h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

The get out is an energy the builds more gravity making the mass increase it dencity

The get out is an energy the builds more gravity making the mass increase it dencity

Sorry, jag, I don't understand you.

White is all visible light frequencies reflected from an object hitting the back of the eye, therefore, if no frequencies are reflected which happens in/on/around a blackhole, then black is an accurate description.

But what is the true "colour" of an object ?

It all depends on what light frequencies are ultimately allowed to filter through to the eye, but then again, our eyes are attuned to recognise a certain band of frequencies (visible spectrum) and since some animals and insects can "see" beyond those human limitations, do they see colours differently.

But in the end, black is black and white is white, or is it ?

Gnomon the black hole was a star just like our sun it died and colapse in on its self meaning what was massif srunk down in size but still wieghed the same
now as a black hole it sucks in a nother star but it does not get bigger as you might expect but it dose put on wieght and it keeps on doing this {the heaver the oject the more gaverty} so the moreand biger things it can pull in

hope that helps

That's right, jag. A standard black hole is formed by the collapse of a star slightly bigger the sun, possibly 3 or 4 times the sun's mass.

But the black holes at the centres of galaxies are supermassive, meaning having a very, very large mass - perhaps one millions times the sun's mass. I'm not sure whether they're formed by stars collapsing - it seems unlikely. Is it possible they were formed by eddies in the Big Bang, and then the galaxies formed around them?

Black is black, but white is not always white.

OK! Here's a rambling re-take on what's so far...

Gnomon : Post 5 “And they are a hole in the sense that you can throw things into them, like a hole in your back garden. If I said you had a hole in your back lawn, you wouldn't assume it was into another dimension, would you? But people seem to think that black holes are gateways into a different dimension, which they aren't. “

They are you know. Unfortunately, if you go into a black hole, what they'll make you is 1 Dimentional.

Jag : Post 11 “A misnomer is some one said the speed of light is the maximum speed
if that is so how can light disapear into a black hole”

It doesn't. We can't see it, because it reaches the point where to escape it would have to be moving faster than light.

Jag : Postt 17 “If time stand s still then nothing would have been swallow becourse it would be frozzen it time so light would show up and never fade“

No, there are only so many photons in a given level of light. Once they're gone, you can no longer see what's there, until you add further photons. It takes photons to see anything. You see by photons given off by something interacting with your eye.

Jag : Post 25 “the black hole was a star just like our sun it died and colapse in on its self meaning what was massif srunk down in size but still wieghed the same
now as a black hole it sucks in a nother star but it does not get bigger as you might expect but it dose put on wieght and it keeps on doing this {the heaver the oject the more gaverty} so the moreand biger things it can pull in”

Sorry Jag, you're wrong here. When a black hole absorbs matter, it does get bigger. It's just that, as a black hole has such a super-density, any matter it gains is reduced to the same matter state, so even a star falling in will be a tiny increase in mass, and an even smaller increase in size.

Gnomon : Post 26 “A standard black hole is formed by the collapse of a star slightly bigger the sun, possibly 3 or 4 times the sun's mass.”

Really? I'd always been led to believe that anything up to about 25 solar masses would go the Nova / Supernova route, then collapse into a red/white dwarf, and only the proper big boys would ever complete the transition into black holes.

>>even a star falling in will be a tiny increase in mass

If the black hole has a mass 2 times that of the sun, then a star the size of the sun falling into it will increase its mass by 50%, not a tiny increase. The black hole's radius will increase slightly - I don't know the formula.

>>I'd always been led to believe that anything up to about 25 solar masses would go the Nova / Supernova route

According to the Wikipedia article on the Chandrekhar Limit, it is 8 solar masses. Bigger than 4, but not as big as 25. Stellar-scale (as opposed to supermassive) Black Holes are created by supernova explosions, when the original star is massive enough. If the core remaining after the explosion is greater than about 1.4 times the sun's mass, it will collapse into a black hole.

Deadangel: Really? I'd always been led to believe that anything up to about 25 solar masses would go the Nova / Supernova route, then collapse into a red/white dwarf, and only the proper big boys would ever complete the transition into black holes.

"collapse into a white dwarf"

Red dwarf stars are normal stars just a bit smaller in mass than the Sun.

On an astronomy programme the other night they were talking about a white dwarf which has a diamond the size of the Earth at its core I astronomy!

>>diamond the size of the Earth

Do I detect a note of wishful thinking?

It's yours! I give it to you! Happy New Year!

thank you Reumbentman! I'll remember you in my will!

Thanks for correcting the errors in my knowledge.

plain English the black hole the sphere you see is gravity
in the centre is a core so dense that it probably ways at one
atom = to our whole solar system having a guess Id say it became a black hole just after the big bang what we need to know is how fast its gravity field is growing or put it how big is the sphere getting
just think its the only place you can see gravity in the raw

Gravity is one of those invisible things: you can only see its effect.

People are like that too. You can't ever say you can see the real person, or at least when you do, you speak metaphorically.

Reumbentman yes here on earth
But out in space most of witch is black and to find a black hole
you have to look for gavity and to see gravity you find xray
that shows you the egde to the black hole and the blackis gavity in the raw in full view you can watch it swalow light

Galaxy babe
Nasa have said they have found a black hole near to the time of big bang and its size would have been 17"of our sun

>>and its size would have been 17"of our sun

17 inches ?
17 times the mass ?

17 times the mass of our sun is quite a small black hole. The one at the centre of our galaxy, Sagittarius A*, is 4 million times the mass of the Sun.

17 times the volume I expect is meant . . . yet it is hard to imagine the implication of a certain volume close to the big bang when the worth of volume was high (there was not so much of it before or during inflation).

Or 17 times the diameter?

the black hole it self