Does speed of light also mean strength of light?

AI Thread Summary
The discussion explores the relationship between light and gravity, particularly in the context of black holes. It presents various concepts about how gravity interacts with light, including the idea that gravity can actively pull light in or passively wait for it to fall into a black hole. The conversation also questions whether the speed of light correlates with its strength and discusses the implications of slowing light down, as demonstrated by recent scientific experiments. Participants clarify that while gravity is a force that attracts masses, its effect on light is complex and influenced by the mass of the black hole. Ultimately, the discussion raises intriguing questions about whether gravity can capture light that has been slowed or stopped, and whether anything can overpower gravity itself.
ColonelTravis
Messages
5
Reaction score
0
Physics mega-novice (i.e. moron) here, so I'm probably not thinking correctly about these things. Just curious which item below is close to what's generally understood about light and black holes. Maybe none are nowhere near being close, I would not be surprised.

Concept #1
A gravitational field starts at the center of an object and then goes out farther and farther, eventually dissipating but not technically ending, correct? From what I understand, a black hole isn't like a bucket or vacuum cleaner or something. But does that necessarily mean it's 2D and not 3D? Haven't seen that description before. So I'm wondering if gravity is something of a predator - starts at the center of a black hole, bolts out to whatever distance the event horizon is, grabs the light and then brings it back in. This might be another way of saying gravity has two forces - one that goes out and one that comes back. If Mr. Newton heard this, I'm sure he'd want throw a bunch of rotten apples in my face.

Concept #2
Gravity just sits there like a spider, waiting for some poor slob photon to crash into the web. In this case gravity is (for a lack of a better description) passive, while gravity in the previous example is active.

Concept #3
Gravity warps light around a black hole so much that light can do nothing but orbit what's left of a crushed dead star. Except this act of orbiting is cloaked by gravity and you can't see it.

Concept #4
Gravity sucks equal amounts of light from all directions, except the light does not orbit - everything drains into a single point in the center.

In the first two items above, I'm envisioning light heading into a black hole in the shape of a funnel. But I don't understand how gravity can force light into one spot that way. Wouldn't gravity need to be an equal opportunity sucker, since it came from a collapsed star that (presumably) collapsed evenly like a leaking balloon? That's my thinking with the other two items.

Either way, does fast light equal strong light? Plenty things in the universe are strong yet slow, just like you've got stuff that's slow and weak. I understand light is light. You can't say it's like something else, because there is nothing else like it. But let's say light has been slowed down - like when the Harvard people dropped the speed down to 30-some mph not long ago. Would slow light enter a black hole with less resistance than normal speed light? Or does the speed of gravity, if it really puts its nose to the grindstone, beat light to the event horizon door no matter what?
 
Science news on Phys.org
I am no master of all things stringy and black holey and speed of lighty, but I'm pretty sure that the speed of light is constant through a certain medium and can't be changed unless the medium it is traveling through is changed. So in that regard, I'm not sure how the Harvard people dropped the speed of light to ~30mph?

In terms of gravity, I thought it was more along the lines of a force generated by a body due to that body's mass. Two masses attract each other due to the affect of their gravities. So, a black hole which (i think) has a very large mass has a strong gravitational field that attracts other bodies of mass and even photons of light with negligible mass.

I'd be interested to see what some more of our experienced members have to say, but I'm not sure they could abswer your questions directly as they seem very difficult to understand. I don't think that strong is a word you can use with light, no matter how fast it's going. Maybe energy is better word to use.
 
Only concept (1) strikes me as outright wrong, while the interpretations (2), (3), and (4) can all be supported by the details of Einstein's GR. Concept (2) is not exactly correct since, as you said, the gravitational interaction diminishes with distance but is not ever zero; therefore the black hole has been pulling the photon in all along, rather then just sitting there. Concept (3) is the way that I would describe the process of light entering a black hole as seen by someone outside the even horizon. Concept (4) is what an observer would see inside the event horizon.
 
I think my original post is convoluted, sorry. My ultimate question is what maximum gravity does to light, if that light has been slowed down before it gets there. But I wanted to make sure I know what the heck is going on with a black hole in the first place, so that's why I had those 4 concepts.

Scientists have been slowing the speed of light for a while. What I did not know before I posted my question is that the Harvard people have actually stopped it. And they did this 8 years ago, which shows you how in touch I am with all this.
http://www.hno.harvard.edu/gazette/2001/01.24/01-stoplight.html

So my one question remains: Is it easier for gravity to capture slow light? But now I've added a second part: Can you capture stopped light?

Let's say light is minding its own business, chugging along toward a black hole at 186,000 mps, then someone (like the Harvard people but a gazillion times more sophisticated with tech stuff) decide to stop that light at the event horizon. Is gravity strong enough to capture it? Or maybe the better question: forget the light, would gravity need to overcome whatever force stopped it? Or maybe the BETTER better question is: if gravity can overpower light, can anything ever overpower gravity?
 
Last edited by a moderator:
A neutrinos has tiny mass but it will still be influenced by gravity. Gravity is just universal. I think gravitational field itself escape BH and propagate fast, but I do not know its speed may slow near BH ?
 
Thread 'A quartet of epi-illumination methods'
Well, it took almost 20 years (!!!), but I finally obtained a set of epi-phase microscope objectives (Zeiss). The principles of epi-phase contrast is nearly identical to transillumination phase contrast, but the phase ring is a 1/8 wave retarder rather than a 1/4 wave retarder (because with epi-illumination, the light passes through the ring twice). This method was popular only for a very short period of time before epi-DIC (differential interference contrast) became widely available. So...
I am currently undertaking a research internship where I am modelling the heating of silicon wafers with a 515 nm femtosecond laser. In order to increase the absorption of the laser into the oxide layer on top of the wafer it was suggested we use gold nanoparticles. I was tasked with modelling the optical properties of a 5nm gold nanoparticle, in particular the absorption cross section, using COMSOL Multiphysics. My model seems to be getting correct values for the absorption coefficient and...

Similar threads

Replies
10
Views
2K
Replies
5
Views
6K
Replies
20
Views
2K
Replies
49
Views
5K
Replies
15
Views
2K
Replies
10
Views
3K
Back
Top