Warning: this is a maths blog!

Some time ago, light was discovered to be a wave/particle duality. Count Louis de Broglie wondered (as you do) if electrons could be part of a wave.

They could.

He derived an incredibly beautiful formula from his research:

The funny h is wavelength, the p is momentum and the normal h is Planck's constant which is 6.626068 x 10^-37

Light definitely has a wavelength so it must have momentum which means it must also have mass. But what is its mass?

To find momentum, we would have to divide Planck's constant by its wavelength. Light's wavelength is 0.5 x 10^-6 which means that it's momentum is:

1.3252136 x 10^-27 kgm/s.

Now, momentum is mass multiplied by speed. We want mass so we divide momentum by its speed. The speed of light is 300,000,000 m/s. Therefore its mass is

4.417378667 x 10^-36 kg.

Multiply by 1000 to get the mass in grammes.

Don't forget that this mass is still really small.

Now for explanations. The momentum it exerts only effects atoms in our body. It can't effect our entire bodies. So the momentum is transferred in the quantun scale.

As for the mass, it isn't technically mass in a conventional sense. Mass, in physics, is defined as the amount of 'stuff' in a substance which is basically your photons (light particles). A common misconception is that weight is mass. Weight is a force due to gravity. Light doesn't have this weight. But, gravity can still influence it.

Take a black hole for instance. In a mediocre gravitational strength, light is bent inwards slightly. As we increase the strength, light gets bent further inwards until it eventually is pulled into the centre of the black hole. This means light can't escape. Thus, black holes would appear black since light wouldn't reach an observer.

Some time ago, light was discovered to be a wave/particle duality. Count Louis de Broglie wondered (as you do) if electrons could be part of a wave.

They could.

He derived an incredibly beautiful formula from his research:

The funny h is wavelength, the p is momentum and the normal h is Planck's constant which is 6.626068 x 10^-37

Light definitely has a wavelength so it must have momentum which means it must also have mass. But what is its mass?

To find momentum, we would have to divide Planck's constant by its wavelength. Light's wavelength is 0.5 x 10^-6 which means that it's momentum is:

1.3252136 x 10^-27 kgm/s.

Now, momentum is mass multiplied by speed. We want mass so we divide momentum by its speed. The speed of light is 300,000,000 m/s. Therefore its mass is

4.417378667 x 10^-36 kg.

Multiply by 1000 to get the mass in grammes.

Don't forget that this mass is still really small.

Now for explanations. The momentum it exerts only effects atoms in our body. It can't effect our entire bodies. So the momentum is transferred in the quantun scale.

As for the mass, it isn't technically mass in a conventional sense. Mass, in physics, is defined as the amount of 'stuff' in a substance which is basically your photons (light particles). A common misconception is that weight is mass. Weight is a force due to gravity. Light doesn't have this weight. But, gravity can still influence it.

Take a black hole for instance. In a mediocre gravitational strength, light is bent inwards slightly. As we increase the strength, light gets bent further inwards until it eventually is pulled into the centre of the black hole. This means light can't escape. Thus, black holes would appear black since light wouldn't reach an observer.

GleeoK

31 Jan 2013 22:10

31 Jan 2013 22:10

Nice blog! I may hate Algebra itself, but I like Physics (theory), Astronomy and Cosmology. I have a troublesome relationship with equations although I love what they do for our lives and the awesome scientific findings :3

PinoyBest13

31 Jan 2013 05:12

31 Jan 2013 05:12

Watch VSauce. I think they explained something about this.

And yes, gravity DOES affect light.

And yes, gravity DOES affect light.

HullBreach

30 Jan 2013 17:54

30 Jan 2013 17:54

Gravity does effect light. Just look at the relative position of distant stars before and during a solar eclipse. They have a visual dilation because of the way Sol bends the light with its gravitational pull. That is the premise of Einstein's Theories of Relativity and was proven over 100 years ago.

It was a good blog, just factually incorrect in the closing..

It was a good blog, just factually incorrect in the closing..

jsa005

31 Jan 2013 11:46

In reply to HullBreach

31 Jan 2013 11:46

In reply to HullBreach

By the way, for those who don't know, Sol is the sun. XD

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