[TeveVikep]

Do black holes increase in size, as in grow bigger, when consuming matter? And in order for gravity to pull in something doesn't it need to have some sort of mass? So does that mean light has mass, although very small?

[FredderiK]

Do black holes increase in size, as in grow bigger, when consuming matter?

The "size" of a black hole is roughly marked by the radius of the event horizon, which is just the point in space where the escape velocity is equal to the speed of light. The actual black hole itself is thought to be a point-sized, i.e. it's a singularity. The radius of the event horizon is approximately proportional to the mass of the black hole, so if the mass doubles, so does the radius.

And in order for gravity to pull in something doesn't it need to have some sort of mass? Technically, no - general relativity describes gravity as being the curvature of spacetime (caused by something called the stress-energy tensor of a system), rather than a force caused by mass in the classical sense, so massless objects can still be affected by gravity as such objects take through space is curved.

So does that mean light has mass, although very small? Not as such - light does contribute to gravitational fields, and it is affected by them, so its often considered to have "gravitational mass"; however, its rest mass is zero.

[TeveVikep]

Not as such - light does contribute to gravitational fields, and it is affected by them, so its often considered to have "gravitational mass"; however, its rest mass is zero.

rest mass, as in stationary? I thought light cannot exist stationary, it just disappears or something.

Also thanks for your answer, I assumed a black hole did not get larger when it consumed mass. This makes me worry slightly (though not enough for me to really bother with it) about the LHC. If it does create a tiny black hole which does start to pull in some mass is it theoretically possible for it to become larger and pull in more mass till, well whenever?

Also I remember someone saying that in order to create a black hole you need massive amounts of energy, would the LHC even be able to produce that amount of energy from smashing particles together.

[StethyEntinic]

rest mass, as in stationary? I thought light cannot exist stationary, it just disappears or something.

Hence its rest mass is zero. If it comes to rest, it has zero mass, therefore it does not exist and "just disappears"

Also thanks for your answer, I assumed a black hole did not get larger when it consumed mass. This makes me worry slightly (though not enough for me to really bother with it) about the LHC. If it does create a tiny black hole which does start to pull in some mass is it theoretically possible for it to become larger and pull in more mass till, well whenever?

It is also theorized that the black holes will not be stable enough to last more than a few milliseconds.

Also I remember someone saying that in order to create a black hole you need massive amounts of energy, would the LHC even be able to produce that amount of energy from smashing particles together.

Well, if they think the LHC might be able to create black holes then I would have thought it does have enough energy. At least for tiny ones.

[opelonafqe]

This is a long-standing and very popular urban myth - the coriolis effect is far too small to make any difference on water flowing through a plug hole.

.

NOT TRUE. this dose infact happen

[dietpillxanaxaxx]

Even stone?

Heat and pressure would turn it molten in a heartbeat, and it would sink through the "lighter" outer layers of gas into the core of the black hole. So.. yeah.

[StethyEntinic]

Heat and pressure would turn it molten in a heartbeat, and it would sink through the "lighter" outer layers of gas into the core of the black hole. So.. yeah.

Man, black holes are powerful stuff! I thought maybe it will suck in small light things like pocket lint, or bellybutton fluff, or little bunny rabbits. But stone?! Not even my Dyson could do that! ...Well, maybe little ones.

[Zarekylin75]

NOT TRUE. this dose infact happen

http://en.wikipedia.org/wiki/Corioli...bs_and_toilets

[TeveVikep]

Hence its rest mass is zero. If it comes to rest, it has zero mass, therefore it does not exist and "just disappears"

Could this be how matter was created? I remember reading a book in my Sience class many years ago explaining the big bang theory. From my calculations the universe expanded so far so fast that from what I could calculate it's speed would have to of exceeded the speed of light many times over.

My teachers also said that the radiation caused by the Big bang was travelling so fast that it created (or turned into) mass or something like that. Is this how matter was created?

EDIT: Most toilets flush in only one direction, because the toilet water flows into the bowl at an angle. Strange, when I flush my toilet or any other toilet I flush it doesn't spin or twirl at all, it just splashes and forces everything through the pipe.

[JonnTEN]

The idea behind hawking radiation is that a particle and anti particle are created (lets not get into how) and that usually in a VERY VERY VERY short amount of time they recombine resulting in the total energy difference being 0.

Near the event horizon of a black hole one of these particles can be sucked into the hole while the other escapes. This means that a particle has been created out of nothing and the only source of energy for this would be the black hole so it reduces in mass/energy by one particle.

Its estimated a black hole the mass of our sun would take many times longer than the age of the universe to dissapate this way.

[tsamprasxx]

Its estimated a black hole the mass of our sun would take many times longer than the age of the universe to dissapate this way.

How is that freaking possible?

[FredderiK]

From my calculations the universe expanded so far so fast that from what I could calculate it's speed would have to of exceeded the speed of light many times over.

The rate of expansion of the universe greatly exceeded the speed of light during the very early stages, but no physical entity exceeded the speed.

My teachers also said that the radiation caused by the Big bang was travelling so fast that it created (or turned into) mass or something like that. Is this how matter was created? Not quite - matter, as we see it, exists because the temperature the universe is low enough to permit it to do so; in very early stages, the temperature was so extreme that all matter simply annihilated itself into the form of ultra-high energy photons. As the universe expanded, the temperature dropped and matter condensed, eventually, into the forms that we see today - remaining photons at that time is the microwave background radiation that fills all space.

[FredderiK]

How is that freaking possible?

It's perfectly possible but as Meaker was saying, it's just that the rate of mass emission is so slow that it would a number of years so large for all of the black hole's mass to be emitted, that you would need to wait for many times longer than the age of observable universe to see this entire process.

[JonnTEN]

If its how a black hole the mass of our sun would be possible it would normally not be, but a black hole can be any mass (maybe breaks down in very small cases) in a singularity. The thing that changes is the radius from the singularity to the event horison.

Rememer the event horison is not some physical thing, its the point where the escape velocity becomes the speed of light, where no information closer can escape.

Ejections are caused by matter traveling close to but not entering the event horison, they are sped up to decent percentages of C (the speed of light) and then thrown out. If at any point they had entered the event horizon it would have been swollowed.

[dietpillxanaxaxx]

Man, black holes are powerful stuff! I thought maybe it will suck in small light things like pocket lint, or bellybutton fluff, or little bunny rabbits. But stone?! Not even my Dyson could do that! ...Well, maybe little ones.

I sense sarcasm.

[easypokergonj]

Considering some posts made in Physics threads, I'm not sure he's not serious