenana: :banana: :groove:

[SeasonOfDeath]

Originally posted by blue
If you were going at the speed of light, you wouldn't have headlights, you wouldn't be you as you know you. You would be light.

You are my sunshine, my only sunshine
You make me happy...
:sun:

[db11]

In my fact free opinion, I doubt your question can be answered, as it is likely putting the cart before the horse, so to speak. There is nothing in our understanding of physics that can explain how your car, or any object with mass, for that matter, can travel at the speed of light. Without that, I can't see how anyone could take that next step and try to explain how an object with mass can interact with its environment when travelling at the speed of light.