Science Forums

# Speed of Light (again...)

## Recommended Posts

Assumptions:

1) Light bends when it passes a field of gravity, e.g. a planet. Hence light has a mass?
2) Light cannot escape from a black hole because the gravity field of a black hole is so strong.

Question:

Now, let us say there is a “light-black hole” from which light can escape just barely.  Is the starting velocity of the escaping light slower than 300,000,000 m/s until it reaches open space and only after that it really starts to rock’n’roll?

##### Share on other sites
7 hours ago, Pseudoscientist said:

Assumptions:1) Light bends when it passes a field of gravity, e.g. a planet. Hence light has a mass?

No, light does not have mass but it does have energy. Light moves in a curved line near a large massive body because space itself is curved, but the light is moving locally at c.

Quote

2) Light cannot escape from a black hole because the gravity field of a black hole is so strong.

The very large gravity of the BH curves space so much it curves back in on itself. Light following this curvature is still moving locally at c but cannot escape from the event horizon of the BH.

Quote

Question:

Now, let us say there is a “light-black hole” from which light can escape just barely.  Is the starting velocity of the escaping light slower than 300,000,000 m/s until it reaches open space and only after that it really starts to rock’n’roll?

If the curvature of space allows a path for light to escape, it will escape moving at c.

##### Share on other sites

in my understanding, only atoms have mass. light is made up of quarks, which are mass-less.

light bends from a black hole because it is made up of particles.

light should be constant even near a black hole.

i'm no expert though so take this with a grain of salt.

##### Share on other sites

The massless elementary particle of light is the photon, not the quark.

A quark is an elementary particle of matter, and has mass.

“The Standard Model posits that elementary particles derive their masses from the Higgs mechanism, which is associated to the Higgs boson. It is hoped that further research into the reasons for the top quark's large mass of ~173 GeV/c2, almost the mass of a gold atom, might reveal more about the origin of the mass of quarks and other elementary particles”

##### Share on other sites

When you say that light has no mass, it  certainly has energy and, as you titled your  other thread, E= mc^2, so it really makes no difference.

## Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

×   Pasted as rich text.   Paste as plain text instead

Only 75 emoji are allowed.

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.