Hadron Collider back online

It's amazing, isn't it? This place has more theoretical physicists than the Institute for Advanced Study. And they make fine additions to our faculties of climatology and economics. d8-)

i saw this cartoon in the newspaper and thought of this thread, laughed out loud.

(went around in circles trying to find an on-line copy of this cartoon, couldn't find one.)

LOL!! Good one.

EH:

Heh, naww I think you're putting too much on it. Machinists can often be a curious sort, and they are just asking questions about the world around us.

The questions are great. It's the ones who come up with answers who make me do a double-take. d8-)

Cliff:

By "Bound Systems" of photons, do you mean matter particles?

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Pair production refers to the creation of an elementary particle and its antiparticle, usually from a photon (or another neutral boson). This is allowed, provided there is enough energy available to create the pair... ================================================================

You'll have to give an example of this. It sound like saying "Stopped Motion", which on the surface of it seems incongruent.

Our conservation laws are human mental constructs derived from observation. Our mental conjectures are not necessarily binding on existence itself.

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Law of conservation of matter

A fundamental principle of classical physics that matter cannot be created or destroyed in an isolated system =================================================================

Now IF you had closed system, say a perfectly reflecting box filled with equal numbers of electrons and positrons, after a short period of time the electrons and positrons would annihilate each other into energy. So that would be a violation of the Conservation of Matter Law. Special Relativity kind of put a monkey wrench in that law.

Now the Conservation of Mass/Energy Law would still hold, since the contents of the box would have the same "mass/energy" before & after the particles annihilated themselves.

*BUT* even this LAW can seemingly be violated in certain local & short time frames plus other instances. Vacuum fluctuations (the creation of virtual particles), if viewed in a short enough time frame could be considered a violation of the Conservation of Mass/Energy Law, since they are created out of vacuum. But since the virtual particles usually annihilate each other in short order, this violation is overlooked. But in Hawking radiation, where two virtual particles are created out of the vacuum surrounding a Black Hole and where one of the particles is drawn into the Hole and the other one escapes... it becomes a REAL particle. Then you could interpret that as a local conservation law violation. Even though this violation can be averaged out over the whole universe and appear to not exist.

The Big Bang could be nothing more than a runaway vacuum fluctuation. It could be the result of a Big Crunch from a prior Big Bang. Bang - Crunch - Bang - Crunch and so on. There are other possibilities, but they lay outside the realm of physical science.

EH:

Yeah, I'm with ya there. There are few absolutes, the scientific method is a continuous never-ending process for arriving at a more and more accurate explanation of the world around us.

Speculations-R-Us.

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Guys back at SLAC are rolling their eyes.

Mart>> Physics hasn't been stalled - there is a lot of things to look into.

I don't know - the 70's and 80's brought us the tiny particles we dreamed about in Atomic and Nuclear physics. One needed big big toys

to discover quarks and hadr>> I say without a doubt. I've looked at the equations and diagrams.

OK, Martin. I just finished reading a fairly weighty book that put M-theory into context, and I'm aware of the current developments in the algebra of branes, but I'm certainly not going to argue it with you. For me, it would be even nuttier than arguing about global warming. I know nothing about the depths of climatology and I know even less about theoretical physics. And the more I read (a fair amount for a layman) the more I realize that I don't know. The interesting thing is that I've reached the point where it appears that no one else knows, either.

I'll just say this: There is no agreement among theoretical physicists that they are any closer to solving the problem of quantum gravity than they were

30 years ago; nor are they any closer to solving various other unifications and other problems with gravity. This I don't "know" in the sense that I understand the math or the physics. I "know" it in the sense that most of the leading researchers in the field, including Witten himself, who came up with the M-theory conjecture, stop short of saying they can see where their theories are going -- if they're going anywhere at all. Furthermore, most of them, except for the (almost politically driven) string-theory acolytes, seem to feel that we don't yet have a mathematics that can carry us any closer to resolution of these issues. And string theorists have had to live for decades with the fact that there have not been any experiments conceived that could test any of their fundamental ideas. Nor do they have any idea where to look for them.

If I were a scientist, this would drive me into another line of work. However, I'm glad that it doesn't seem to have stopped the physicists. As a science enthusiast all my life, I've been astonished to learn over the past few years how little is known at the bleeding edge, and how difficult it all is. The subject is one that I do not have the brainpower to tackle. I don't mean I don't have the commitment or the background; I mean that the sheer mental horsepower required is in the stratosphere above my head.

Edward Witten laid out the conjecture for M-theory 14 years ago, and it hasn't changed since. What the new work suggests is that there *may* be a possibility of understanding the fundamentals of M-theory. That's what the physicists seem to be saying.

I'm sure there are some who, in their layman's writings, make it sound like much more than that. Smolin has noted that there's been a tendency to make extreme claims for M-theory in the popular literature which aren't borne out by the facts. Again, I have no way of knowing. As with climatology, all I can do is use my sniffer to see who sounds like he knows what he's talking about, and, even more important, who has his head screwed on straight.

You win the big prize, Ed.

Anything from the top shelf.

There is what you know that you know, What you know you don't know, What you don't know you know, And what you don't know you don't know.

That last one trips up so many people, so often...

I read these books, like I read journal articles about medical research and a couple about climatology, and except for the medicine, I can't say I know any more about the first and last subjects than I knew beforehand.

But there is a benefit to it. One is something you suggest above, which is to get a better idea of what you don't know -- even if you know you'll never know it. In theoretical physics it can be a real eye-opener to read a good layman's account of the current state of the art, because the sheer volume of things I don't know is enough to warn me off from trying too hard. That doubtless has saved me a lot of time and frustration. d8-)

There's something else, which I've thought of writing about but I can't quite put it down yet. It's something like music. If you're lucky enough to get your hands on a really well-written book that's a bit over your head, about a subject that's way over your head, it might communicate the music, or maybe the poetry, of the subject. And that can give you a strong idea of what the subject contains, what kinds of people are doing it, what they know and not, and what they want to know and maybe will, or maybe won't, at some future time.

In other words, you can get the geography, or something like that, of a field, even when you won't ever be able to do it yourself. I like that about Smolin's book about physics, for example. It's beautifully written and musical as hell. Or poetic. But I don't really know any more about theoretical physics, per se, having read it. I think I know what I really need to know about the subject, however; not its content, but its phenomenology. But that word maybe is too grand for what I mean. This happens to me often when I'm reading 20th century German philosophy or French literary theory, too. Great music, but I still don't know what they're talking about.

Anyway, if I ever can find the right words to describe it, I'll try to do something with the idea.

I think you have a pretty good start right there.

Ed -

A good book is from several school mates - Katrin Becker, Melanie Becker and John H. Schwarz : "String Theory and M-Theory" A Modern indtroduction :: Cambridge University Press. 0521860695

M-theory (no relation to the letter :-) ) was derived from the mid 90's when the second superstring revolution took place.

Discovery is an on-going business in Physics. It covers from the smallest descriptive feature to that of the great cosmos. It is the foundation of many of the sciences and is a pure science. Some sciences are not science and some are meta-science.

Mart>> Wrong. Much closer on lots of things.

I appreciate the reference, Martin. Before I take on something as weighty and time-consuming as a book like this, I try to get a sense of it, to know what I would get for the time I would invest. Having read the publisher's description and a dozen or so reviews, I'm going to pass on it.

Apparently it is an introductory textbook for advanced undergraduates and graduate students in physics, and it's the conjectures themselves, rather than the contextual discussion that Smolin provides in _The Trouble With Physics_. I'm not interested now in a textbook of the conjectures. As a layman, I'm interested in what the field's top experts have to tell us

*about* the conjectures, in the broad context of the state of the art and science of theoretical physics. I'm not planning to do the physics itself.

So, like the physicists, I'll be waiting to hear what we learn from the LHC. It will be a long while, apparently, before the experiments touch on things that give us answers to what is real or not about string theory and its children. Meantime, it may be something like a particle version of the Hubble Telescope, simultaneously providing unsuspected answers and producing more questions. String theory, and M-theory, still have no real material with which to work. And now that I've been given some insight into the nature of these theories -- which, in science terms, are still conjectures -- it looks to me like one would have to be a committed physicist to be interested in working on them at this time. It looks to me like most of what those physicists have to look forward to is the proof or refutation of their conjectures. I have no conjectures to put to the test, so their game, and their interest, is not what I'm interested in. I'm curious about the realities themselves, and the chance we'll discover some new angles on them through experiment.

Real experiments will mean something but it's still not clear just what the LHC will produce in relation to those conjectures, because the practitioners can't even propose an experiment to prove or disprove their ideas. Perhaps the LHC will provide answers to the question of what questions might be asked. The Hubble did some of that for cosmology. We can hope that we'll see some parallels in particle physics, given this new instrument to probe things we can't see at all now.

But I do appreciate your thoughts and the reference.

MMMM, branes!

Dad took some N-dimensional and other unique classes at Cambridge many years ago. He was there 'under cover' cold war and all that - he was the system engineer and designer of what was to be the worlds most powerful radar - the top two after the new model years later. Some of the stuff he told me 30 years later was about what I expected - real time ion sorting of shorts. :-) I would have loved to attend Cambridge as a seminar student - and have plenty of time in the Ashmolean Museum to see what the old masters kept for the ages.

Martin

John Husvar wrote: