E=MC2???? can we move at the speed of light???

Question

i had a thought if E=MC2 then Energy = Mass x Speedof light squared.

therefore if M(mass) = 0 then E = 0 x C2 which means E=0

therefore if some thing has energy than mass (M) must be greater than 0

therefore if light has energy it must have mass

so if light has mass and can move at the speed of light anything with mass can move at the speed of light.


i realise i may be mixing my science and mathematics to reach this solution but i would greatly appreciate if someone could explain where i have gone wrong

Answer 1

That's legitimate reasoning - except - the M in E=MC2 is rest mass, or more commonly noted as Mo.

Concerning light, its rest mass is a real quantity, not zero. If the light energy is converted to mass (M=E/C2), it would no longer travel at the speed of light simply because it would no longer be light.

The problem with an object with mass traveling at the speed of light is that the formula for kinetic energy becomes MC2 divided by, you guessed it, zero.

Proof: E=MC2 / [sqrt1-(V^2/C^2)]
If V^2 = C^2 (as in the velocity equaled the speed of light) the denominator becomes the sqrt of 1-1, or zero.

Answer 2

Well, a shorter answer would say that E=MC^2 is only half of the equation. This is the half that gives you the rest energy of an object. The full equation includes kinetic energy:

E^2=(mc^2)^2 + (pc)^2

Now, as an object with mass is accelerated, it's momentum increases much faster, and skipping all the math, basically it takes infinite energy to accelerate an object to the speed of light.

Conversely, the math also leads to the idea that any particle that doesn't have mass must then be traveling at the speed of light. So if a particle is traveling at the speed of light, it has no mass; if a particle has no mass, it travels at the speed of light. If a particle has mass, its speed is less than c; if a particle's speed is less than c, it has mass.

Answer 3

Light has zero rest-mass, which is why it is able to travel at the speed of light. The energy that it has is equivalent to a certain amount of mass (through E = M C squared) and the light photon has momentum that can be transferred to other objects. But the photon doesn't have 'mass' as we usually understand it. If it did, the mass would approach infinity as it tried to accelerate to the speed of light.

Q. Why did the tachyon cross the road?
A. Because it was on the other side.

Answer 4

Light has zero rest mass, of course it is never at rest. It has momentum, in fact the total pressure on the earth due to light from the sun is about 9 million pounds, that's integrated over 1/2 the entire face of the earth.

According to Einstein, nothing with zero rest mass can move at the speed of light. As you approach the speed of light, your mass increases, as your mass increases you need more and more energy to go faster. As you get to the speed of light your mass becomes infinite and you need infinite energy to reach this which is impossible....according to Einstein. A physicist I work with tells me though, that Einstein might not have had the whole picture.

Answer 5

It is possable to travel at the speed of light. The problem is, we dont have the technology for that kind speed. Fuel engines just wont do it. (turbine, Gas, jet.) Second the air would create such a friction (heat) that it would heat the mass past melting point. So that means you would burst in flames and die. So, IF we could get a different energy source and some type of protective shield (that was aerodynamic enough) We could reach the speed of light. So possable? Yes, in our life time? No

Answer 6

your not wrong. it just takes a LOT (trust me) of energy to get up to the speed of light. lets say that you have a 1kg object and you want to accelerate it to the speed of light. lets say you want it to take no more than a day. the speed of light is 299 792 458 m / s.
V (velocity or speed) = mass * acceleration

so you can tell were going to need a lot of acceleration. people however, can olny safely experience about 3 "g's", or 30 m/s^2. but over a long period of time, they can olny experience about 1g (10 m/s^2)

so say your accelerating at 10 m/s^2. how long would it take to reach light speed?

speed=acceleration*time
s/a=t
299792458/10=t
29979245.8s=t

thats about 8327 days, or 22.8 years. if you send an unmanned probe-thing, the problem would be the same, and even if it could go accelerate fast enough (say a day), you would need an immense amount of fuel, because you would have to be constantly accelerating for a long time (a day).

Comare the energy needed to get 1kg to go light speed:
Ke=1/2mv^2
ke=.5*1*299 792 458^2
ke=44937758940000000 joules

compare that to problably the fastest vehicle we have: X-15 rocket plane, traveling at mach 6.72 (6.72*speed of sound). lets say it olny weighs 1 kg too.

Ke=.5*1*340.29*6.72
ke=1143.3 joules

as you can see, it would be VERY hard to accelerate a space ship burdened with crew and other things to the speed of light

Answer 7

You have gone wrong at this point :

"so if light has mass and can move at the speed of light anything with mass can move at the speed of light."

How can you say that if any thing has mass then it should have speed of light ????

Einstein said that if you attain speed of light then your mass shall be converted into its equivalent energy according to the equation .

Answer 8

I believe that the speed of light is suppose to be a constant in the equation to define the amount of energy a object will have.

Answer 9

There is math in science so you can do that. This makes a lot of sense. But what is the mass of light? And can we really gain enough energy to pull that off? Makes sense, but i'm not that smart. There could be other things that you haven't factored in.

Answer 10

I can move at the speed of light