The problem is, there isn't a lot of reason to believe that these scenarios ought to be true; they are highly speculative (even relative to string theory as a whole!).
Actually there is a good, theoretical, reason to think that these "Large Extra Dimension" (LED) scenarios might be correct (though I'll only believe it if we get data to back it up). If LEDs do exist they can solve the problem that the Standard Model of particle physics has explaining the huge difference in energy scales between the Planck scale (10^16 GeV) and the electroweak scale (10^2 GeV).
If LEDs exist then gravity might become a lot stronger above the ~TeV energy scale i.e. the Planck scale is actually ~10^3-4 GeV and not 10^16 GeV and a lower energy scales we are fooled into thinking gravity is a lot weaker simply because we can't see these extra dimensions where it spends a lot of its time.
The problem that LEDs have is in explaining proton decay. It is very likely that protons do in fact decay (this is linked to the fact that we only see protons and no anti-protons in the Universe) but with an incredibly long lifetime caused by the very high energy of the Planck scale. If you lower this energy to a few TeV you either end up with rapidly decaying protons (bad!) or having to put a conserved symmetry in which prevents all proton decay (also bad!).
So LEDs are an interesting theory which could solve some real problems with existing theory at the cost of introducing some new problems of their own. As a result I think Supersymmetry (which solves the problem which LEDs answer as well as the missing dark matter problem) is a better bet but I'll only believe it if we see it! Unfortunately from an experimentalists point of view LEDs would be a far more interesting discovery since it would mean we could start doing quantum gravity experimentally before the theorists have figured it all out....but not knowing exactly what you'll find is part of the fun of physics!
Actually depending on how strict your definition of solar is current nuclear power could be considered as such. If you allow solar to mean "from a star" and not just "sol" (which is not unreasonable since we talk of "solar systems" around other stars now) then fission reactors are actually using "fossilized" solar powered.
Fission reactors, our only current form of nuclear power, split uranium nuclei into smaller fragments and thereby release energy. However, to form the uranium atom in the first place from smaller constituents therefore required energy. This energy is thought to have come from a supernova ~6 billion years ago, predating the formation of the solar system. Thus current reactors are, by some (possibly warped!) definition, still using fossilized "solar" power. The same can also be said of geothermal which relies mainly on natural decay of nuclei formed by the same supernova.
Only if we ever get fusion reactors working then we really say that we are no longer reliant on solar based power...and that's because we will have made our own mini-sun.
Seriously, some putz at the local pub insisted the Pint glasses there were only 14 fluid ounces. Having a few of same at home I whipped out my trusty graduated cylinder and measured the volume with great precision. The result was close to 16.5 fluid ounces. I keep waiting for an opportunity to make a $100 bet
Hey will you take the same bet if there is some "putz" who insists the pint glass is 20 fl. oz? You don't mind visiting Canada or the UK do you?
I strongly disagree with this. Universities are supposed to uphold the best principles of academic freedom of speech. You average boss is not. While the comments in the blog are not exactly in the best principles of academic freedom of speech the university should be looking at the bigger picture. After this event students there are certainly not going to feel that they have much free speech are they?
If they objected to it so much they should have had a quiet word with the student and discussed the issue like adults, something which seems to be increasingly rare in modern society. Instead they appear to have run straight to their rule book and came up with the harshest punishment they could short of dropping him outright. Perhaps not the most sensible thing to do if you are so concerned with projecting a good image of your institute. As the saying goes "actions speak louder than words".
I think you are getting a little confused here between the Bible and the Koran. Christians, in general, believe that the bible was written by men who were inspired by God i.e. God revealed things to them which they then wrote down in their own words. This is different from my understanding of the Koran (and my apologies to any muslims here if I have got it wrong) where it is believed that Allah wrote it through the authors i.e. it is literally the direct word of god.
This is why taking the bible literally is generally not a good thing to do. You need to remember that there is no way that someone who's idea of a Big Bang is when the village cow farts and who thinks that a quark is the sound made by a constipated duck is going to be able to describe the wonder and magnificence of the Big Bang model of creation with modern scientific accuracy. Which, of course, is sort of the whole point because if Genesis had started talking about quark-gluon plasmas, matter-antimatter asymmetry and baryon number violation do you really think it would have helped people understand?
As a christian and a scientist, to me the wonder of Genesis is that, for the most part, the order of events agrees with current scientific understanding: first thing created was light, creatures envolved in the water before land, humans were the last to arrive etc. It's almost as if the author had our modern scientific understanding explained to him which he then wrote down in a way that he, and his contemporaries, could understand.....which kind of makes you think since it was written thousands of year ago!
As a European (British) scientist who worked in the US for several years and then moved to Canada (though more because of the anti-foreign sentiment than anti-scientist) I have to say that there is a HUGE difference between objections to science in Canada and Europe than in the US.
Here in Canada as well as Europe the objections to science are usually rational concerns about what science might be capable of doing if it goes wrong. These are usually founded on ignorance of the subject or distrust of explanations e.g. you can tell people that a nuclear fusion reactor is safe but they remember Chernobyl so they don't believe you and don't know enough physics to understand the huge difference between them.
This is understandable human behaviour. You can at least address the problem by education, admitting it when we do screw up and engaging people in an hoenst scientific debate. Their concerns might be (sometimes) founded on ignorance but, with some exceptions, it is a rational point of view.
In the US the situation is very different. There you get people who are fully aware of the science and choose to reject it. It is very hard to engage such people in a debate because they have a completely closed mind. They will disbelieve anything you tell them because it does not fit into their own view of the world. This is a completely irrational position which they try to defend by enshrouding it in scientific-sounding jiberish. No amount of rational debate or education will change their minds because they will just choose to disbelieve anything you say.
Why would the Autons, the Rift, the Slovenes, the gas creatures, and Rose's home all be in Cardiff? I'd never heard of this place before; the coincidence strains credulity.
The rift and the gas creatures were related. The Slovenes and Rose's home were in London (hope you have heard of that city - if not welcome to Earth:-) NOT Cardiff. That big dish thing of the Autons was actually the London Eye. One Slovene later went to Cardiff because of the rift.
The reason you might be confused is that the series was filmed in Cardiff presumably because it was cheaper. The one thing I did notice was an abnormally high number of welsh accents amongst the extras.
Since quarks are spin-1/2 particles they have to be rotated through 720 degrees to get back to their original state and not 360 degress like normal objects. So these pics are a long way from what an actual quark might look like (not to mention they label the W boson as neutral when it is actually charged!).
So given that several people have come out in favour of the US retaining control given that they invented the Internet in the first place, do these same people think that Britain should have control over what stamps countries are allowed to use in the postal services since it invented the stamp?
Yes I know that is a completely insane idea...but so is one country trying to control all IP addresses and names.
Hmmm....well as a "house guest" (and member of the rest of the world) if thats what you think you really want, lets build our own house and see how you like living in your empty dwelling listening to the party next door.
Let's project where it will be in five years: 99.999% of the mass of the universe (100,000 times as much mass as the bits we see...
You clearly don't understand the difference between dark matter and dark energy. Dark matter hass mass, dark energy is gravitationally repulsive and so clearly is not mass (though it is energy). Rotational curves of galaxies add further support for the idea of dark matter. The "dark energy" is not at all understood. It might be something real or it might be the effect of mass we can't observe.
They still will have no particular properties, other than whatever it takes to rescue somebody's pet theory.
You really don't have any clue about the scientific process do you? If you can come up with a theory that agress with the experimental data better than the Big Bang then please, share it with us. So far NOBODY has been able to. Your assumption that the "Universe has to have a blackbody temperature" is only valid if you assume that the Universe is causally connected. If it were not then different parts would have different temperatures. You also have to explain the fluctuations at the level observed which were consistent with Big Bang predictions - though there was no requirement that they be if the Big Bang was wrong.
You might not like the Big Bang model, and chances are, at least some of the details are probably wrong as we understand them now. However it is the best fit for the current data. If you think you have a better model then it is your job to show how it is more consistent with data than the Big Bang. Nobody is going to reject the Big Bang just because you say so! In fact the conjecturing that you seem to so vehemently oppose is part of the process of finding better models. One person proposes an idea and then either gets shot down by data, confimed by data or put on one side until there is some data to confirm or deny it.
On the last point, I can't remember the exact numbers but it's not as simple as "light particle = hot dark matter" / "heavy particle = cold dark matter".
You are correct. It depends strongly on the interaction cross-section which is why the neutrino gives hot dark matter: it effectively stops interacting (and so drops out of thermal equilibrium) well above its mass threshold and so dissociates from the rest of matter when its KE is a lot greater than its mass energy.
What I don't understand is how such a light particle can remain in thermal equilibrium (to give cold dark matter) whilst still having a very low interaction cross section. If it has a strong cross-section then we should produce it (and hence presumably detect it or at least notice its absence) with current accelerators. However I'm not a cosmologist (or theorist!) so there must be something I'm missing (an additional cooling mechanism?). I'll have to take a look at the axion paper.
...this paper seems to completely ignore the laboratory work that has been done. In particular the D0 experiment at the Tevatron has already set world leading exclusion limits on ADD extra-dimensions (I presented them at a conference this summer!). Below an energy scale of ~1 TeV, depending on the precise model you use, they are effectively ruled out up to a lot greater than n=3 extra dimensions.
The other major problem seems to be the tiny mass of the dark matter particle. If its mass is so small why have we not produced it in accelerators yet? You might think that it has escaped notice but then the neutrino (which has a mass so close to zero we can't measure it) is easily observed. Peraps it is possible to concoct some scheme where this particle only couples gravitationally but then wouldn't it form "hot" dark matter (which WMAP has effectively rules out)?
Hmmm....I need to find a friendly particle theorist to ask:-)
My money is on the folks who say global warming is happening because they have quantifiable data to back their claims up...... Seriously. All the investors need to put down the crack pipes and realize that they are indirectly responsible for a lot of really rotten things. Don't just bury your head in the sand. Accept the fucking responsibility.
I agree that there is a mounting body of evidence that global warming is indeed a reality. However there is far, far less evidence that green house gas emission is the cause. There is ample evidence of extreme temperature fluctuations in the past thousands to millions of years before the industrial revolution. Some of these cycles are linked to known effects (e.g. precession of the earth's axis or rotation) and others are not understood.
The reason I would argue to reduce greenhouse gas emissions that we simply do not know what the effect will be. Perhaps natural climate change will greatly outweigh the greenhouse effect and perhaps not. Geological evidence suggests we are actually entering an ice age so greenhouse gas emission might help prevent or postpone this, or it might make things a lot worse. Essentially what it boils down to is that we are performing a large, uncontrolled experiment with our environment and that, in my opinion is a stupid thing to do. Unfortunately this is a far weaker argument than being able to say "if you don't cut emissions by X sea levels will rise by Y".
Google did not give me what I wanted since it assumed US dollars and I'm in Canada forgivable, perhaps since the URL you gave was google.com. However google.ca makes the same assumption which is just plain dumb!
The one suggested in the original post took the other approach and included every conversion rate under the sun: want to convert Solomon Island dollars to Egyptian pounts anyone?
I think I'll stick to one with the pull down menus to specify currencies precisely since I don't always know the 3 letter currency code.
That would be fine, except that every single one of these press releases is filled with wild speculation
That's true but the press release is clear about it. It basically says "we have no clue what is happening but here are some possibilities". This is a press release after all and hardly a scientific paper. That being said I also get really irritated by the pontificating idiots they sometimes get to explain things who so often gloss over (or ignore) the fact that what they are saying is speculation and not generally accepted fact.
Never mind trotting out black holes, billion-solar-mass black holes, "dark matter" (imagined to constitute 90% of the mass of the universe), "dark energy" (part of it? supposed to repel matter), the "Great Attractor", galactic lensing, "magnetic reconnection", WIMPs, MACHOs, the Big Bang, Inflation, zero-point energy...
It is interesting that we should be talking about wild speculation here because actually dark matter is thought to make up ~23% of the universe and dark energy ~76% (1% being "normal" baryonic, luminous matter). As for the rest gravitational lensing was predicted by Einstein's general relativity before it was observed, zero point energy is a consequence of quantum mechanics (a theory tested to an unprecedented level of precision) and WIMPs are simply candidates for dark matter.
Of course no single experiment, or even a dozen, can do any such thing, and Big Bang is looking iffier every month.
The Big Bang, contrary to your claim, keeps getting more and more experimental backing. Super novae studies and the cosmic microwave background are consistent. Recently the CMB fluctuations lend it further support.
I don't know about this film but I have seen a previous IMAX 3D film about cosmology and evolution (that other big scientific conspirancy:-)
Like you I was extremely sceptical about whether the it would work having not been impressed by 3D TV and the like. However, the huge screen of the IMAX does make the 3D really work! It was incredible you had to duck fusing nuclei in a supernova, watch evoling animals dancing over the heads of the people in front etc. The huge screen gives the picture an enormous depth so the 3D works very well. Of course this was with relatively basic computer graphics so I've no idea how more complex scenes would work but I'd be interested in seeing when it comes out.
The fact is, it's *the biggest machine in the world*, bar none. There's almost 30 miles of completely automated track, more motors and linear accelerators than you can shake a stick at.
Well, being a particle physicist I've got a pretty big stick to shake. The biggest machine in the world was actually the LEP accelerator at CERN, shortly to be replaced by the LHC also at CERN. In terms of accelerators I doubt a baggage handling system will reach quite the same energies although that would explain the condition of my bags when handed back on occasion.
Now it is true that the LEP ring is only 27km in circumference. However it truly is a single machine: your bagage handling system consists of lots of machines acting under a single controller. If one train breaks down it might block the tunnel it is in but it does not stop all the other machines from working (although may be it does and that is why they need to replace it?). If one part of LEP breaks down then the accelerator will not work until it is fixed or mitigated by some other means.
Finally if you are not convinced by that argument then you would also have to include all new automated mass transit systems as single machines e.g. Jubliee, victoria and Dockland light railway lines (maybe more by now?) of the London tube system. These total to over 30 miles and so would be a bigger machine.
Reading the original article (always a bad move) it talked about blocking dodgy looking web requests which, I'm guessing, took up a significant fraction of the server's resources. In such a case I'd go ahead and block. You might loose some potential valid users but that is a lot less than loosing everyone if your server clogs up.
However I'd suggest a dynamic blocking as the best means to do i.e. a machine generated list. Have a server outside the firewall examine incoming requests and block IP ranges where significant numbers of dubious requests are coming from. If the number of dubious requests falls below a certain rate then the IP range is unblocked.
This is a lot better than a permanent ban because you can't be accused of implementing a political agenda of your own and it rewards ISPs/Companies/Countries that eventually clean up their network space. Of course it does mean that you have to be able to define in terms a computer will understand what a "dodgy" request is.
Atomic decay is governed by a force in this case the electromagnetic, and thus the first law does not apply.
Firstly pion decay is not atomic decay - no nucleus is involved. Secondly you don't understand what an external force is, which you really should do if you do have a physics degree. This force is internal to the system and thus Newton's first law does apply as long as you consider the entire system i.e. both photons.
The idea of momentum as a 4-vector only makes sense when motivated by the invariance of the velocity of light with respect to comoving observers.
I'm sorry but this is absolutely wrong. Momentum is fundamentally a 4-vector. For "everyday" energy levels i.e. processes that typical people encounter in an average day an excellent approximation is Newton's 3-momentum. The motivation for using 4-vector momentum is that you have to at high energy levels (bodies with K.E. > ~10% of the rest mass energy) otherwise you get experimental results inconsistent with conservation of momentum. It was historically discovered through the path you describe but there is no requirement that be the case. Had Einstein not been born accurate measurements of high energy electron momenta would also lead to Special Relativity. Einstein's genius was that with a tiny amount of data he lept to the right conclusions. But realtivity is way more important than just talking about the speed of light in two intertial frames.
In the sense that relativity is not a quantum theory...
Depends on your definition of "classical" physics. The one I use, and I believe is the most common one, is physics based on Newtonian mechanics. SR is non-Newtonian and therefore non-classical. It is possible that my definition is not as common as I think but you'll have to excuse me if I don't take your word for it.
Light exhibits self interference which no reasonable definition of the word particle as used in everyday experience allows.
That is where quantum physics comes in. Light is indeed made of "particles" or quanta called photons. These do not behave like ordinary everyday particles but nevertheless are referred to as particles because of their localised nature.
Given that few people have ready access to equipment that measures time or distance to better than six significant figures the relativistic correction is indistinguishable from measurement error.
I'm glad you agree, that is PRECISELY my point! They are approximations. I'll grant you they are very good approximations (which is why they held so long) but approximations nonetheless.
Which leads to my point that Newton was correct for what he was capable of knowing.
What exactly does this mean? He was "correct" because he didn't know he was wrong? So does that mean the only time you are ever wrong is when you are capable of knowing you are? If so perhaps you'd better brush up on the meaning of the word "wrong".
...are consistent with a universe in which infinite velocities are possible and the speed of light depends on the motion of the observer. There was no reason for Newton to suppose that either of those things weren't true.
Neither was there any reason to suppose that they were true. He certainly had no experimental evidence to that effect. That was a mistake, an easily forgivable one but still a mistake....and mistakes lead to being wrong!
Newton's formulas, which are to be distinguished from his laws...
Why exactly? What you are saying here is that if you take Newton's words, redefine the physical quantities to the SR expressions and keep calling them the same thing then he is still correct. i.e. if we redefine the bits that Newton got wrong the rest still works! All you have done is said that instead of getting the laws wrong Newton got the definitions of momentum, acceleration and force wrong.
This is pure semantics either I redefine 'F' and 'p' to keep F=dp/dt or I keep 'F' an
Newton's Laws are perfectly fine, the first: an object in motion will continue in motion until acted upon by an outside force is perfectly consistent with General (and of course Special) Relativity, although it's very difficult to talk about acceleration in Special Relativity (see Newton's Second Law)
Actually this is not consistent with special relativity. Special relativity allows me to convert mass into energy so suppose I start with a neutral pion. This can be travelling at a constant velocity when it decays into two photons. Suddenly I have now have no mass and my speed is that of light...and no external forces acted. Ooops!
Newton's Second Law: that the change in motion is proportional its change in momentum
First that is NOT Newton's second law since Newton actually defined momentum as "motion" and the above is just that definition - no physics involved. The correct law is:
The rate of change of momentum of a body is proportional to the external force applied.
This is only correct if you use the 4-vector definitions for force and momentum and not Newton's. Thus, the law as Newton wrote it is wrong.
Newton's Third law, Every reaction is met by an equal and opposite reaction is simply conservation of energy and is not violated in any classical theory, of which relativity both General and Special are.
Ok lets fix this one...first a minor point: relativity is NOT classical physics. Now consider trying to stop a relativistic cricket ball (or baseball for you Canadians out there). The distance moved by the ball while you stop it will vary depending on whether you look at it from the balls point of view or the cricket pitch's point of view. Since, as you point out energy is force times distance the ball and the catcher will both observe different forces. Thus NIII is not correct either...unless you use 4-vector definitions for force.
What Newton was wrong about (and it's not really fair to call him wrong since......)....and the nature of light as a particle.
Oh boy this is so utterly wrong it is even funny! One of Newton's most amazing ideas that turned out to be CORRECT was the particle nature of light, although the lacked the means to prove it. What is so ironic about your statement is that Einstein was the one who showed that light behaved as a particle in the same year as his relativity paper. Thus the one time you would be correct in saying that Einstein showed Newton to be correct you instead say he is wrong!
As for calling Newton wrong I think you have got confused between cause and effect. Newton was wrong BECAUSE he lacked the means to discover relativity. This does not make him any less wrong. His achievements were amazing given his resources and the previous state of physics and no amount of time will alter that...but he is still wrong! Even at everyday energies Newton's laws are only approximatations and are not correct. However they are such good approximations and so much simpler to understand that we still teach them to school kids. Newton was an amazing genius, arguably even more so that Einstein: he also made huge contributions to maths [~invented calculus] and anti-counterfeiting measures [as master of the royal mint]. His contributions to physics were incredible, but still in the end his laws were proven wrong just, as I am sure, we will find a lot of our current understanding will not quite be correct in a hundred years from now.
Slashdot Mirror
Actually there is a good, theoretical, reason to think that these "Large Extra Dimension" (LED) scenarios might be correct (though I'll only believe it if we get data to back it up). If LEDs do exist they can solve the problem that the Standard Model of particle physics has explaining the huge difference in energy scales between the Planck scale (10^16 GeV) and the electroweak scale (10^2 GeV).
If LEDs exist then gravity might become a lot stronger above the ~TeV energy scale i.e. the Planck scale is actually ~10^3-4 GeV and not 10^16 GeV and a lower energy scales we are fooled into thinking gravity is a lot weaker simply because we can't see these extra dimensions where it spends a lot of its time.
The problem that LEDs have is in explaining proton decay. It is very likely that protons do in fact decay (this is linked to the fact that we only see protons and no anti-protons in the Universe) but with an incredibly long lifetime caused by the very high energy of the Planck scale. If you lower this energy to a few TeV you either end up with rapidly decaying protons (bad!) or having to put a conserved symmetry in which prevents all proton decay (also bad!).
So LEDs are an interesting theory which could solve some real problems with existing theory at the cost of introducing some new problems of their own. As a result I think Supersymmetry (which solves the problem which LEDs answer as well as the missing dark matter problem) is a better bet but I'll only believe it if we see it! Unfortunately from an experimentalists point of view LEDs would be a far more interesting discovery since it would mean we could start doing quantum gravity experimentally before the theorists have figured it all out....but not knowing exactly what you'll find is part of the fun of physics!
Fission reactors, our only current form of nuclear power, split uranium nuclei into smaller fragments and thereby release energy. However, to form the uranium atom in the first place from smaller constituents therefore required energy. This energy is thought to have come from a supernova ~6 billion years ago, predating the formation of the solar system. Thus current reactors are, by some (possibly warped!) definition, still using fossilized "solar" power. The same can also be said of geothermal which relies mainly on natural decay of nuclei formed by the same supernova.
Only if we ever get fusion reactors working then we really say that we are no longer reliant on solar based power...and that's because we will have made our own mini-sun.
Hey will you take the same bet if there is some "putz" who insists the pint glass is 20 fl. oz? You don't mind visiting Canada or the UK do you?
Well when using Windows XP I often pray that things will work...
I strongly disagree with this. Universities are supposed to uphold the best principles of academic freedom of speech. You average boss is not. While the comments in the blog are not exactly in the best principles of academic freedom of speech the university should be looking at the bigger picture. After this event students there are certainly not going to feel that they have much free speech are they?
If they objected to it so much they should have had a quiet word with the student and discussed the issue like adults, something which seems to be increasingly rare in modern society. Instead they appear to have run straight to their rule book and came up with the harshest punishment they could short of dropping him outright. Perhaps not the most sensible thing to do if you are so concerned with projecting a good image of your institute. As the saying goes "actions speak louder than words".
This is why taking the bible literally is generally not a good thing to do. You need to remember that there is no way that someone who's idea of a Big Bang is when the village cow farts and who thinks that a quark is the sound made by a constipated duck is going to be able to describe the wonder and magnificence of the Big Bang model of creation with modern scientific accuracy. Which, of course, is sort of the whole point because if Genesis had started talking about quark-gluon plasmas, matter-antimatter asymmetry and baryon number violation do you really think it would have helped people understand?
As a christian and a scientist, to me the wonder of Genesis is that, for the most part, the order of events agrees with current scientific understanding: first thing created was light, creatures envolved in the water before land, humans were the last to arrive etc. It's almost as if the author had our modern scientific understanding explained to him which he then wrote down in a way that he, and his contemporaries, could understand.....which kind of makes you think since it was written thousands of year ago!
Here in Canada as well as Europe the objections to science are usually rational concerns about what science might be capable of doing if it goes wrong. These are usually founded on ignorance of the subject or distrust of explanations e.g. you can tell people that a nuclear fusion reactor is safe but they remember Chernobyl so they don't believe you and don't know enough physics to understand the huge difference between them.
This is understandable human behaviour. You can at least address the problem by education, admitting it when we do screw up and engaging people in an hoenst scientific debate. Their concerns might be (sometimes) founded on ignorance but, with some exceptions, it is a rational point of view.
In the US the situation is very different. There you get people who are fully aware of the science and choose to reject it. It is very hard to engage such people in a debate because they have a completely closed mind. They will disbelieve anything you tell them because it does not fit into their own view of the world. This is a completely irrational position which they try to defend by enshrouding it in scientific-sounding jiberish. No amount of rational debate or education will change their minds because they will just choose to disbelieve anything you say.
...when pigs can fly.
No really, I will!
The rift and the gas creatures were related. The Slovenes and Rose's home were in London (hope you have heard of that city - if not welcome to Earth :-) NOT Cardiff. That big dish thing of the Autons was actually the London Eye. One Slovene later went to Cardiff because of the rift.
The reason you might be confused is that the series was filmed in Cardiff presumably because it was cheaper. The one thing I did notice was an abnormally high number of welsh accents amongst the extras.
Since quarks are spin-1/2 particles they have to be rotated through 720 degrees to get back to their original state and not 360 degress like normal objects. So these pics are a long way from what an actual quark might look like (not to mention they label the W boson as neutral when it is actually charged!).
So given that several people have come out in favour of the US retaining control given that they invented the Internet in the first place, do these same people think that Britain should have control over what stamps countries are allowed to use in the postal services since it invented the stamp? Yes I know that is a completely insane idea...but so is one country trying to control all IP addresses and names.
Hmmm....well as a "house guest" (and member of the rest of the world) if thats what you think you really want, lets build our own house and see how you like living in your empty dwelling listening to the party next door.
You clearly don't understand the difference between dark matter and dark energy. Dark matter hass mass, dark energy is gravitationally repulsive and so clearly is not mass (though it is energy). Rotational curves of galaxies add further support for the idea of dark matter. The "dark energy" is not at all understood. It might be something real or it might be the effect of mass we can't observe.
They still will have no particular properties, other than whatever it takes to rescue somebody's pet theory.
You really don't have any clue about the scientific process do you? If you can come up with a theory that agress with the experimental data better than the Big Bang then please, share it with us. So far NOBODY has been able to. Your assumption that the "Universe has to have a blackbody temperature" is only valid if you assume that the Universe is causally connected. If it were not then different parts would have different temperatures. You also have to explain the fluctuations at the level observed which were consistent with Big Bang predictions - though there was no requirement that they be if the Big Bang was wrong.
You might not like the Big Bang model, and chances are, at least some of the details are probably wrong as we understand them now. However it is the best fit for the current data. If you think you have a better model then it is your job to show how it is more consistent with data than the Big Bang. Nobody is going to reject the Big Bang just because you say so! In fact the conjecturing that you seem to so vehemently oppose is part of the process of finding better models. One person proposes an idea and then either gets shot down by data, confimed by data or put on one side until there is some data to confirm or deny it.
You are correct. It depends strongly on the interaction cross-section which is why the neutrino gives hot dark matter: it effectively stops interacting (and so drops out of thermal equilibrium) well above its mass threshold and so dissociates from the rest of matter when its KE is a lot greater than its mass energy.
What I don't understand is how such a light particle can remain in thermal equilibrium (to give cold dark matter) whilst still having a very low interaction cross section. If it has a strong cross-section then we should produce it (and hence presumably detect it or at least notice its absence) with current accelerators. However I'm not a cosmologist (or theorist!) so there must be something I'm missing (an additional cooling mechanism?). I'll have to take a look at the axion paper.
...this paper seems to completely ignore the laboratory work that has been done. In particular the D0 experiment at the Tevatron has already set world leading exclusion limits on ADD extra-dimensions (I presented them at a conference this summer!). Below an energy scale of ~1 TeV, depending on the precise model you use, they are effectively ruled out up to a lot greater than n=3 extra dimensions.
:-)
The other major problem seems to be the tiny mass of the dark matter particle. If its mass is so small why have we not produced it in accelerators yet? You might think that it has escaped notice but then the neutrino (which has a mass so close to zero we can't measure it) is easily observed. Peraps it is possible to concoct some scheme where this particle only couples gravitationally but then wouldn't it form "hot" dark matter (which WMAP has effectively rules out)?
Hmmm....I need to find a friendly particle theorist to ask
I agree that there is a mounting body of evidence that global warming is indeed a reality. However there is far, far less evidence that green house gas emission is the cause. There is ample evidence of extreme temperature fluctuations in the past thousands to millions of years before the industrial revolution. Some of these cycles are linked to known effects (e.g. precession of the earth's axis or rotation) and others are not understood.
The reason I would argue to reduce greenhouse gas emissions that we simply do not know what the effect will be. Perhaps natural climate change will greatly outweigh the greenhouse effect and perhaps not. Geological evidence suggests we are actually entering an ice age so greenhouse gas emission might help prevent or postpone this, or it might make things a lot worse. Essentially what it boils down to is that we are performing a large, uncontrolled experiment with our environment and that, in my opinion is a stupid thing to do. Unfortunately this is a far weaker argument than being able to say "if you don't cut emissions by X sea levels will rise by Y".
My point was not that you can't do it but simply that assuming dollars means US dollars is a stupid default for the Canadian google site!
Google did not give me what I wanted since it assumed US dollars and I'm in Canada forgivable, perhaps since the URL you gave was google.com. However google.ca makes the same assumption which is just plain dumb! The one suggested in the original post took the other approach and included every conversion rate under the sun: want to convert Solomon Island dollars to Egyptian pounts anyone? I think I'll stick to one with the pull down menus to specify currencies precisely since I don't always know the 3 letter currency code.
That's true but the press release is clear about it. It basically says "we have no clue what is happening but here are some possibilities". This is a press release after all and hardly a scientific paper. That being said I also get really irritated by the pontificating idiots they sometimes get to explain things who so often gloss over (or ignore) the fact that what they are saying is speculation and not generally accepted fact.
Never mind trotting out black holes, billion-solar-mass black holes, "dark matter" (imagined to constitute 90% of the mass of the universe), "dark energy" (part of it? supposed to repel matter), the "Great Attractor", galactic lensing, "magnetic reconnection", WIMPs, MACHOs, the Big Bang, Inflation, zero-point energy...
It is interesting that we should be talking about wild speculation here because actually dark matter is thought to make up ~23% of the universe and dark energy ~76% (1% being "normal" baryonic, luminous matter). As for the rest gravitational lensing was predicted by Einstein's general relativity before it was observed, zero point energy is a consequence of quantum mechanics (a theory tested to an unprecedented level of precision) and WIMPs are simply candidates for dark matter.
Of course no single experiment, or even a dozen, can do any such thing, and Big Bang is looking iffier every month.
The Big Bang, contrary to your claim, keeps getting more and more experimental backing. Super novae studies and the cosmic microwave background are consistent. Recently the CMB fluctuations lend it further support.
Like you I was extremely sceptical about whether the it would work having not been impressed by 3D TV and the like. However, the huge screen of the IMAX does make the 3D really work! It was incredible you had to duck fusing nuclei in a supernova, watch evoling animals dancing over the heads of the people in front etc. The huge screen gives the picture an enormous depth so the 3D works very well. Of course this was with relatively basic computer graphics so I've no idea how more complex scenes would work but I'd be interested in seeing when it comes out.
Well, being a particle physicist I've got a pretty big stick to shake. The biggest machine in the world was actually the LEP accelerator at CERN, shortly to be replaced by the LHC also at CERN. In terms of accelerators I doubt a baggage handling system will reach quite the same energies although that would explain the condition of my bags when handed back on occasion.
Now it is true that the LEP ring is only 27km in circumference. However it truly is a single machine: your bagage handling system consists of lots of machines acting under a single controller. If one train breaks down it might block the tunnel it is in but it does not stop all the other machines from working (although may be it does and that is why they need to replace it?). If one part of LEP breaks down then the accelerator will not work until it is fixed or mitigated by some other means.
Finally if you are not convinced by that argument then you would also have to include all new automated mass transit systems as single machines e.g. Jubliee, victoria and Dockland light railway lines (maybe more by now?) of the London tube system. These total to over 30 miles and so would be a bigger machine.
Reading the original article (always a bad move) it talked about blocking dodgy looking web requests which, I'm guessing, took up a significant fraction of the server's resources. In such a case I'd go ahead and block. You might loose some potential valid users but that is a lot less than loosing everyone if your server clogs up.
However I'd suggest a dynamic blocking as the best means to do i.e. a machine generated list. Have a server outside the firewall examine incoming requests and block IP ranges where significant numbers of dubious requests are coming from. If the number of dubious requests falls below a certain rate then the IP range is unblocked.
This is a lot better than a permanent ban because you can't be accused of implementing a political agenda of your own and it rewards ISPs/Companies/Countries that eventually clean up their network space. Of course it does mean that you have to be able to define in terms a computer will understand what a "dodgy" request is.
Firstly pion decay is not atomic decay - no nucleus is involved. Secondly you don't understand what an external force is, which you really should do if you do have a physics degree. This force is internal to the system and thus Newton's first law does apply as long as you consider the entire system i.e. both photons.
The idea of momentum as a 4-vector only makes sense when motivated by the invariance of the velocity of light with respect to comoving observers.
I'm sorry but this is absolutely wrong. Momentum is fundamentally a 4-vector. For "everyday" energy levels i.e. processes that typical people encounter in an average day an excellent approximation is Newton's 3-momentum. The motivation for using 4-vector momentum is that you have to at high energy levels (bodies with K.E. > ~10% of the rest mass energy) otherwise you get experimental results inconsistent with conservation of momentum. It was historically discovered through the path you describe but there is no requirement that be the case. Had Einstein not been born accurate measurements of high energy electron momenta would also lead to Special Relativity. Einstein's genius was that with a tiny amount of data he lept to the right conclusions. But realtivity is way more important than just talking about the speed of light in two intertial frames.
In the sense that relativity is not a quantum theory...
Depends on your definition of "classical" physics. The one I use, and I believe is the most common one, is physics based on Newtonian mechanics. SR is non-Newtonian and therefore non-classical. It is possible that my definition is not as common as I think but you'll have to excuse me if I don't take your word for it.
Light exhibits self interference which no reasonable definition of the word particle as used in everyday experience allows.
That is where quantum physics comes in. Light is indeed made of "particles" or quanta called photons. These do not behave like ordinary everyday particles but nevertheless are referred to as particles because of their localised nature.
Given that few people have ready access to equipment that measures time or distance to better than six significant figures the relativistic correction is indistinguishable from measurement error.
I'm glad you agree, that is PRECISELY my point! They are approximations. I'll grant you they are very good approximations (which is why they held so long) but approximations nonetheless.
Which leads to my point that Newton was correct for what he was capable of knowing.
What exactly does this mean? He was "correct" because he didn't know he was wrong? So does that mean the only time you are ever wrong is when you are capable of knowing you are? If so perhaps you'd better brush up on the meaning of the word "wrong".
Neither was there any reason to suppose that they were true. He certainly had no experimental evidence to that effect. That was a mistake, an easily forgivable one but still a mistake....and mistakes lead to being wrong!
Newton's formulas, which are to be distinguished from his laws...
Why exactly? What you are saying here is that if you take Newton's words, redefine the physical quantities to the SR expressions and keep calling them the same thing then he is still correct. i.e. if we redefine the bits that Newton got wrong the rest still works! All you have done is said that instead of getting the laws wrong Newton got the definitions of momentum, acceleration and force wrong.
This is pure semantics either I redefine 'F' and 'p' to keep F=dp/dt or I keep 'F' an
Actually this is not consistent with special relativity. Special relativity allows me to convert mass into energy so suppose I start with a neutral pion. This can be travelling at a constant velocity when it decays into two photons. Suddenly I have now have no mass and my speed is that of light...and no external forces acted. Ooops!
Newton's Second Law: that the change in motion is proportional its change in momentum
First that is NOT Newton's second law since Newton actually defined momentum as "motion" and the above is just that definition - no physics involved. The correct law is:
The rate of change of momentum of a body is proportional to the external force applied.
This is only correct if you use the 4-vector definitions for force and momentum and not Newton's. Thus, the law as Newton wrote it is wrong.
Newton's Third law, Every reaction is met by an equal and opposite reaction is simply conservation of energy and is not violated in any classical theory, of which relativity both General and Special are.
Ok lets fix this one...first a minor point: relativity is NOT classical physics. Now consider trying to stop a relativistic cricket ball (or baseball for you Canadians out there). The distance moved by the ball while you stop it will vary depending on whether you look at it from the balls point of view or the cricket pitch's point of view. Since, as you point out energy is force times distance the ball and the catcher will both observe different forces. Thus NIII is not correct either...unless you use 4-vector definitions for force.
What Newton was wrong about (and it's not really fair to call him wrong since ......)....and the nature of light as a particle.
Oh boy this is so utterly wrong it is even funny! One of Newton's most amazing ideas that turned out to be CORRECT was the particle nature of light, although the lacked the means to prove it. What is so ironic about your statement is that Einstein was the one who showed that light behaved as a particle in the same year as his relativity paper. Thus the one time you would be correct in saying that Einstein showed Newton to be correct you instead say he is wrong!
As for calling Newton wrong I think you have got confused between cause and effect. Newton was wrong BECAUSE he lacked the means to discover relativity. This does not make him any less wrong. His achievements were amazing given his resources and the previous state of physics and no amount of time will alter that...but he is still wrong! Even at everyday energies Newton's laws are only approximatations and are not correct. However they are such good approximations and so much simpler to understand that we still teach them to school kids. Newton was an amazing genius, arguably even more so that Einstein: he also made huge contributions to maths [~invented calculus] and anti-counterfeiting measures [as master of the royal mint]. His contributions to physics were incredible, but still in the end his laws were proven wrong just, as I am sure, we will find a lot of our current understanding will not quite be correct in a hundred years from now.