So how do objects gain mass at the speed of light in the first place?

Question

This question is based on the "Speed of light?" question that was asked some minutes ago. I would like to know if, say, there is an atom travelling at speed of light in a vacuum, how can it gain mass if everything around it is nothing but empty space? Does this mean that space can transform into matter? I'm confused!

p.s. Sorry if my question sounds kind of ignorant but I'm really interested in physics and am considering this field for college.

Mavs, I understand the concept but still don't get how is that possible... thanks.

Deep thought, sorry for giving thumbs down man but I thought you only wanted two points by placing an X for an answer. Thanks for the answer though.

Answer 1

The key thing to remember here (and it's not an easy concept) is that Mass and Energy are equivalent - somewhat like ice and water vapor - although completely different in physical appearance, they are none the less the same thing.

Energy, in Albert's famous equation, is rest energy. When we increase it's energy (by accelerating it, for instance, we may increase its kinetic energy in the old Newton sense, but in the new Einstein sense, we increase it's mass - remember, its equivalent - mass and energy are the same thing, only in a different configuration.
The space doesn't transform into matter, the energy required to accelerate the mass is added to the mass - you might say the energy is converted to mass (the opposite of nuclear fission, when the mass is converted to energy).

And lots and lots of energy is required to detect even a small increase in mass because a small amount of mass converts to a huge amount of energy - it is multiplied by light speed, squared!
Remember, E=MC2?
This phenomenon is no longer theory - it has been proved several times by acceleration of sub atomic particles - electrons, for instance, gain mass at close to the speed of light in exact proportion to Albert's equations.

Isn't physics great, eh?

Answer 2

Hi
The increase in mass is a mathematical construct that results from teh following relativistic equation:

M=M0/[(1-V^2/C^2)^(1/2)]

With M0 the rest mass, V the velocity, and C the speeed of light.

As one can see M goes to infinity if the [...] part on the right side of the equation goes to 0. Thus as one approaches V=C, the bottom becomes [(1-1)^(1/2)] which goes to 0.0, thus you get

M=M0/0.0 which is infinity.

If M goes to infinity then the force needed to inch the velocity faster (F=MA) also goes to infinity.

This is the basis of the statement that you can't go faster than the speed of light.

Hope this helps

Answer 3

Hello,
It does not mean that space can transform into matter.

All it means is that suppose you are holding a 1 kg ball and running. To you the ball, will always measure to be 1 kg, even if you are running close to the speed of light.
But to someone who is standing and watching you run, the ball ( and also you) will measure to be much heavier than 1 kg.

Answer 4

Particles with mass can only approach the speed of light.
Particles with no mass can only travel at the speed of light.

Any object will experience a tiny increase in mass as it accelerates. In essence, the object stores its kinetic energy in the form of increased mass according to Einstein's famous formula:

E = mc²

Where E is energy, m is mass, and c is the speed of light (defined as exactly 299,792,458 meters per second). The speed of light squared (c²) is equal to 89,875,517,873,681,764 m²/s².

The ratio of the object's relativistic mass (mr) to its rest mass (m0) is known as its Lorentz factor (γ). The Lorentz factor for a given speed (v) is given by the formula:

γ = mr/m0 = ( 1 – (v/c)² )^-0.5

For the speeds substantially less than the speed of light, the tiny increase in mass precisely matches the kinetic energy predicted by Newton's Laws of Motion. The Lorentz factor for an airliner traveling at 530 miles per hour (850 kilometers per hour) is just 1.0000000000003.

As the object's speed approaches the speed of light, the relativistic mass becomes significantly greater than rest mass. Relativistic mass inhibits all objects from attaining the speed of light. The table below shows the dramatic increase in Lorentz factor as the speed of an object approaches the speed of light.

Lorentz factor for a percentage of the speed of light

1% - 1.00005
10% - 1.00504
50% - 1.15470
90% - 2.29416
99% - 7.08881
99.9% - 22.3663
99.99% - 70.7124
99.999% - 223.607
99.9999% - 707.107
99.99999% - 2236.07
99.999999% - 7071.07