Space Sciences Black holes: what are your thoughts?

[nog]

However, as you fall in, you'd forever see an event horizon in front of you, even after you cross the black hole event horizon.

Sorry, you wouldn't see it forever below you, because in a finite amount of time you'd reach the singularity. If you weren't somehow magically destroyed by tidal forces you'd just get closer to the event horizon until you, the event horizon and singularity were all at the same point.

Assuming a black hole already exists.

 

[Blobbenstein]

I agree. Which is really the only reason why, to me, one can say it takes an infinite amount of time for a black hole to form, therefor, they cannot exist (as a singularity). Or at least not yet, unless time has passed for an infinite amount of time already, then I'd admit that black holes could exist.

So, if an event horizon BH doesn't form, what do we have, when a ball of matter can no longer support its own weight?

 

[nog]

So, if an event horizon BH doesn't form, what do we have, when a ball of matter can no longer support its own weight?

In my opinion, if we look at a forming black hole, just before it becomes a black hole we see that the more the star collapses (from a perspective of an outside observer) the slower time goes for that surface of the star, so it just remains an object that is collapsing to the Schwarzschild radius, getting slower and slower, but never reaching the Schwarzschild radius, because at that point we'd require an infinite amount of time (with respect to a distant observer).

An analogy would be that it's not much different (when dealing with infinity) than an attempt to reach the speed of light. You can continually get closer, but never reach it, since it'd require an infinite force (from an outside observer).

I guess that's why I like the term frozen star better than a black hole.

--

Please keep in mind this is counter to the generally accepted ideas in astronomy/astrophysics.

 

[ledboots]

:walks in, looks around confused. Exits:

 

[das_nut]

So, if an event horizon BH doesn't form, what do we have, when a ball of matter can no longer support its own weight?

A naked singularity. Which may or may not be possible (depending on what theory you're using).

 

[Envy]

It doesn't seem like a huge improbability for black holes to exist.

I could probably chalk it up to me not knowing the intricate details about space-time and its relation to black holes and light.

 

[FortyTwo]

In my opinion, if we look at a forming black hole, just before it becomes a black hole we see that the more the star collapses (from a perspective of an outside observer) the slower time goes for that surface of the star, so it just remains an object that is collapsing to the Schwarzschild radius, getting slower and slower, but never reaching the Schwarzschild radius, because at that point we'd require an infinite amount of time (with respect to a distant observer).

An analogy would be that it's not much different (when dealing with infinity) than an attempt to reach the speed of light. You can continually get closer, but never reach it, since it'd require an infinite force (from an outside observer).

But this doesn't make sense. It doesn't require an infinite force. There's a reason we call it the speed of light, because light goes at that speed. Photons and other massless bosons aren't acted on by an infinite force.

 

[nog]

But this doesn't make sense.

If it doesn't make sense, I suggest that you study special relativity.

It doesn't require an infinite force. There's a reason we call it the speed of light, because light goes at that speed. Photons and other massless bosons aren't acted on by an infinite force.

It does require an infinite force. One need only review relativistic mechanics. The energy required or the force required is infinite.

The discussion was about an object falling into a black hole and as such an object starting at slower than the speed of light (hence the reason I specifically stated "an attempt to reach the speed of light") and attempting to reach the speed of light. In this case the discussion was referencing an object (i.e. something that has mass). I was not referring to massless particles (which, if I remember correctly all move at the speed of light, not slower. Unless we're talking about them moving inside a material/medium, but that's not really relevant to this discussion).

 

[Blobbenstein]

I think it is better to just say that matter can't travel at the speed of light....an infinite amount of energy isn't a real quantity.......I found it very confusing when I was a kid, when someone on TV said that it would take all the energy in the Universe(more than?) to get something to travel at the speed of light, and I was like, 'well how much energy is that then', and then thought in terms of working how much energy was in the Universe.

 

[nog]

I think it is better to just say that matter can't travel at the speed of light....an infinite amount of energy isn't a real quantity.......I found it very confusing when I was a kid, when someone on TV said that it would take all the energy in the Universe(more than?) to get something to travel at the speed of light, and I was like, 'well how much energy is that then', and then thought in terms of working how much energy was in the Universe.

I agree, but then there are always those asking the "why?" According to the mathematics at the limit where some quantity (the force acting upon an object or the energy required) goes to infinity in the relativistic equations we see that the relativistic velocity is indeed the speed of light.

I agree though, perhaps infinity is used to casually.

 

[Blobbenstein]

My understanding is that Hawking radiation is just black body radiation (details in thermodynamics). However, Hawking radiation specifically was trying to show, using QM, how this process occurs.

would black body radiation be enough to radiate away all the matter in a collapsing ball?

I have been told that Hawking radiation can be particles like electrons etc, allowing the radiating away of charge, say if the BH was negatively charged, which wouldn't be possible with just EM radiation.

 

[FortyTwo]

If it doesn't make sense, I suggest that you study special relativity.

I'm sixteen! The fact that I at least know how subatomic particles work deserves a little credit. I'm guessing you have at least a college degree in the stuff. I've had to independently learn about the standard model because high school is useless if you want to know about science.

Would you be able to recommend me any good resources to getting started with relativity? I do love to learn about this stuff. Not sure if I'll fit in the current discussion here, though. A bit too advanced for me...

 

[nog]

would black body radiation be enough to radiate away all the matter in a collapsing ball?

I have been told that Hawking radiation can be particles like electrons etc, allowing the radiating away of charge, say if the BH was negatively charged, which wouldn't be possible with just EM radiation.

From what I remember it's black body radiation, but it's more complicated since generally black body radiation increases with temperature, with black holes, it's the opposite. So as the black hole gets larger it emits less, which means large black holes might have more incident radiation (say from nearby stars or simply from the CMB (Cosmic Background Radiation)). So some larger black holes might not evaporate.

However this is assuming a black hole already exists.

I'd have to re-read Hawking radiation, but I think there are a lot of possibilities for the method of what creates it. Since it hasn't been observed (I assume), I really don't know.

 

[nog]

I'm sixteen! The fact that I at least know how subatomic particles work deserves a little credit. I'm guessing you have at least a college degree in the stuff. I've had to independently learn about the standard model because high school is useless if you want to know about science.

Would you be able to recommend me any good resources to getting started with relativity? I do love to learn about this stuff. Not sure if I'll fit in the current discussion here, though. A bit too advanced for me...

I apologize if what I said came off rudely. I did study Physics as an undergrad and grad student and started in the 90s. Astronomy/astrophysics/cosmology are of particular interest to me.

It's been awhile for me, so I'm enjoying refreshing my memory about this stuff. I even got out my text book that I used when I studied special relativity.

I'm sorry too if I'm coming across as a know-it-all. I don't know it all (I don't know much really) and I may be wrong in my position that black holes don't form (just one of many examples).

I'm sure there are quite a few more options to study special relativity now, including online, than there were when I started. I'm not familiar with any from over the last decade. The text I used (and still have) for Special Relativity was Understanding Relativity by Leo Sartori. It's great and covers the subject well. While some parts require knowing Calculus, most only requires knowledge of Algebra.

Relativity is a challenge, because a lot of it is counter-intuitive, but if you're comfortable with the math and what that means, it's not really too bad.

Really it starts with an understanding of inertial frames and Galilean inertial frames, then adding the two postulates of Special Relativity (something about all inertial frames have the same laws of physics, and then the second is that the speed of light is a constant; of course stated more precisely). This leads to a few things like simultaneity, length contraction, and time dilation. Probably a few more things.

Then the Lorentz transformations are added/derived. Then you can study paradoxes and resolve them.

Maybe if I find a good online introduction I'll let you know.

 

[Blobbenstein]

I read on a news page about black holes not forming of something called 'preHawking Radiation'; that is a HR type radiation that is emitted by collapsing objects.

 

[FortyTwo]

I apologize if what I said came off rudely. I did study Physics as an undergrad and grad student and started in the 90s. Astronomy/astrophysics/cosmology are of particular interest to me.

It's been awhile for me, so I'm enjoying refreshing my memory about this stuff. I even got out my text book that I used when I studied special relativity.

I'm sorry too if I'm coming across as a know-it-all. I don't know it all (I don't know much really) and I may be wrong in my position that black holes don't form (just one of many examples).

I'm sure there are quite a few more options to study special relativity now, including online, than there were when I started. I'm not familiar with any from over the last decade. The text I used (and still have) for Special Relativity was Understanding Relativity by Leo Sartori. It's great and covers the subject well. While some parts require knowing Calculus, most only requires knowledge of Algebra.

Relativity is a challenge, because a lot of it is counter-intuitive, but if you're comfortable with the math and what that means, it's not really too bad.

Really it starts with an understanding of inertial frames and Galilean inertial frames, then adding the two postulates of Special Relativity (something about all inertial frames have the same laws of physics, and then the second is that the speed of light is a constant; of course stated more precisely). This leads to a few things like simultaneity, length contraction, and time dilation. Probably a few more things.

Then the Lorentz transformations are added/derived. Then you can study paradoxes and resolve them.

Maybe if I find a good online introduction I'll let you know.

No, no, of course not! It's just that I continually get myself wrapped up in arguments I don't have the proper knowledge to understand.

Thanks for the advice, I'll look into it!

 

[nog]

I read on a news page about black holes not forming of something called 'preHawking Radiation'; that is a HR type radiation that is emitted by collapsing objects.

Interesting. I'll have to look into it.

I would assume a proto-black hole (or frozen star) would evaporate before it actually formed, due to black body radiation and perhaps others.

I should really catch up on some of this.

 

[FortyTwo]

 

[FortyTwo]

I ended up actually reading into relativity, it's not that bad, in fact it makes quite a bit of sense and challenges a few of the notions I had about light and time. I still see no reason a black hole can't form (especially if Stephen Hawking says it can, because I'm inclined to believe him) but then again I know almost nothing about the math behind this (unless you count light cones as "math").

Only bumping this thread because I'm still mad about NASA and am therefore using tonight as a Science Night and not a TV Night.

 

[Blobbenstein]

Einstein didn't think BHs could form, I don't think.