'nothing, not even light'

[nokhor]

one of my greatest pet peeves is that whenever i read an astronomical article that invovles black holes they almost always have to use the stock phrase "nothing, not even light, can escape" its gravitational pull.

i don't understand, is it mandatory to use that phrase? do writers get penalized by their editors if they don't use it? is there a pro plagiarism commitee that enforces using the phrase? its never 'black holes, one way traffic' or 'black holes, what goes in doesn't come out'. its always "nothing, not even light" as if they hadn't reminded me, i might not have realized that light is something and not nothing. or when i think of 'nothing' i usually consider light one of its attributes.

[R'as al Ghul]

LOL.
I know what you mean. Isn't light generally considered to have no mass?
Not sure but this could be meant to emphasize the gravitational pull.
But I agree with you.
Didn't Stephen Hawking lately say that in fact there's a
remaining radiation emitting from the black holes? He revised his own theory
that nothing could escape. I think two jets of energy are propelled into space?

[nokhor]

yeah its called hawking radiation, but it's just that overused phrase that bugs me.

[Duke of Gloucester]

To escape the gravitational field of an object such as a planet or star, you need to be travelling at a certain minimum speed, or eacape velocity. IIRC the escape velocity at the surface of the earth is about 11 km/s. The escape velocity of a black hole is greater than the speed of light. Since nothing can move faster than light nothing can escape from a black hole.

According to the Theory of Relativity, light does have mass and is affected by gravitational fields. Light cannot escape from a black hole. It would actually be more accurate to say no electromagnetic radiation can escape. Hawking radiation is emitted from the space around a black hole.

[Ironside]

According to the Theory of Relativity, light does have mass and is affected by gravitational fields. Light cannot escape from a black hole. It would actually be more accurate to say no electromagnetic radiation can escape. Hawking radiation is emitted from the space around a black hole.

From what I know light doesn't have a mass but does act as it had one in several aspects. If light does have mass, then the Theory of Relativity says that this mass is unlimited and that would create a huge black hole that consumes the hole universe.

And IIRC Hawking radiation never really escapes the black hole. It's a radom creation of 2 particles on the exact edge of the black hole. One escapes and the other is getting drawn into the black hole. It also prevents the particles to destroy eachother as they usually do.

And I've found a source that didn't use 'nothing, not even light, can escape' in Swedish

[Ronin]

From what I know light doesn't have a mass but does act as it had one in several aspects. If light does have mass, then the Theory of Relativity says that this mass is unlimited and that would create a huge black hole that consumes the hole universe.

And IIRC Hawking radiation never really escapes the black hole. It's a radom creation of 2 particles on the exact edge of the black hole. One escapes and the other is getting drawn into the black hole. It also prevents the particles to destroy eachother as they usually do.

And I've found a source that didn't use 'nothing, not even light, can escape' in Swedish

I remember an old experient in physics class back in high-school that would prove that light has mass.....

it consisted of a glass container that was in a vacuum situation, in this container there was this device that kinda looked like a top, it was set in an axil that allowed it to spin, now...one of the sides of this thing was reflective, with the oposite side was black......when sun light shined on this device the little top thing inside spun around.....I can´t remember the name of the bloody thing in portuguese let alone in english...but if i can find a picture i´ll post it.

[Duke of Gloucester]

From what I know light doesn't have a mass but does act as it had one in several aspects. If light does have mass, then the Theory of Relativity says that this mass is unlimited and that would create a huge black hole that consumes the hole universe.

Light does have mass. The mass of a given photon is hf/c^2 where h is Plancks constant, c is the speed of light and f is the frequency of the photon. E=mc^2 tells us that mass and energy are basically the same thing, and since photons have energy, they must have mass.

The equipment Ronin describes is called a Crooke's radiometer, but in spite of what some school teachers tell you, it does not rotate because it is being knocked by photons. It rotates because the black sides are hotter than the silver sides. See the link:
http://www.physics.brown.edu/physics...emo/4d2010.htm

[The_Mark]

I remember an old experient in physics class back in high-school that would prove that light has mass.....

it consisted of a glass container that was in a vacuum situation, in this container there was this device that kinda looked like a top, it was set in an axil that allowed it to spin, now...one of the sides of this thing was reflective, with the oposite side was black......when sun light shined on this device the little top thing inside spun around.....I can´t remember the name of the bloody thing in portuguese let alone in english...but if i can find a picture i´ll post it.

It's a radiometer, but it doesn't prove that light has a mass. The experiment proves that the gas molecules inside (the thing doesn't contain a complete vacuum) take heat off the black side, expanding the gas on the black side of the squares, resulting in differences of pressure (pushing the black side a bit) and resulting in a flow of gas molecules around the little squares from the colder side to the warmer, giving the spinning thing more speed.

[Louis VI the Fat]

This is so very true!
And to make matters worse, it appears to be some form of global conspiracy:

Rien, pas même la lumière, ne peut s'échapper

You can't read about a black hole in French without the above phrase turning up. It translates word by word as: 'nothing, not even light, can escape'.

So who did invent this phrase anyway?

[English assassin]

Didn't Stephen Hawking lately say that in fact there's a
remaining radiation emitting from the black holes?

As the duke says its not from actually within the black hole. Quantum fluctuations produce pairs of virtual photons very close to the event horizon, one falls into the black hole leaving the other to carry on into real space as radiation "from" the black hole. He has recently published something more on it, something to do with a problem of infinite red shift or something. its all a bit beyond me.

Rien, pas même la lumière, ne peut s'échapper

I will now memorise this as a useful french phrase, and use it to appear enigmatic in France. It is a great step forward from Ou se trouve la gare?

So what ought to be replacing

[Beirut]

one of my greatest pet peeves is that whenever i read an astronomical article that invovles black holes they almost always have to use the stock phrase "nothing, not even light, can escape" its gravitational pull.

i don't understand, is it mandatory to use that phrase? do writers get penalized by their editors if they don't use it? is there a pro plagiarism commitee that enforces using the phrase? its never 'black holes, one way traffic' or 'black holes, what goes in doesn't come out'. its always "nothing, not even light" as if they hadn't reminded me, i might not have realized that light is something and not nothing. or when i think of 'nothing' i usually consider light one of its attributes.

I've had exactly the same thought for years!