"Speed of Light"

[Dungeoneer]

This is why I ask these kinds of questions. Because I want to understand how it all works, not because I think I've found a flaw. When I see a "logical flaw" in physics, I figure I just need to have it explained more/better, not that I'm the first person to see the "flaw."

And I'm very thankful to have people here who are able and willing to take the time to explain things more and better (mo' betta) to me. I love science, but I'm only a layman, and many papers and books are written above my level. Having peers, like here, who can explain things to my level without making me feel like a complete moron is quite lovely.

Bullgrit

I'm in the same boat as you, man.

Have you ever read anything by Paul Davies? He's a physicist who write books that make arcane concepts fantastically accessible to laymen. I never really understood what relativity was about until I stumbled across his book "Other Worlds" a few years ago. Since then I've gobbled up anything I find by him. He has an amazing gift for explaining stuff: quantum mechanics, gravity waves, dark matter, unified field theory and even a bit of string theory (although even Davies admits that string theory is pretty much pure math). Also, he's not afraid to dabble in more speculative stuff like the possibility of alien life, whether we're all living in a computer simulation, and the ever-popular question of whether god exists (Davies is agnostic).

Personally, I wish I could understand a bit of the math, but mathematics really is its own language. When someone says "Here's the basic equation behind X..." and then there is a string of Greek characters, I feel a bit out of my depth.

 

[Umbran]

But, we don't actually observe the singularity. Isn't observation limited to up to (but not quite including) the event horizon?

Nothing escapes from the singularity out beyond the event horizon to the outside world, no.

From one point of view, that could be turned into an argument that the event horizon is the entire structure of the black hole. The history of particles which have fallen into the hole seem to be contained in the topology of the surface.

If scientists took "we can't see it, therefore it isn't there" as our clarion call, we'd never have discovered atoms...

Whether the singularity exists becomes a pragmatic choice: Thinking about black holes is a lot simpler if a particular interior structure is presumed, and, generally, scientists rather prefer to keep models as simple as possible.

Here's two things:

1) What math we have actually suggests the structure.

2) What you say is true holds for "vanilla" black holes. Once we start talking about holes that have angular momentum and electric charge, the space within gets far more complex and interesting. There's no reason for you to care about it unless you've fallen inside, of course....

A question that I've had about light transmission is whether we could model this as discrete events, with the only physical events being the emission and absorption, with the absorption delayed according to the intervening distance, much as we would do if running a discrete event simulator, and sort-of what is done when rendering a scene: We compute the paths that light will follow, and render only the final point reached by light.

On a quantum level, yes, when you're talking about the interaction of individual particles. Well, what we do is take the initial states of the particles, imagine they go into a box, calculate all the possible interactions within the box, and come up with a probability distribution for what comes out box. This is QM, it is all about probability distributions.

This fails when you want to talk about the action of a prism or lens, however, as the number of interactions that can occur when passing through a macroscopic chunk of material becomes too high to contemplate.

 

[Umbran]

Ok, I am kinda picking up on what you are saying, but what if there is a general, all encompassing, here-to-fore unmeasured or even searched for, gravitational force pulling on the photons that prevent the photons from going faster.

A terminal velocity is reached when a motive force (like gravity) is balanced against a drag (like air friction). You're positing a drag, when there's no motive force. The photon is not a rocket, with something pushing on it.

As for photons, I have to ask, that, is it because they are massless that allows them to be simultaneously created and at c at that same instant?

Yep. Massless particles are special.

 

[Umbran]

Morrus, I can't tell you how much I, as a physicist, appreciate that you understand this and wrote it in this thread. I (and many many physicists) deal with this kind of logic all the time, and it is sometimes very difficult to get people to understand that mathematics is required. It's the same thing with the new paper by Hawking that has been a big deal in the press recently. It's a nice idea (which is actually very similar in some ways to what other people have done), but it's right now impossible to evaluate because there is no math (though other people's similar ideas are fleshed out mathematically). Physics can only be properly understood with a grasp of the mathematics involved. That's why Newton had to invent (or co-invent) calculus to describe planetary motion. I think it's possible to get an idea of what's happening with an explanation in words, but a full understanding and the ability to do physics simply requires a lot of math.

Agreed.

Take the word "schadenfreude". It has no direct and simple translation into English. If we are literal, it comes out to, "harm-joy". You need a sentence of English to approximate it - It is the feeling of joy or pleasure when one sees another fail or suffer misfortune.

Now, take that same idea - that there's no direct translation - and apply it here. All the concepts are best described by math. We try to give you approximations in English, but they are at best translations, and we often lose something in that translation.

 

[Bullgrit]

A camera that films at the speed of light.

A TED Talk:
http://www.youtube.com/watch?v=Y_9vd4HWlVA

The way light reflects off surfaces is very interesting. And mind boggling.

Bullgrit

 

[tomBitonti]

Nothing escapes from the singularity out beyond the event horizon to the outside world, no.

If scientists took "we can't see it, therefore it isn't there" as our clarion call, we'd never have discovered atoms...

Here's two things:

1) What math we have actually suggests the structure.

2) What you say is true holds for "vanilla" black holes. Once we start talking about holes that have angular momentum and electric charge, the space within gets far more complex and interesting. There's no reason for you to care about it unless you've fallen inside, of course....

On a quantum level, yes, when you're talking about the interaction of individual particles. Well, what we do is take the initial states of the particles, imagine they go into a box, calculate all the possible interactions within the box, and come up with a probability distribution for what comes out box. This is QM, it is all about probability distributions.

This fails when you want to talk about the action of a prism or lens, however, as the number of interactions that can occur when passing through a macroscopic chunk of material becomes too high to contemplate.

I'm (mostly) not suggesting this is a good way to understand black holes. I just find it very curious that there is no way to observe the internal structure without performing the irreversible step of crossing the event horizon. My understanding is that, according to known physics, there is no way to transmit information outside of an event horizon. (With particle histories encoded in the topology of the horizon, such that there is no information loss.) The reason to believe in an actual singularity is that even if the singularity does not exist, the details of the description put it back in (functionally) anyways. There is no conceptual benefit to be realized. Except, it does avoid extreme points in the mathematics.

Spinning black holes and ones with charge get a lot more complicated ... with multiple horizons and what not. I understand that there are conditions which could conceivably produce a "naked" singularity, but I also thought that to reach this condition the physical conditions are even more extreme than those of a "normal" black hole.

The view for photon transmission is a thought idea. The implication is that the receiver knows (somehow) exactly when to change state to balance the change in state of the transmitter, including the time and phase differences and possible paths, which feels implausible. It's action at a distance taken to the extreme. I also understand that accounting for the energy of the photon as it transits gets to be a mess if the transition is not made as a continuous transmission across space.

Still, the descriptions of particle motion which talk about "sum over possible paths" and what not seem to push us in this sort of direction. One gets curiously close to a description that might arise if the whole system were being simulated using discrete techniques.

In the end, what I've been told, is that you can use either view and obtain the same results as current explanations. That is, in the details of the mathematics, the actual presence of the singularity is more of an interpretation type question, not one which must be answered to obtain use from the mathematics.

Thx!

TomB

 

[Scott DeWar]

who can explain things to my level without making me feel like a complete moron is quite lovely.

Bullgrit

ditto this!

By the way, just saw the you tube on the femto camera. Wow!

Also what showed up was the video on superconductors. Something mentioned was its ability to hold a charge as long as it is kept cold. If the efficincey could be achieved that it could hold a charge during night time for solar panels or on windless days for windmills, that would turn the total power grid problem of using non-fossil fuels into reality!

 

[freyar]

This is why I ask these kinds of questions. Because I want to understand how it all works, not because I think I've found a flaw. When I see a "logical flaw" in physics, I figure I just need to have it explained more/better, not that I'm the first person to see the "flaw."

And I'm very thankful to have people here who are able and willing to take the time to explain things more and better (mo' betta) to me. I love science, but I'm only a layman, and many papers and books are written above my level. Having peers, like here, who can explain things to my level without making me feel like a complete moron is quite lovely.

Bullgrit

I'm in the same boat as you, man.

Have you ever read anything by Paul Davies? He's a physicist who write books that make arcane concepts fantastically accessible to laymen. I never really understood what relativity was about until I stumbled across his book "Other Worlds" a few years ago. Since then I've gobbled up anything I find by him. He has an amazing gift for explaining stuff: quantum mechanics, gravity waves, dark matter, unified field theory and even a bit of string theory (although even Davies admits that string theory is pretty much pure math). Also, he's not afraid to dabble in more speculative stuff like the possibility of alien life, whether we're all living in a computer simulation, and the ever-popular question of whether god exists (Davies is agnostic).

Personally, I wish I could understand a bit of the math, but mathematics really is its own language. When someone says "Here's the basic equation behind X..." and then there is a string of Greek characters, I feel a bit out of my depth.

And I'm really glad that you (and others here) can ask these questions; it's a real compliment to Morrus and the mods that there is a space for it. I also don't want to say that I've really noticed anyone here claiming to have found a flaw --- those people wander into my office, send me emails, etc. I've been fortunate never to have been threatened with a lawsuit for ignoring someone's pet "theory" (in quotes because of no mathematics), but I've known people who have. Anyway, I'm just saying that these threads are an enjoyable form of public outreach for me, and I also find that a lot of you have a pretty strong appreciation both of the facts and subtleties involved.

 

[freyar]

I'm (mostly) not suggesting this is a good way to understand black holes. I just find it very curious that there is no way to observe the internal structure without performing the irreversible step of crossing the event horizon. My understanding is that, according to known physics, there is no way to transmit information outside of an event horizon. (With particle histories encoded in the topology of the horizon, such that there is no information loss.) The reason to believe in an actual singularity is that even if the singularity does not exist, the details of the description put it back in (functionally) anyways. There is no conceptual benefit to be realized. Except, it does avoid extreme points in the mathematics.

Spinning black holes and ones with charge get a lot more complicated ... with multiple horizons and what not. I understand that there are conditions which could conceivably produce a "naked" singularity, but I also thought that to reach this condition the physical conditions are even more extreme than those of a "normal" black hole.

As we've been saying, physics is what the mathematics tell us. It's not that there's a conceptual benefit or not to the singularity. In Einstein's general relativity, it is just there (inside the black hole). However, you can ask if that means there is a problem with relativity at the energy densities and curvatures you'd find at or near the singularity inside a black hole. Most people believe that, yes, there is a problem, and general relativity is modified in some way so that the (modified) mathematics gets rid of the singularity. This is a fairly big area of research among people who study gravity.

The view for photon transmission is a thought idea. The implication is that the receiver knows (somehow) exactly when to change state to balance the change in state of the transmitter, including the time and phase differences and possible paths, which feels implausible. It's action at a distance taken to the extreme. I also understand that accounting for the energy of the photon as it transits gets to be a mess if the transition is not made as a continuous transmission across space.

Still, the descriptions of particle motion which talk about "sum over possible paths" and what not seem to push us in this sort of direction. One gets curiously close to a description that might arise if the whole system were being simulated using discrete techniques.

I'm not sure what you mean about the receiver changing state "to balance the change in state of the transmitter." Quantum mechanics doesn't say this. What it says is that we can only know the state of a system at a measurement event, and, if we know a particular measurement, we can predict the probabilities of the different outcomes of a subsequent measurement. The calculation of these probabilities can be described as the sum over paths. I'm also not sure I understand what you mean about accounting for the energy of the photon being difficult.

 

[tomBitonti]

I'm not sure what you mean about the receiver changing state "to balance the change in state of the transmitter." Quantum mechanics doesn't say this. What it says is that we can only know the state of a system at a measurement event, and, if we know a particular measurement, we can predict the probabilities of the different outcomes of a subsequent measurement. The calculation of these probabilities can be described as the sum over paths. I'm also not sure I understand what you mean about accounting for the energy of the photon being difficult.

It's looking at the physics by only interpreting the endpoint events: A photon is emitted; somewhat later, somewhere else, subject to spacetime, curvature, interference, and probabilities, a photon is absorbed. That the photon crosses space is looked at as a bookkeeping detail: Figuring out where the photon will be absorbed. The intrinsic event is the emission and absorption, together as one unified event, which happens to occur at two different points in space-time.

That's what you might do if you were making a simulation, and only cared about the emit and absorb steps. Computation of the path that the photon took (or could take) would be a way of figuring out where the absorb occurs.

Thx!

TomB