Question about the properties of light and black holes

Hi, ATS. Not sure if anyone can help me out with this but I thought I'd throw it out there. I woke up this morning with a thought in my head. If light is suppose to have 0 mass, then how is light captured by black holes? From my basic understanding of gravity, the larger the mass, the more gravity. Black holes are suppose to be so massively dense that they can pull light into them. But doesn't gravity only affect other masses? I would really appreciate if someone out there could explain, or at least point me in the right direction on this. Thanx!

a reply to: revswirl

Honestly, we know very little. Basically nothing. We don't even understand how our own brain works let alone the universe. Someone might come along with some decent ideas. The honest answer is- we don't know.

I'm no physicist, so I may be mistaken, but my understanding is that it's light's momentum that allows it to physically interact with normal matter, and thus be affected by gravity.

a reply to: revswirl

From what I've read, photons have zero "resting mass"; that is to say, when a photon is not moving, it has zero mass. Of course, photons are always in motion, so this is actually never the case. Photons have "relative mass" which can be calculated based on its momentum. This is apparently why they can be affected by black holes.

originally posted by: revswirl
Hi, ATS. Not sure if anyone can help me out with this but I thought I'd throw it out there. I woke up this morning with a thought in my head. If light is suppose to have 0 mass, then how is light captured by black holes? From my basic understanding of gravity, the larger the mass, the more gravity. Black holes are suppose to be so massively dense that they can pull light into them. But doesn't gravity only affect other masses? I would really appreciate if someone out there could explain, or at least point me in the right direction on this. Thanx!

No, gravity effects space time, which is the medium the light is travelling through.

Think of it like light is a car driving on the road, and the road is getting pulled backwards faster than the car is driving forward.

a reply to: scojak

the only problem is that photons don't exist.

There is no proof photons exists, if so please show me, i would love to see a photograph of a photon

a reply to: revswirl

This might help . Gravity doesn't affect other objects like you are thinking. Instead it affects space itself.

Try thinking about it like this. Imagine you are walking along a straight path. If that path is near something that is large the object starts to bend that path slightly towards it. The larger the object the more the path is bent toward the object.

Now you can choose to not follow the path but it takes a certain amount of energy to do that. The larger the object is that is bending the path the more energy it takes not to follow the path. As the path bends in towards the object causing the deviation it takes more and more energy to deviate from the path. With a back hole at a certain point along the path (the event horizon) absolutely nothing can deviate, not even light.

Now the weight of the object traveling along the path has no effect on the path that is being bent. This is why you can drop two objects of different weights from a building and they more or less hit the ground at the same time (air resistance is a small factor).

So objects affect space by bending it and other objects traveling through space interact with space itself and therefore are affected by gravity as the path they are traveling along is bent.

Its not a perfect analogy but it helps

Wave–particle duality is an ongoing conundrum in modern physics...

Think of water waves. When a wave encounters an obstacle, it goes around it and closes in behind it...

Is light a wave, or is light a flow of particles? Well, the bottom line is that it's neither one.

Light behaves as a wave, or as particles, depending on what we do with it, and what we try to observe.

Light is an "quantum vector field."

originally posted by: TheSorrow
a reply to: revswirl

Honestly, we know very little. Basically nothing. We don't even understand how our own brain works let alone the universe. Someone might come along with some decent ideas. The honest answer is- we don't know.

Yes we do know, it is called general relativity. Einstein predicted the exact amount light would be moved by mass, in the case of proving relativity, that mass was the sun.

And during an eclipse one of his biggest critics was the first to prove him right.

originally posted by: revswirl
Hi, ATS. Not sure if anyone can help me out with this but I thought I'd throw it out there. I woke up this morning with a thought in my head. If light is suppose to have 0 mass, then how is light captured by black holes? From my basic understanding of gravity, the larger the mass, the more gravity. Black holes are suppose to be so massively dense that they can pull light into them. But doesn't gravity only affect other masses? I would really appreciate if someone out there could explain, or at least point me in the right direction on this. Thanx!

That's known as a common misconception in physics, which is the first one in this video. Mass is not the only thing affected by gravity, energy is too, and light is a form of energy:

Common Physics Misconceptions

originally posted by: intergalactic fire
a reply to: scojak

the only problem is that photons don't exist.

There is no proof photons exists, if so please show me, i would love to see a photograph of a photon

I am probably going to do a thread on this story....but this is proof enough for me:

www.todayifoundout.com...

It wasn’t until Danish Astronomer, Ole Römer entered the fray that measurements of the speed of light got serious. In an experiment that made Galileo flashing lanterns on a hill look like a primary school science fair project, Römer determined that, lacking lasers and explosions, an experiment should always involve outer space. Thus, he based his observations on the movement of planets themselves, announcing his groundbreaking results on August 22, 1676.

Specifically, while studying one of Jupiter’s moons, Römer noticed that the time between eclipses would vary throughout the year (based on whether the Earth was moving towards Jupiter or away from it). Curious about this, Römer began taking careful notes about the time I0 (the moon he was observing) would come into view and how it correlated to the time it was usually expected. After a while, Römer noticed that as the Earth orbited the sun and in turn got further away from Jupiter, the time Io would come into view would lag behind the expected time written down in his notes. Römer (correctly) theorised that this was because the light reflected from Io wasn’t travelling instantaneously.

If light did not travel, then the above story would never happen. Incidentally, if you read the above link, it talks about one theory of light being that it originated in our eyes, or that it traveled instantly. The discovery that light had a speed was the first step in proving the existence of the photon.

Otherwise, what exactly would you call light? You can observe it, and it has a speed.

Thanx, everyone, for the great responses. I'll keep checking in on the thread throughout the day to see what else is posted. I love this kind of stuff but I've shied away from really looking into quantum physics because my math skills are pretty weak. But this is a great start for my research and I appreciate the answers.

originally posted by: intergalactic fire
a reply to: scojak

the only problem is that photons don't exist.

There is no proof photons exists, if so please show me, i would love to see a photograph of a photon

Yes they do, and we can release a single photon at a time in experiments.

For example the famous double slit experiment.
en.m.wikipedia.org...

originally posted by: revswirl
Thanx, everyone, for the great responses. I'll keep checking in on the thread throughout the day to see what else is posted. I love this kind of stuff but I've shied away from really looking into quantum physics because my math skills are pretty weak. But this is a great start for my research and I appreciate the answers.

Math is not required to understand physics.

Einstein thought it all out first, then proved it with math second.

a reply to: bigfatfurrytexan

The Dauphin tutor. Towering intellect. Thanks.

I also did not know he had a hand in versailles, or heard of the romer scale.

Any object with mass causes space-time to stretch towards it. It might be a teeny-tiny amount around a single atom, but by the time you get to the size of a planet like Earth, that's enough to cause acceleration of 9.8 meters/second. Then with a black hole the curvature is so high that light would have to travel billions of kilometers before it could get past (imagine a rubber sheet with something heavy in the middle, that forces it to be stretched vertically billions of miles).

But it's the volume of space-time that been warped or pulled inwards towards the large object. Photons simply travel along this "fabric" in what locally to them is a straight line. But since space-time has been stretched in places, what is a straight line to them, is actually a curve to us.

Here's an answer from Sophie Allan from the National Space Centre:

We have seen from observations of light coming from behind objects of high mass, that the light is ‘lensed’ by the gravitational field of massive objects. However, light itself has no mass, so how is it affected by the gravity of these objects?

The first point to make is that while photons (little packets of light energy) do not have mass, they do have momentum, and a change in momentum yields a force, so in actual fact light is able to physically interact with matter. However, the key to this question came when Einstein developed his theory of general relativity. Photons of light are not technically affected by large gravitational fields; instead space and time become distorted around incredibly massive objects and the light simply follows this distorted curvature of space.

Energy to matter conversion. (E=mc2)

Photons have mass.

Light is affected by gravity(as evidenced via gravitational lensing.

a reply to: revswirl

Wait a minute, i think black holes only exists, because certain equations do not work properly without them.

I think they are just as real, as their silly calculations.

...until i see one, pics or it did not happen.

As ocean waves move through a sea of water molecules, light waves move through a sea of electron particles. It is why light is a part of the electromagnetic force.

It is the mass of the electron that is causing the gravitational lensing in detecting black holes.