posted
I saw part of The Elegant Universe from Nova. You can watch it here under the third column.
From what I have seen, it looks really interesting. I never knew that unification of physical laws was such an important component of physics. Or is it?
Why do we need to combine the laws of gravity with laws that govern subatomic particles?
I am not sure I understand string theory and the significance it has to offer.
Are there any insights from those more educated in the hard sciences?
I am not quite all the way through, because I am at work. I may watch more of the video at home.
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posted
I saw this when someone posted it about a year and a bit ago. I thought it was an extremely interesting theory but just that, a theory; worth going "hmmm" over but not worth staking my reputation on.
(Not that I have a reputation)
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posted
Uh, yeah. Same here. I thought it was cool, but it is just a theory. I mean, is it technically even a theory? Shouldn't it be more like a hypothesis? It doesn't seem quite as concrete as the theory of reletivity.
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posted
It's a very real theory. Not the only one out there, but a lot of work is being devoted to it.
I suggest reading The Elegant Universe, the book the series was based on. I was actually disappointed in how little of the book the Nova series actually covered. The book is great, though, even for science dummies like me.
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posted
On a related note, if you liked the Nova series, I think you'd also get a kick out of What the Bleep Do We Know?, which is currently in theaters. It's a documentary of sorts - kind of quantum-physics-meets-new-age-wackos.
quote:Why do we need to combine the laws of gravity with laws that govern subatomic particles?
Because they're currently incompatible. General relativity, which we consider to be rather accurate, doesn't jive with quantum physics. There is no way that both theories, as we understand them today, can be totally true.
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I think I will read it too. The NOVA special was hosted by the author of the book, and it was very visual. It helped me understand basic principles, like gravity, better.
What the special is accomplishing for me is it makes physics more dynamic, interesting, and puts it into historical context. I think it is a great high-school or middle-school movie.
Now that I am sparked, I want to read it.
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posted
I might note that subatomic physics (my field, so I'm entitled to diss it) has long since reached the point where it is totally and absolutely useless. And, incidentally, the last time it was useful for anything was 1945 and not very pleasant.
This being so, there really is no answer to questions of the form "Why do we need to" other than "Physicists think this is cool, and besides, there's that trip to Stockholm."
You might more sensibly ask "Why do physicists think this is cool?" There are at least two reasons : First, the history of our field, as personified by our heroes, points that way. Maxwell unified the previously separate fields of electricity and magnetism. Quark theory explained the 'particle zoo' of the 50s in terms of a very few elementary constituents. Electroweak theory explained how Maxwell's work is a special case of a larger theory - this, in fact, is the canonical example of a unification, because it's just so neat. It is really a pity that you need three or four years of quantum mechanics and field theory to appreciate just how cool the equations are. The Standard Model, in turn, more-or-less unifies strong and electroweak theory, though not as nicely.
Second, there is elegance. It is really quite difficult to explain to a non-hard-science type how important this is; the best I can do is that a really neat explanation is sort of like looking at a naked woman. Wow, curves! It appeals on a level considerably below the conscious, a purely aesthetic appreciation. Being able to derive two apparently separate phenomena from one set of equations has that sort of appeal.
Another question you might reasonably ask is, "Why do governments fund this sort of thing? After all, I get no support for my insane hobbies." The answer is, it's a hoax. They think they're going to get more and better nukes, or mousetraps, or something. A senior scientist (whose name I don't at the moment recall) tells the story of testifying in front of a Senate committee on funding the SSC. "Will this machine give us a better understanding of God?" And the scientist thinks of explaining that he's an atheist, thinks of explaining the meaninglessness of looking for God in a set of equations, thinks of snappishly replying "I have never seen the need for that hypothesis"... And then recalls that he needs the money, takes a deep breath, and replies "Very possibly, Senator."
There are, of course, spinoffs. Particle physics drives research in superconductors (which we need for magnets) and in supercomputers and distributed computing (which we need for simulations and for analysing the torrent of data from modern detectors, respectively.) Similarly, very pure crystals, very sensitive detectors with radiation-hardened and fast electronics, signal-to-noise filters and algorithms, the list incidental stuff we work on is long.
And, of course, you never know. The governments might be right; a better mousetrap might well emerge from our supercolliders. After all, there was a time when nuclear physics was the most uselessly esoteric field imaginable.
[ January 05, 2005, 02:27 PM: Message edited by: King of Men ]
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quote:Because they're currently incompatible. General relativity, which we consider to be rather accurate, doesn't jive with quantum physics. There is no way that both theories, as we understand them today, can be totally true.
I guess I am showing my ignorance. Why can't they both be true.
The special showed a stop light with both a red light and a green light on at the same time. If we move from the example of a traffic light to include all city transportation, then the laws the govern automobiles need to be different then the laws governing subways. Different laws applied to different forms of transportation.
Since gravity and EM are two different types of energy, why is it so wrong to have different laws? If gravity is so weak, then couldn't the EM laws overpower it without breaking apart anything?
obviously I am not a physics major and accept I am showing my ignorance, but until I saw parts of the special, I didn't see the dichotomy.
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KoM -- except physics is one of those wonderful fields where every now and then the successive refinement of a totally useless idea results in a totally useful (tm) idea.
Witness electricity; for the longest time, electricity was but a curiousity. We find it rather useful nowadays .
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posted
It's not just an effort to combine the forces of gravity, electrmagnetism and strong ans weak atomic forces; it's an effort to combine two types of physics that we currently use. The math we use for subatomic (quantum) physics doesn't work on a huge, astrophysics level (general relativity) and vice versa.
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posted
fugu, the stupid browser took my attempt at starting a new paragraph as the signal to submit the post. It is rather longer now.
Gravity is weak at human scales, true, but becomes much stronger at sufficiently small scales - much smaller than we can currently probe with particle accelerators. That is where the theories clash, too. There's no contradiction on the everyday level of atomic nuclei.
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posted
I like to think that people just want to find truth (though the reason the search for truth gets funded may be more cynical than that.) Everything we have observed up until quantum physics told us that everything in reality is in agreement with itself. Relativity and quantum mechanics contradict each other. Weird stuff is going on at quantum level that doesn't make sense to us.
I totally understand the human need to tie it all together in a neat package. It is what we are used to getting in all other scientific study, a long and glorious tradition.
The fact is, we have no clue what gravity is. Superstring theory provides a possible answer.
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posted
I can vouch that The Elegant Universe is a great book. It's because of that book that I understand what relativity is and, more importantly, why it seems to work. Unfortunately, I havn't gotten around to *finishing* it, since I got distracted by a number of other things, and Calabi-Yau (sp?) multidimensional shapes broke my head for a few weeks.
There are two main problems with the book: (1) It gets me excited about science, which is a bad thing--I'm bad at math and even worse in a lab environment, and (2) It makes me want to tell my friends about "the cool thing I read in this book..." at which point they look at me like I'm on LSD. Especially my girlfriend. Posts: 903 | Registered: May 2003
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posted
Someone should point out that semiconductors (like your processor and memory) and laser technology both post date 1945 and are significantly useful.
posted
Also, cheap superconductors that don't need to be cooled down would lead to cheaper, lighter wires, no more fire hazards for Christmas lights, less electrical fires, cheaper electric biils (less resistance (but there's still impedance) to overcome = lower power needed = cheaper electric bill). It would revolutionize our current (no pun intended) system.
PS Some businesses have hinted that they have come up with an ultra-conductor. It's a cheap conductor whose resistance is not as low as the superconductor, but pretty darn low. They are keeping it under wraps until development is finished (i.e. they have found a way to maximize their profit from it without pissing people off).
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posted
Neither semiconductors nor superconductors were spinoffs from particle physics, though our need for fast, radiation-hardened electronics is what is driving Moore's law - according to our propaganda departments, anyway. Lasers likewise. While all these things rely on a good understanding of quantum mechanics, particle physics doesn't use classical QM per se - it's all relativistic field theory, a rather different subject.
Fusion has similar objections, considered as a spinoff from particle physics : Short of a really paradigmatic breakthrough allowing us to manipulate the strength of the electromagnetic field, or something, advances in our understanding of the basic forces just doesn't help very much with fusion. Modern HEP is increasing the energies at which we understand how the forces work; but fusion occurs usefully at energies where this has been understood for decades already. The problem is really one of engineering : We need magnetic field sufficiently strong to contain the vast temperatures involved.
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quote:King of Men wrote:Neither semiconductors nor superconductors were spinoffs from particle physics
But doesn't your previous statement imply that superconductors are a spinoff?
quote:King of Men wrote:There are, of course, spinoffs. Particle physics drives research in superconductors (which we need for magnets) and in supercomputers and distributed computing (which we need for simulations and for analysing the torrent of data from modern detectors, respectively.) Similarly, very pure crystals, very sensitive detectors with radiation-hardened and fast electronics, signal-to-noise filters and algorithms, the list incidental stuff we work on is long.
This really seems like you're contradicting yourself.
quote:Neither semiconductors nor superconductors were spinoffs from particle physics, though our need for fast, radiation-hardened electronics is what is driving Moore's law - according to our propaganda departments, anyway.
I'm a little confused as to what Moore's law has to do with the discussion.
For those of you who aren't familiar with Moore's Law, it's not really a law so much as an observation made by Gordon Moore that the number of transistors on an integrated circuit tends to double about every 18 to 24 months.
As far as I can tell, the need for rad-hard electronics has very little to do with increasing IC transistor density, which seems to be much more driven by consumer demand than anything else.
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quote:For those of you who aren't familiar with Moore's Law, it's not really a law so much as an observation made by Gordon Moore that the number of transistors on an integrated circuit tends to double about every 18 to 24 months.
That's because they have a gestation time twice that of a human.
Um. I've been following the Artificial Womb thread too closely.
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quote:For those of you who aren't familiar with Moore's Law, it's not really a law so much as an observation made by Gordon Moore that the number of transistors on an integrated circuit tends to double about every 18 to 24 months.
It was originally 12 months, but then chip technology had a hiccup, and it was changed to 18 months with Moore's blessing.
http://en.wikipedia.org/wiki/Moore%27s_Law (why won't the UBB code allow me to post this as a link with different words, yet I can do that with other links - anyone know?)
posted
I should express myself more clearly. The original research into semiconductors, leading to the transistor in 1948, was not a spinoff of HEP. The superconductor research leading to BCR theory in the 1960s was not a spinoff of HEP, though quantum mechanics and quantum field theory were not quite so strongly separated then as they are now. However, current research into superconductors is partly driven by HEP's need for ever bigger and better magnets - to get higher energies in circular colliders, you can up the magnet strength or increase the radius. Since the latter involves digging huge, expensive tunnels, magnets are preferred.
PC chips don't need to be rad-hard, certainly, but they do need to be fast. I should not have put the two together like that to give the impression that rad-hard-ness is driving computer chip research. HEP does need ever-faster computers to deal with recording, storing, and analysing the torrents of data coming from colliders, but only the components involved in the recording part need to be radiation-hard. As a matter of interest, the LHC, when it begins running, is expected to produce data at the rate of many GB per second.
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