GRAVITY PROBLEMS -- off topic from {Falsifying a young Universe}

I like it. I take SG's criticisms, but for 5 mins it's damn good. It is historical, and as much as I favour the Minkowski approach, it is not part of the historical development of SR.My only dislikes were the the very quick introduction of light (could have had a 20 second connection to the moving charges) and the talk around E=mc^2 helping perpetuate the horrible myth of nuclear power converting matter into energy in some way. This is one area I like to take the fifth over until I'm satisfied with the understanding of the recipient.

Oh, you've got to smile If you haven't yet seen him talk, make the effort before he leaves us. I still kick myself for not managing to catch Feynman.Penrose and Rindler is much worse than Road to Reality. Here they do not assume you are a lay reader...This message has been edited by cavediver, 10-12-2005 08:06 PM

It's all about a confusion of terminology. There's nothing wrong with these statements if you understand the nature of matter and mass. It's just that very few people do understand these concepts.It is often said that mass/matter has energy. It would be far better to say that energy has mass.Strictly speaking, matter means fermions. Fermions are matter-like in that they are distinct entities and usually their number appears to be conserved.Bosons are not considered matter-like becasue they are not distinct. You can stick as many photons on top of each other as you like, and they blend together. Their number is certainly not conserved. They come and go at will (well, by the rules of QED and QCD!) This makes them more energy-like.But both fermions and bosons have mass by virtue of having energy.So when we say matter to energy, there is an implication of fermions disappearing and photons being released. This happens, it's called matter-antimatter annihilation or simply pair annihilation. An electron and a positron (antimatter electron) can annihilate to produce two photons: matter to energy. The reverse is equally true, energy to matter, and we call this pair creation.The protons in a nucleus are under massive pressure to fly apart by electrostatic repulsion. They are all positively charged... They are bound together by an insane interaction of virtual bosons and fermions. There is huge energy in these particles, and hence mass. If you split the nucleus, this energy is released. You still have the same number of quarks as you started with, but the mass has dropped becasue there is no longer this huge binding energy.So the mass of an atom is the mass of the protons, neutrons and electrons plus the mass of binding energy within the nucleus, plus a little for the mass of the e/m binding energy holding the electrons in place. It is the e/m binding energy that gives rise to chemical energy.The binding energy in the proton or neutron is orders of magnitude larger again. When you think that the mass of a proton is at least 60 times greater than the mass of the three quarks from which it is made! That's rather a lot of binding energy available for your quark bomb!

Simple, if you want to "learn" by reading comments scribbled on the internet, then fine. But don't waste other peoples' time with it. Why do you believe that this site has any authority to make a claim like that?

And you know this because... And you know this because...You seem to think that you know a great deal about how we do things.

How do I do this other than by telling you that we do know... as well as we know anything else in reality. As I said before, we understand gravity far better than most of the everyday occurances that you experience. You are just not being as demanding of your everyday experiences.Just becasue many people on the web say that we do not understand something does not make it so. How many of them are talking from a position of knowledge? This is difficult stuff... for the vast majority of people, gravity is an unknown. You see, Simple, with this kind of attitude, why do you expect me to bother even writing this reply, never mind a long and detailed explanation of gravity that you may be be able to comprehend? Wasn't me.And anyway, Feynman was lying. He was very good at it. It was how he kept students focussed on their level rather than trying to get ahead of themselves. This is one way that physics is taught. This is where I get unstuck becasue I don't like lying, and I end up trying to explain too much. It is not helpful for the student.

Thanks Sidelined. I really do not have the patience to teach those unwiling to learn (does it show ) That is why of the two of us, my wife will always be the far more effective teacher...

You know, trying to argue with a scientist about his field, using information pulled from the internet or "popular" science publications just makes one look very stupid. From where do you think this information came in the first place before it was bastardised and distorted? John's (Baez) and Carlo's (Rovelli) work is just a part of what we do (or did in my case). You think this stuff is new to us? Do you think that this is "bizarre" to us? This is the bread and butter of theoretical physics. There is no rethink. Do you have any clue as to the role of maths in all of this? Your question is non-sensical until you understand what you are asking. And once again, there is no rethink from the point of view of theoretical physics.This message has been edited by cavediver, 10-16-2005 07:33 AM

Yawn When did you last chat to Einstein or Feynman about your ideas about their fields? I unfortunately never got to meet Feynman, but a couple of my friends knew him well... from what I understand, he would have had about a thousandth of the patience with you that I have. Funny, it was the other way around this morning at church. But then my church has always been rather heavily creationist.

What are you talking about? What money? Do you think theoretical physicists are well paid, or funded by industry, or Disney or something??? If someone approaches me and says "Ha, you think you know about gravity, but actually you know nothing... look what it says on this internet site, doesn't this just show how you scientists have got it all wrong" I tend to get a little shirty.If, on the other hand, someone approaches with a question or even a sensible and reasoned challenge (as with RAZD) I am more than willing to spend time explaining, conversing, and debating. Yes it is... issues surrounding stellar birth and evolution... not black holes, or any fundemental physics whatsoever. As I keep saying, you cannot trust popular science accounts of anything. Far from it, but all I seem to be getting from you and Simple is "ha ha, you know nothing". This is completely false. What do you mean? At what level? Time baffles the hell out of me, but that is at a much deeper level than you are thinking. But then it was my job for several years.Tell you what. Tell me what you do for a living, and I will then explain to you calmly how you know nothing about your trade, and how I, with no experience in your field, am suitably qualified to riducule your knowledge. Fair?

I never once said that there isn't more... not once. This was your assumption and also Simple's. This was someting else that I found offensive: because I am scientist involved in fundementral physics, it somehow automatically means that I am atheistic/agnostic. Try looking at some of my postings on other forums at this site. I am a Christian and attend a very lively evangelical, and largely creationist church.If you want to know about more than just the physical universe, read the Bible, or whatever religious/spiritual text you have in mind. Talk to your fellow believers and share their company. That is where you will learn of God... not by peering into physics/astronomy/chemistry or any other worldly pursuit and hoping that at some point a veil will be drawn aside and you will experience a full gnostic revelation. The last time that was tried the number of languages on the planet shot up a bit.God's created world is an awesome place, and I had incredible joy from delving deep into its mysteries. It was a great privilidge for which I still thank God. I do not like it when others (Christian or not) make light of this...

There was no reference at all to money. Scientists (in my field) survive on the science... and this was my menaing... the money is secondary, tertiary, or even irrelevant. These days I hang out with climbing and caving "bums", but I've known many science "bums". Of course. Time is a physical part of the universe... one dimension out of four (or more). In a finite universe BB scenario, time began at the BB. In a closed BB scenario, time ends at the final crunch. It is a totally integral concept to the physical universe. Even in an eternally existing universe, time is still just a physical concept. One of my favourite space-times has an infinite number of eternal universes, all connected in pairs by an infinite "corridor". If you travel through the corrdior, you can pass by entire enternal universes. And this type of thing is very basic... this is studied at masters level GR.

If you want to debate this stuff, please at least get the basics right. This is so wrong it is laughable. Who told you that the original premise was "something came from nothing"? Nothing could be further from the truth. Why do you think Einstein made his "greatest mistake"?Do you realise that there were huge objections to BB precisely because it introduced a beginning to the universe and this smacked of creation, especially when used with the wholly inappropriate soundbite "something came from nothing". The leading theory at the time was Steady-State which has an eternal universe, and many used this as a dismissal of creation and/or God. BB was too religious for many atheistic scientists. However, evidence mounted to dismiss the "atheistic" steady-state theory and force general acceptance of the "theistic" big-bang theory.The simple fact is neither BB nor steady state (nor any other theory of space-time) proves or disproves a concept of creation. You can just as easily have a creation of an eternal universe as a finite universe.Hope this clears things up a bit...Now, would you like to explain the physics of your split/merge theory? How it generates the observed CMB, the observed ratios of nucleosynthesis, the observed expansion of the universe, etc? You know, all that evidence for the BB scenario that you think is lacking...

Just to add to SG's comments: It does in d=2 And it should be pointed out that "quantize" means to take a classical theory and use it to extrapolate the quantum theory. It does not mean that there is not a quantum theory of gravity, just that our usual prescriptive (and rather crude) methods of getting a quantum theory from a classical theory do not work.

Yes, in a cheating sort of way, becasue there are no dynamical degrees of freedom in d=2 GR, so the quantisation is essentially "trivial"... great word This is what's so great about topological gravity, in that you "twist" out all of the dynamical dof and you're left with an exact quantum theory even in d=4. Topological field theory is an awesome subject...But I'm going to bed, so if you want to talk more about it you'll have to wait Almost certainly the latter... but this is essentially string, M and loop. It's bound to be M as M could be anything!