Severian

No - rusting is oxidization. The iron bonds with oxygen in the air to form rust. In a vacuum there is no oxygen, so no rust.

It is exactly the same ideas as we have already proven for the photon. All gravitons which mediate gravity, must be virtual by definition (just as the virtual photons mediate electromagetism). Also the graviton is its own antiparticle, just like the photon is its own antiparticle.

People keep talking about wave particle duality, but imho that is the wrong way to think of it. Despite the whole subject being called 'particle physics', we really need to get away from the idea that the fundamantal objects are point particles. We should think of them as fields instead. A field is a basically a set of numbers, one (or somethimes more) for each point in space. So a wave on the ocean can be thought of as a field, since the size of the wave varies from place to place, and changes in this magnitude make the wave appear to move. Light is just such a field (it is actually an electromagnetic field), and this is why it has wave like properties. The difficult thing to get your head round with Quantum Mechanics is that you cannot make a measurement of a field's properties without changing the field irreversibly. When I make a measurement the field changes in all of space instantaneously (this looks like it violates special relativity, but in fact it does not). If I try to measure the position of a field (that is, the value at the various space time points) the field 'collapses' into all being very very close to one point - the shape of the field basically becomes a very sharp spike at one point in space. This is what we think of as a particle, but really it is still a field - it just has a zero value for most of space, but is not even pointlike because we cannot measure position infinitely well (there will always be some error in our measurment). Left on its own, this very localised field will spread out in a wave like way and eventually will be spread out over a large volume of space again. But if we keep measuring its position (ie watch it) it will keep collapsing to a localised version and will look and behave like what we traditionally call a particle. In other words, there really is no particle-wave duality. The fundamental objects are always 'waves', and it is just that when they are very densly concentrated in one place they look like particles.

My 2c: don't do a PhD unless you are genuinely interested in the subject and will have fun while doing the PhD. Don't do it solely to get a research job in the area or if you want to make money. I think the money seems to tail off at a masters, so if you want to make money, do an MBA. Imagine this situation. You do a PhD for say 5 years, complete it, write up and have a successfull PhD exam, only to be told that through a technicality (you hadn't signed some form at matriculation or something) that you won't get the PhD. Would the 5 years have been a waste or was it still worth it. Only do the PhD if it would have been still worth it for you.

It is actually quite interesting. I am a bit confused though, as to why he can use the KG equation for the energy levels of electrons, which are obviously fermions and therfore obey the Dirac Equation, not the KG equation. This is probably something do do with the KG equation being the square of the Dirac equation, but it doesn't seem a very rigourous argument. I had to chuckle at his inability to write \nabla...

To answer the original question, most of these extra particles have no impact on our everyday lives, but they still need to be present in oder to have a consistant theory. Many are just different bound states of the same quarks used to build protons and neutrons, so if they weren't there we would have problems with the theory. It is more interesting to ask if we need the ones which are built from different quarks form the ones that build protons and neutrons. The quarks and neutrons are made up of 'up' and 'down' type quarks, which are in the same 'family' as the electron and its neutrino (which are leptons). But there are two additional families of quarks and leptons with exactly the same properties, only heavier. These are: Family 2: charm and strange quarks; muon and muon-neutrino Family 3: top and bottom quark; tau and tau-neutrino We don't yet know why there are 3 families, but there are many subtleties in particle physics which would be absent with only one family. For example CP-violation in its know form needs multiple families. Also, it looks like it is the large top quark mass which triggers electroweak symmetry breaking. So without the other 2 families, things would not look the same, and the hadrons made out of these families are necessarily there once the quarks are there.

Works now

It seems perfectly consistant to me. If you do things to a foetus/embryo/whatever that will make it turn into a disabled child, then you are harming the child through your actions. If you abort the foetus/embryo/whatever, there is no child to be harmed, so no problem.

I can convert them into pdf if you like. If you pm me with your email address, I will email pdf versions to you.

Hmmm... I thought it might have been the University's firewall, but now I am at home (on a different computer, also with Java) and it still doesn't work. Just a blank white page.

I get a blank screen too, and I have java installed.

No - you still can't have free-will, since the quantum 'decisions' which are made are by definition completely random. The probability that you perform an action can still be calculated exactly, so your 'decisions' can be predicted in a statistical sense. If you were able to influence this random choice in any way you would be in contradiction of physical law (since it would no longer be truely random). I disagree with Anjruu though - the random numbers are not picked in advance - they are chosen only when a quantum collapse occurs, so this physical outcome was not fixed at the start (although one could have predicted that this outcome would happen x% of the time).

While at a Austrian ski resort in the Alps, I was amused by Germans singing along to songs in an bar in a rather nice (though 'rustic') hotel. One song came on called 'Alice' (I think that is the title) and the bar would sing along to one line in particular (in English) which was 'Alice? Who the f*ck is Alice?'. There was no feeling among the singers that what they were singing was in anyway rude or offensive, and even the older ladies in their 60's were singing along! It made me feel slightly uncomfortable, but it made me see the illogicality of being offended by bad language.

Well, string theories need supersymmetry to be able to describe fermions. In fact the 'super' in 'superstrings' is the same 'super' as in 'supersymmetry'. So if supersymmetry were to be found, string theory would get an immense boost in credibility. On the other hand, if supersymmetry is not found at the LHC it doesn't mean that string theory is wrong. The LHC is only probing quite low energies, so it can only say that supersymmetry doesn't exist at low energies. But it could still exist at high energies where string theory is valid.

It seems to me that this is a rather bad definition since Darwin himself wouldn't have understood it. Genetics may provide a mechanical basis for evolution but it does not encompass the definition. A definition free from the mechanism should be given. Further, Lamarck's theory was also "evolution", just by a different (wrong) mechanism. In fact, we would do better debating "Natural Selection".

Do you think this is intended as serious, or is it a spoof? I seriously doubt anyone could be that stupid (unless they have mental problems).

Do you have a source? Because this was not what was reported at the time. I have tried looking at a few news sites but can't find any reference to it. I know it is the law, but that does not mean that they did - in fact, at the time, the media speculated that they might have been MI5 because they did not announce they were police.

I think there is an issue which has to be cleared up first. Did the police actually say they were police? I have heard it said on the news that they did not, but people here claim that they did. If they did, then I think they were justified in their actions. He was running from the police, disobeying their instructions, comitting an illegal act (the turnstyle) and potentially could have killed innocent civilians with a bomb if not stopped quickly. If they did not, how was he supposed to know they weren't gang members who would shoot him if he stopped? In fact, if they did not say they were police, they officer who shot him should be charged with murder.

No it isn't. By definition there can only be one universe, since what you are calling other universes would be in fact just parts of the same universe. People have to learn to describe their ideas in the proper language to try and prevent physics discussions degenerating into semantic squabbles (which this is by the way, and happens all too often at SFN).

The talks are now available at http://susy-2005.dur.ac.uk/susy-timetable.html

Really it would be clearer if we used the term 'limiting speed' or somesuch rather than 'speed of light'. The fact the light usually travels at this 'limiting speed' is rather besides the point.

As a matter of interest, since this is a scientific forum, let's present 2 'theories': 1. Evolution by natural selection: the accepted worldview of biologists and evolutionary scientists everywhere. 2. The belief that everything was created by a divine being 6,000 years ago, with the initial conditions set up so as to exactly mimic the state of the universe which would occur in theory 1 (6000 years ago). Can you present evidence between these two 'theories'? No, you can't, so it isn't a very scientific question, is it? Indeed, the second 'theory' is not really a theory at all (hence the quotation marks) since it doesn't explain how this was achieved. So please don't pretent this discussion is science. I personally don't find theory 2 reasonable, but I cannot say that it is wrong without making an aesthetic judgement. (Of course, creationists who say things like 'evolution doesn't happen' can be proven wrong, since we have seen it happening in organisms with very short generation times.)