Physics question

[Lavi]

My understanding of gravity is that something has to have a mass to be attracted by gravity, and photons have no mass which allows them to travel at the speed of light as they are light (i think). So my question is how do black holes suck in light?

Gravitational lensing occurs when light from 'behind' a massive object such as a ecliptical galaxy is bent around it.

See? Tis not just black holes that affect light. To whether a photon has mass or not:
http://math.ucr.edu/home/baez/physics/ParticleAndNuclear/photon_mass.html
I think I fried my brain with this. The simplest example that I can give that even if light has no mass it will act like a particle is the Double-Slit Experiment. It may have mass, but some theories depend on it being massless (Gauge Theory).

 

[cuddly_tomato]

So my question is how do black holes suck in light?

In science we normally go for the simplest explanation.

Black holes (or to use the technical term, "sand") is actually the effect of having grit on the telescope lens, probably as a result of the astronomer who was at the telescope previously not putting the lens cap on. Because this grit is on the lens, away from any sources of light, it appears as black to the person looking through the telescope at the bottom. This also has the effect of preventing the person looking through the telescope from seeing anything where the grit falls into his line of sight, thus giving the impression of "sucking in light".

Incidentally, I am a park ranger by profession so please feel free to reject my thesis on quantum singularities.

 

[HardRockSamurai]

1. We're still not sure if they can.
2. A black hole's gravitational pull is believed to be so strong, it can pretty much suck in anything, except for time (although it's theorized that it can bend time.)
3. Please use Google next time.

Gravity is the bending of time and space by the presence of matter. So can a black hole bend time? Yes but so does the toast you eat in the morning.

I obviously meant "in a more noticeable fashion." Yeah, anything with matter can bend time, even a piece of toast, but I doubt anything on earth, or anything I can eat for breakfast for that matter, can compare to the time distortion that a black hole would cause.

Well, unless the toast had some kind of celestial butter on it...

 

[grimsprice]

To the best of my understanding Black Holes are made of anti-matter which which completely annhilates all matter, thus being a region of nothing, not even light.

I'm afraid you're completely and utterly wrong.

As for light, it always travels in a straight line, assuming local spacetime is flat. However, around mass, spacetime is distorted, causing the straight line to become a curve, which is why light bends around heavy objects, such as stars.

The reason why black holes are black is different, however. Any object with a certain mass has an escape velocity. An object's escape velocity is how quickly you need to move off the object's surface to escape its gravity. For planet earth, for an example, the escape velocity is around 11 km/s.

Black holes have an escape velocity greater than the speed of light.

Hell yeah. 12 posts. On the internet thats pretty impressive. I suppose its a testament to the quality of Escapists.

You get a cookie.

Spoiler

 

[sms_117b]

My understanding of gravity is that something has to have a mass to be attracted by gravity, and photons have no mass which allows them to travel at the speed of light as they are light (i think). So my question is how do black holes suck in light?

http://hyperphysics.phy-astr.gsu.edu/hbase/HFrame.html <- that page, scroll down to gravity and the photon. It's a bit mathematical. Though, if wanted I can/might be able to come back with a more wordy answer.

To the best of my understanding Black Holes are made of anti-matter which which completely annhilates all matter, thus being a region of nothing, not even light.

And everything has mass unless it's a wave, not a particle such as a photon (in wave form it's simply light energy). It's just so incredibly small it's generally ignored.


Of course I may be wrong. I sucked at physics. I still find it interesting though. So pick one of those two, either they're particles and thus have mass to be affected by gravity or black holes are made of anti-matter.

Edit: I am WRONG! Stop correcting me damnit.

I feel your pain, I had 6 quotes complain I didn't know what I was talking about the other day!

 

[ModsDeleteThisAccountPlease]

My understanding of gravity is that something has to have a mass to be attracted by gravity, and photons have no mass which allows them to travel at the speed of light as they are light (i think). So my question is how do black holes suck in light?

Lights a wave and despite moving at a unreachable speed, still travels in space and is still limited by time. A black hole messes with both space and time, creating a sink hole if you will that nothing can escape. As you fall closer to the sink hole, the faster you fall, same here, as you come in closer, the orbit radius decreases and speed increases.

 

[008Zulu_v1legacy]

Black holes bend and stretch space-time to what is essentially its breaking point. Within the event horizon, as you get closer to the singularity time actually slows until it stops.

The human perception of time is based upon the speed of light, so it only effects our perception of time. There is no actual evidence that black holes are capable of stopping time.

 

[beddo]

Black holes bend and stretch space-time to what is essentially its breaking point. Within the event horizon, as you get closer to the singularity time actually slows until it stops.

The human perception of time is based upon the speed of light, so it only effects our perception of time. There is no actual evidence that black holes are capable of stopping time.

The perception of time is based on speed. As you fall in towards a singularity time will essentially come to a stop, it's just mathematics.

So the mathematics tells us with that as an observer falls into a black hole time will stop, though really we don't quite know what this means.

If we're talking about evidence then we're nowhere; by their nature we cannot observe black holes, merely their effects. We will likely never be able to prove these things as you cannot get anything out of a black hole that has passed the event horizon.

 

[Lukeje]

God, I would have thought the sheer amount of nerd per square meter around these parts would mean people who like and/or understand science... guess not.

Apart from the explanation with space bending around a large mass (and what's larger than a black hole, which is most definitely not anti-matter and even if it were, anti matter does not have negative mass!), photons do not have rest mass. That's the mass a body has when it's not moving.

You see, energy and mass are the same thing. When you're not moving, you just have mass, that is rest mass. When you start moving at speed s, you gain energy, that is kinetic energy. And since energy is the same as mass, that means that moving increases your mass (via energy).

So basically jogging makes you fatter.

Well, not really, don't sweat! Since when you stop you lose the kinetic energy, you go back to your rest mass. It's the same with photons, except their rest mass is zero. However, since they move at the speed of light, they actually have quite a bit of energy, which is equivalent to mass through the formula E = mc[sup]2[/sup].

You may just be wording it badly, but you seem to have misunderstood what is meant by the term ``rest mass''. Photons do have rest mass; it is the mass that the particle would have if all the energy were converted to mass. If the particle has stopped, then its mass is equal to its rest mass.

E=1/2m*v^2. since the maximum speed of a particle is 300,000,000ms^-1, if a photon has more energy than required, it goes to it's wass, so yeah. Photons can temporarily have mass, it's all quantum mechanics.

(The above statement is more than possible to be bullshit.)

Did you really just try to use classical mechanics to describe a quantum mechanical particle? Here's a hint; the equation you're looking for is
E = m[sub]o[/sub]c[sup]2[/sup].

Black holes bend and stretch space-time to what is essentially its breaking point. Within the event horizon, as you get closer to the singularity time actually slows until it stops.

The human perception of time is based upon the speed of light, so it only effects our perception of time. There is no actual evidence that black holes are capable of stopping time.

The perception of time is based on speed. As you fall in towards a singularity time will essentially come to a stop, it's just mathematics.

So the mathematics tells us with that as an observer falls into a black hole time will stop, though really we don't quite know what this means.

If we're talking about evidence then we're nowhere; by their nature we cannot observe black holes, merely their effects. We will likely never be able to prove these things as you cannot get anything out of a black hole that has passed the event horizon.

No, your perception of time falling into the black hole will remain unaffected (at least theoretically. It's not exactly experimentally verifiable). It will just appear to an outside observer that you have stopped.

 

[008Zulu_v1legacy]

Assuming of course your body can withstand the immense forces exerted on you.

If black holes could effect time then the effect would be universal, since we can measure the speed of light (of which time is based) around a black hole and compare to an unhindered movement we can tell from this they can't.

Our perception of time isn't the universal constant.

 

[008Zulu_v1legacy]

Assuming of course your body can withstand the immense forces exerted on you.

If black holes could effect time then the effect would be universal, since we can measure the speed of light (of which time is based) around a black hole and compare to an unhindered movement we can tell from this they can't.

Our perception of time isn't the universal constant.

 

[008Zulu_v1legacy]

damn page double posted on me

 

[Cargando]

Photons can either be a wave or a particle, the particles have mass, and so are attracted to the black hole. Simple.

 

[Trivun]

Wave-particle duality. Due to various things that I don't understand having only gotten a C at A-Level Physics, some things (like photons) are particles that have wave-like characteristics, or waves that have particle-like characteristics. So light, being made up of photons, has the characteristics of particles (which are matter) despite being a wave. So because it has matter-like characteristics, it is still affected by things like gravity, though only extremely strong gravitational forces. There are other reasons too but since I'm a mathematician, not a physicist, I don't know them at all.