Black holes: event horizons and black holes.

3hr-marathoner wrote:

I'm no Einstein, but wrote:

No, you're wrong. Photons have energy and energy = relative mass. Engery is a source of mass.

I'm not wrong. You are confused. In relativity the energy of a particle comes from two sources: it's rest mass and relativistic kinetic energy. Photons have the latter but their rest mass is zero (as far as we know). Rest mass is essentially the energy of the particle if it isn't moving. Photons can't do that. They can't stop moving.

No, you're confused. The relativistic kinetic energy is relative mass. The rest mass is hypothetical, but since they don't stop it's never relatively zero mass/zero energy.

So explain how singularities form or how neutron stars form?

I'm no Einstein, but wrote:

3hr-marathoner wrote:

I'm not wrong. You are confused. In relativity the energy of a particle comes from two sources: it's rest mass and relativistic kinetic energy. Photons have the latter but their rest mass is zero (as far as we know). Rest mass is essentially the energy of the particle if it isn't moving. Photons can't do that. They can't stop moving.

No, you're confused. The relativistic kinetic energy is relative mass. The rest mass is hypothetical, but since they don't stop it's never relatively zero mass/zero energy.

trying to be diplomatic here...let's say we were both confused by how the other was defining terms. By "mass" I meant "rest mass." By "mass" you meant "total relativistic energy divided by the speed of light squared." Fine. Let's use your definition.

So in the context my criticism of the OPs (2) that it didn't deal with particles with zero rest-mass you want to take your definition of mass, m, from relativity (from the famous E = m c^2), then attempt to plug that mass into a Newtonian theory of kinematics and gravity to calculate the Swartzchild radius of a black hole? It's fine to try that as a back-of-the-envelope calculation but it's not a serious physics calculation because it doesn't make sense to use relativity for the mass of the photon but not for the gravity and the kinematics.

3hr-marathoner wrote:

Where did this rant come from? On a running forum no less? Yes, the term "singularity" is overused in the media but there are countless more important scientific things that the media gets wrong. Also (2)? Particles of light (photons) are massless so this "Newtonian event horizon" you are describing would not apply to light so it wouldn't be a black hole at all because light could still escape.

Light doesn't escape because it is drawn towards the center which has enormous mass.

Phew..... I thought this was yet another thread about Caster Semenya!

I'm no Einstein, but wrote:

3hr-marathoner wrote:

Where did this rant come from? On a running forum no less? Yes, the term "singularity" is overused in the media but there are countless more important scientific things that the media gets wrong. Also (2)? Particles of light (photons) are massless so this "Newtonian event horizon" you are describing would not apply to light so it wouldn't be a black hole at all because light could still escape.

Light doesn't escape because it is drawn towards the center which has enormous mass.

Neutronic reflectivity

I'm no Einstein, but wrote:

3hr-marathoner wrote:

Where did this rant come from? On a running forum no less? Yes, the term "singularity" is overused in the media but there are countless more important scientific things that the media gets wrong. Also (2)? Particles of light (photons) are massless so this "Newtonian event horizon" you are describing would not apply to light so it wouldn't be a black hole at all because light could still escape.

Light doesn't escape because it is drawn towards the center which has enormous mass.

I know but think this through. Particles of light aren't like bullets or baseballs. Light always travels at the speed of light which is a physical constant (as far as we can measure). Picture a baseball flying directly away from a massive object. It slows down as it goes. If it has a speed greater than escape velocity it go away forever, if not it turns around and returns. How do you picture this working with a photon since photons travels at a fixed speed? Instead of making this problem simpler the Newtonian theory is making this problem a whole lot harder and if you succeed in making your Newton theory work, you are just going to end up re-inventing general relativity because it's the simplest theory that deals with gravity and a constant speed of light.

i too hate when popular science articles don't provide the full unification of relativity and quantum mechanics in order to accurately describe black holes. seriously, how lazy can millenial journalists get?

Sheesh wrote:

I'd oddly be interested in the quantum mechanics one.

This thread though, should help with my training when near a black hole.

I tried a black hole once! ( and not only one time , thirteen times in 2 days and nights! ) A fantastic memory I will never forget until the day I die....

3hr-marathoner wrote:

Where did this rant come from? On a running forum no less? Yes, the term "singularity" is overused in the media but there are countless more important scientific things that the media gets wrong. Also (2)? Particles of light (photons) are massless so this "Newtonian event horizon" you are describing would not apply to light so it wouldn't be a black hole at all because light could still escape.

Zero mass objects are compatible with my model as a degenerate case, i.e., let m_min = 0 and therefore v_max -> infinity and gravitational even horizon r -> 0. Note, however, that the model was for a classical system with an additional set of specified axioms, i.e., total energy E and minimum mass m_min.

belial wrote:

I constantly see mainstream media, and even contemporary physicists, get basic points about the physics of black holes, according to relativity, patently wrong.

Hmm, so you're saying that sometimes experts oversimplify topics to make them accessible to laypeople? Crazy.

The singularity is probably only a mathematical abstraction, although current explanations about what space-time is are hopelessly confused so we cannot speak with any confidence on whether an asymptotic limit in time such as this can be obtained.

You seem to be pretty sure about what is and isn't true about black holes, though.

Why does the hole have to be black? Go back to Stormfront you racist. There is #nohatehere.

The universe used to be made of earth, wind, fire, and water.

The elements are now rocks (particles), fire (energy) and nothing ("space time" for the first two to exist in)

The first part of the paradigm resulted from physicists insisting on the belief that the nature of solid objects could be found by smashing them to bits until reached the smallest one, and ignoring that eventually the smallest ones weren't really objects anymore.

The second started out as a property of objects but had to be given more of an existence of its own to make up for the little rocks not really being rocks.

The third is an abstract concept that has to be pretend real for certain theories of the first two to make sense.

Rocks, Fire and Nothing.

Wigins we've all seen Captain Planet. You need general relativity for GPS clocks. Are you some kind of Kyrie Irving anti-science positivist?

Setting aside that the function of GPS clocks being consistent with GR doesn't mean GR is correct or even meaningful, you're completely missing the point that GR is essentially a grand theory of rocks, fire and nothing, like I said.

fire = rock x (speed of fire-rock)^2

"light" is either a fire-rock (massless particle) or a fire-nothing (wave in space-time). In either case the concept is basically something on fire, with no serious inquiry as to precisely what, beyond these primitive caveman concepts.

You really are simple.

What is a physical theory that gets at what things are?

Bad Wigins wrote:

Setting aside that the function of GPS clocks being consistent with GR doesn't mean GR is correct or even meaningful, you're completely missing the point that GR is essentially a grand theory of rocks, fire and nothing, like I said.

fire = rock x (speed of fire-rock)^2

"light" is either a fire-rock (massless particle) or a fire-nothing (wave in space-time). In either case the concept is basically something on fire, with no serious inquiry as to precisely what, beyond these primitive caveman concepts.

What things are is what physics is about. Isn't it? Is that somehow offensive?

So if you say a thing is a "particle," it might as well be a very tiny rock, for all you mean, because that's all the concept conveys ontologically. "Energy" might as well be fire. Something with kinetic energy is burning rubber. Something with thermal energy is hot, that's fire. A wave in space-time is a burning nothing.

Modern physics is a doomed creation of overspecialization in academics. Study philosophy - metaphysics - before physics or you'll have hopeless tunnel vision.

Bad Wigins wrote:

What things are is what physics is about. Isn't it? Is that somehow offensive?

So if you say a thing is a "particle," it might as well be a very tiny rock, for all you mean, because that's all the concept conveys ontologically. "Energy" might as well be fire. Something with kinetic energy is burning rubber. Something with thermal energy is hot, that's fire. A wave in space-time is a burning nothing.

Modern physics is a doomed creation of overspecialization in academics. Study philosophy - metaphysics - before physics or you'll have hopeless tunnel vision.

Labels, like "particle," have no inherent meaning (a rose by any other name). Structure is provided by other properties, like relations and functions. For instance, a set is an object defined by the member-of relation such that an element a is in a set X if (a,X) is in the member-of relation. A set in which a, b, and c are in the member-of relation may be denoted by the label {a,b,c}. This is just a label, but this label may be used in mathematical equations that impose some structure, e.g., the set denoted by {a,b,c} is a subset of the set denoted by {a,b,c,d}, i.e., ({a,b,c},{a,b,c,d}) is in the subset relation.

Generally, in physics, a set of functions are provided that map inputs to outputs, e.g., given some initial state, output a final state. This is what we call "prediction", that is, it makes a prediction about what will be observed given some observed initial input.

Because you seem hopelessly confused, I will take a bit of time to rumminate further on the philosophy of science in the context of the above. What use is prediction? This is a necessary component of scientific inquiry. Suppose we have a set of hypotheses A, and suppose exactly one of the hypotheses in this set is true and the remaining are false. To remove elements (hypotheses) from A, we perform experiments that generate observations and remove any elements that are not compatible (an incorrect prediction). This is called falsification. Typically, A is infinite, or at the very least has more than one element, and we often like to impose a partial order on the elements in A s.t. if a,b in A and a < b, we prefer hypothesis a to hypothesis b even though both are compatible with all previous observations. This order is where notions like Occam's razor come into play, which is an informal way to order the elements, but more mathematically rigorous orderings may be based on non-computable measures like Kolmogorov complexity for which Occam's razor is a crude though useful approximation.

Back to physics. In quantum mechanics, there are no distinct objects, only continuous fields as described by Schrodinger's partial differential equation. For all but the most trivial systems, the equations are intractable, although this is changing as we develop more efficient approximate algorithms and better hardware. Instead, we often resort to more classical mathematical structures that are easier to work with in which abstractions like distinct objects are available.