Black Holes, Singularities, Confusion

Yeah, new thread time I think. I haven't really dived in to the depths of this while here at EvC though I have often touched upon it. Not long after discovering EvC I got into discussions over this issue but I didn't make a good job of presenting the subject - I hadn't before discussed this stuff at an academic-ish level away from practioners of the field and I was surprised by the lack of familiarity and the resistance to the ideas. When you have been immersed in a field for so long it is difficult to appreciate how little of the realities of that field make it out to the general academic public, including physicists and mathematicians. This has been how funde physics has progressed for the past 100 years so it's not really new! And we don't work on this basis because we like mathematics (though most of us do ), but becasue it works and works better than phsyics has ever worked in any other area. But we can talk all about this in another thread.One thing to remember is that "equations" are our representations of the mathematics. By mathematics, I am talking about pattern and symmetry, as expressed through areas such as geometry and topology. Yep, that's how I'd put it. Not dumb. It is very similar, though the SE is non-relativistic. In its relativistic cousins (Dirac Eqn, Klein Gordon Eqn) that's exactly how it appears. To the relativist or quantum theoretician, you may as well talk about your attachment to creationism

No problem, but to be just given the remit "explain black holes in layman's terms" is a little daunting given my limited time and the size of the subject! Questions are always well received

my problem--I don't know the questions to ask, so either someone else will have to, or, you can just to installments every know and then.Perhaps after your first "intro to the layman" I'll have questions.It's sort of like asking a three year old to ask why 2 + 2 = 4, when they don't know what 2, +, =, or 4 is.

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Ok, here's the one I came up with when I was eight. It's a bit embaressing that it took me so long, as I'd been reading about black holes for four years by then

quote:

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just because the gravity of an object increases to the point that light cannot escape, why should that invoke tales of wormholes, other universes and time-travel? Why could it not just be a super-dense object (maybe crushed to a point) and the event horizon simply be the region within which light cannot escape?

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Try that one...

while nwr, Percy, and cavediver have already done a great job of answering your questions, I would like to point another (possible?) missunderstanding present in your post.You seem to believe that there is some intrinsic limit to the energy that a particle may have. That is not the case. The relativistically correct formula for the energy 'E' of a particle with restmass 'm' moving at the velocity 'v' is given byE=mc^2/squareroot(1 - (v/c)^2)As you can see, as the speed of the particle approaches c, the square root approaches zero and the energy approaches infinity (therefore no limit)

I share the same feelings, but I understand why Cavediver and company adopt a "mathematics is the only reality" attitude. When we model billiard balls using the equations of physics, we know that there is an observable reality beyond the model. But as we create models at smaller and smaller scales, as we approach the scale of the atom and below, it becomes less and less clear whether the objects we're modeling have any reality that can be visualized. That's because objects at tiny scales have never been visualized. Their existence has only been inferred from data.The atom is good example of this conundrum:How accurate is this picture? Are protons and neutrons actually hard balls glommed together in the nucleus? Do electrons actually revolve around the nucleus in real orbits? This picture is a great visualization, but does it lead us to insight or error?The picture isn't completely useless because we do know that most of the mass of the atom is in the nucleus, and we do know that electrons reside outside the nucleus. But the only sure way to figure out what an atom will do is to apply mathematical models. And as you drop below atomic scales to the level of individual particles and to their quark sub-components the usefulness of visual analogs becomes less and less appropriate and more and more misleading. The only dependable way to know what is going on is to apply mathematical models, and that is what Cavediver is saying.Speaking for myself, the mathematics Cavediver is referring to is not accessible to me (I guess "accessible" is my weasel word for comprehensible), and so I must rely on visual models to which I have to attach a number of criteria, qualifications and corrections. Cavediver has an inherent dislike for such approaches and tends to be disparaging of them because of their capacity to be misleading, but given that the mathematics is beyond me I have no choice but to follow the course I can understand. I think most of us here are in approximately the same boat.--Percy

That's what I thought of too as a teen-ager and my brother who now teaches thermo was eight. I guess it is just the difference of generations. He was thinking of StarWars
StarWars.com | The Official Star Wars Website
& WormHoles. I passed that by with BattleStar Galatica.
Battlestargalactica
He however still thinks about intricate computer games and hikes in the Alps. I do not or can not. On reading Rene Thom about morphogenesis and singularities even the "thought" expts of Einstein remained somewhat fictional to me.Worm holes etc were science fiction enough for me not to go further than a cursory interest in Penrose, etc. until I heard by how much a Romance Studies Professor at Cornell was intriqued and enamoured of Hawking's book on Time. I do need to catch up on some ideas in physics.

Oh this is the exact kind of thing that would be excellent within a new thread. Yes it likely does uncover a misunderstanding I have.Let me try my hand at answering it from my errant conception. I did view there being intrinsic limits to the energy a particle may have, though I limited that to an area of space. I'd also alter my description to something more than a single limit. I was trying to suggest that specific energy "limits" are reached where they may collapse into a stable form within an area (localized stable space-energy field) we'd call a particle.Remember the preceeding is a manifestation of my ignorance and not something I am trying to champion as the "real physics".Regarding your direct point, as a particle approaches c doesn't it essentially lose "particleness"? It was my understanding that as energy is pumped into a particle to that degree (say in an accelerator) the chemistry is not known to remain the same and the end result may be the creation of many more particles with all sorts of different characteristics?

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holmes {in temp decloak from lurker mode}
"What a fool believes he sees, no wise man has the power to reason away." (D.Bros)

Yeah, I get it too. Especially when practical results keep coming out of it. But I keep wanting to change that to "mathematics is the only way to understand/observe reality in extreme environments".I definitely understand your analogy to inaccuracies in atomic models. I think maybe one of the larger problems for me is that the subject matter for GR, SR, spacetime is more ephemeral than discussing the nature of particles (from a strictly chemical viewpoint).Whatever skill I had in math (which was pretty high, doing rudimentary QM and all) has since rusted so badly I look at the equations and can't believe I once understood stuff like that. So I'm definitely stuck in the same boat you are, even if cavediver feels it might be sinking.I'm now spending time reading more about physics... and everyone's posts have helped me both to get a firmer grasp, as well as drive an interest to get it right. I'm thinking I'll have a new thread to work out more of my issues in a few weeks. Heheheh... cavediver may have to put up with some lack of math ability, but I'm sure he can do it!

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holmes {in temp decloak from lurker mode}
"What a fool believes he sees, no wise man has the power to reason away." (D.Bros)

Spot on. I was actually going to present exactly the same scenario to explain my position, but you have saved me the effort and made a better job of it.

I particle does not lose its identity when moving close to the speed of light. It's only when it collides with other particles that its kinetic energy gets released and become available for the production of other particles with different caracteristics. Remember that by relativity principle a particle velocity is relative.

Thanks for posting the diagrams, but can you explain something for me... why is "diagonal" (at 45 degrees) the fastest one can travel through space? Could we not (in theory) have someone traveling so fast that they travel purely through space (and hence, not through time) such that they'd be moving "horizontally" across the diagram?Greg P.

The speed of light, known as c and equal to 299,792,458 m/s, is the speed limit for all velocities. A 45 degree line corresponds to the speed of light. A line greater than 45 degrees would correspond to a speed greater than light and so could never happen.Another way of looking at it is to realize that just because you can write 1 billion m/s, about 3 times faster than the speed of light, that doesn't mean that anything can go that fast. In the same way, drawing a line greater than 45 degrees that corresponds to a speed greater than light also doesn't mean anything can go that fast.Cavediver's diagram is a convenient visualization, but it has a few rules you must follow if the diagram is to correspond to reality, and one of them is that you can't have lines greater than 45 degrees.--Percy

A prime example of my entire collection of rantings and ravings. We can infer and deduce to our hearts desire but at the end of the day we are still limited by scientific precision. But to cloud the terms reality and visualization are a bit of a leap. The fact that we cannot detect, observe, measure, or record the existence and interaction of supersubatomics has no bearing on reality. It may bear on our group consensus that we call a "model" or theory but again I state that it is pure ignorance to be so closed minded as a scientific community to think that we have reached the limit of all possible scientific precision and we have a solid enough foundation to base laws upon. Someday hopefully we can globally step back for a moment and consider the possibility or probability of true infinity, the possibility that our big-bang or pocket of space-time is one of an infinite number of such pockets, and the possibility that time, space, and energy exist in all directions both small and large as a fabric with which we perceive reality upon.

Hi Greg, welcome to EvC Good question, but some difficult concepts on their way! It is a little appreciated fact that the speed of light limit is actually only for external observers, in the sense that you as a traveller can travel as quickly as you like, up to infinite speed! That is, if you define speed as known distance to your destination divided by the time it takes you to reach that destination. So for example, as you accelerate towards Alpha Centauri (4.3 ly away), you start to notice that you are getting closer to Alpha C far more quickly than expected, so much so that soon you are far exceeding the speed of light. How? Well, we are used to talking about time-dilation on such a trip but often fail to realise what this means in respect of our perceived velocity. There is also the effect of Lorentz Contraction: lengths shrink at relativistic speeds - the most important length is that between you and your destination! At the speed of light itself, your perceived distance to Alpha C becomes 0, and so the time to reach Alpha C is 0! So you have actually travelled 4.3 yrs in 0 time > infinite velocity.Ok, so what about "space-like" travel, which would be lines greater than 45 degrees on the diagrams. Well, hopefully you can appreciate that these no longer conform to our ideas of "speed" and "travel". If at c, it takes your zero time to travel any distance, what can "faster" than this mean??? Time doesn't "tick" along these space-like paths, so you could never be conscious of such a path. There is no definiton of future and past on these paths. You can teleport or wormhole from one point on this space-like path to another, but this isn't what we usually mean by travelling faster than c. This is cheating However, any time you cheat, you are also creating a time-machine because of this lack of distinction between future and past.Don't worry if the above is too confusing and/or generates ten more questions. Ask away And before anyone says anything, yes this is intimately connected with black holes and needs to be appreciated.