Higgs' Boson? - We Have A Discovery

[Vile Consort]

Would you care to tell me what the square root of 2 is?

No. You are a complete tosser and not worth engaging with.

[Frances_iom]

It's the real irrational number which, when multiplied by itself, gives a result of 2. The fact that it cannot be expressed as a ratio of two integers makes it no less real.

merely less countable ?

[Gordon]

#94

Excellent!! That's how experiments go. These days some of them are very complex and one has to control conditions very well, so's not to fool oneself, and know what the results are actually saying, if anything. CERN, plant treatments, drugs etc etc. I'm not sure that physicists are any different to anyone else. The 5 sigma test is just a statistical confidence thing to give some assurance that the results are better than random.

One way to get to this level of confidence is to do an enormous number of trials. I think that is what CERN have been doing, huge numbers of proton collisions.

Brownian motion isn’t the kind of jiggling of particles that we have in mind in QM. However [and this is only my understanding so I don’t get VC wrath again] if we were to be able to peer deep into the structure of space well away from any “matter” we might “see” [not with real eyes of course but with a mind’s eye] lots of jostling. Entities coming out of nowhere and just as soon going again, not things that are always present and just moving around randomly. A kind of foaming, frothing of energy that disobeys the Conservation of Energy, but only for a tiny amount time, that only you are experiencing down there in the deep. Back up here in normal macroscopic space all goes on at a more sluggish pace and CofE isn’t affected. Nevertheless this jostling is not totally forbidden at macroscopic levels, just very unlikely.

Is anyone really comfortable with QM – who was it said if you aren’t shocked by it you don’t understand it? Trouble is the dratted theory seems to hold up. Apart from Heisenberg we also have that wretched cat of Schrodinger’s and that Superposition business that causes a lot of head scratching. One would have thought that a theory so weird would have rolled over and died long ago. So until some new genius comes along with a refinement or a compelling bit of experimental observation we’re stuck with it.

But... quantum computing:

We all know that 2 + 2 is 4, don't we, why would anyone doubt it? No one has to calculate what 2 + 2 is because they already know what it is, they have seen it before and it is memorised. Now ask a normal human being what 2.1953 + 2.0765 is and then they have to compute [ie “work it out”] because these are not everyday numbers whose sums are kept in the head.

How do they compute? Some rare folks can do it in their heads but most can't and need a pencil and paper AND an algorithm or series of ordered steps to arrive at a reliable result. The algorithm is independent of the numbers it processes. Everyone who has been to school knows all this.

So computing machines? What for? well to ease our burden of doing it and all the time it takes. We need a machine that can perform that algorithm instead of us and do it much much faster. The one feature of calculating machines that we really value is speed. Like calculating a Fourier Transform on the fly as happens of course in a DAB or DTT receiver. One of the great hopes [some would say promise] of quantum computing is to do the same things, and possibly more things too, at greater speed than conventional methods. How? we might ask. The theoreticians, of whom there are many, have published loads of intricate stuff about the mathematics but not a lot about how to build one. So it’s all a bit woolly at the action end.

I have to own up to being facetious. When I said that a Quantum Computer [QM] MIGHT say 2 and 2 wasn’t 4 etc I was speculating that if we adopt the probabilistic notions of QM that that is how a QC might respond. But that would not be good enough to replace our existing computing machinery, quantum computing does mean doing sums properly. Just as QM seems to suggest that particles are in a composite state until their probability functions collapse so some quantum structure might “know” all the answers until that uncertainty is collapsed? Pure speculation but not wholly inconsistent with some of the stuff you read in books.

But how? From what I have read one uses quantum entities like photon polarisations [Right hand/Left hand] or electron spins [Up/Down] to hold quantum bits. These sound familiar and binary. Then we invoke QS so that all possibilities of these quantum bits are sort of available at the same time, including the superposed ones, so that the photon [eg] state can be both R and L, and so the answers drop out when we ask for them like the collapse of a Schrodinger wave. Just like that. And quick too – [how do they know if they haven’t built one?] And 2 + 2 will be 4. Honest.

However no book or article I have read says exactly how to make a fully functional machine, not even close. QC has apparently been used in cryptography as a method of securely exchanging secret keys in a Diffie-Hellman system but it was slow and very cumbersome requiring magnetic fields and a stores of electrons spinning. Don’t sell your Intel shares just yet.

Anyway off to a birthday bash now.

[Gordon]

Ooh Dear!! trouble 'tmill!

#98

Well, Budapest, we do agree with you that the human race isn’t perfect. Given the gifts of science etc they do seem to latch on to the worst of it. Unfortunately that Pandora lady has lot to answer for but she’s long gone now. And let’s face it the God person isn’t that bothered either [no disrespect to believers]. He’s had several goes at setting us to rights but none of them seemed to work. But what do I know.

Some of them are perfectly good people [us for instance ] but there are some strange ones about as well. Lamentable, disappointing lot? Well, taken in the round, I suppose they are but for me that is mitigated somewhat by the decent people that I know and I find that comforting.

Anyway, to science. I do see what VC is saying about some of your statements. For example, you seem to confuse science with engineering. Don’t blame Newton because a space probe broke down. It’s a miracle that Voyagers have reached as far as they have without breaking. Yes, we have a lot to learn about building reliable machines that can get us safely further than the moon. Newton has told us enough about how to do it, it is not his fault that we haven’t the political, social and economic maturity to put the planet to rights AND do that exploration? We can do it all, we just can’t organise ourselves and we put all sorts of impediments in our own way. I would agree that until we have sorted this planet out we should not go polluting the rest of the solar system.

If I was God I’d have put an invisible cordon around the planet [perhaps he has] saying “Keep Out, Hazardous Species” in every galactic language there is….…..except English.

Anyway must go or all the fizz will have gone

[affenkopf]

But please, let's not try to blind people with science.

Agreed, let's keep science out of discussions of science. It only complicates matters.

[amateur51]

Agreed, let's keep science out of discussions of science. It only complicates matters.

[umslopogaas]

If anyone is interested in finding out more about the Higgs boson, there is an article about it in this week's New Scientist magazine (14 July).

[MrGongGong]

Vile Consort, there's never been a successful probe landing on Mars, a planet which has the most earth-like conditions in the solar system.

I won't at the moment address your other points, except to say that all science is based on a language called mathematics, which by its nature has to resolve (ie, sums have to add-up successfully). At the risk of going into 'pseudo-science' the thing about quantum physics is that the sums do not add-up, or at least they don't in the Newtonian universe.

But - and here's the 'but' - sums don't add-up in the Newtonian world, either.

What's the square root of 2?

Don't bother trying to work out the square root of 2, because it's unworkable. It doesn't resolve and as such is called an 'irrational number'.

Once again, at the risk of being accused of 'pseudo-science' or 'dumbing down', the basic fact is that all modern science is based on mathematics, and that mathematics is fundamentally flawed (it doesn't resolve successfully).

1 + 1 = 2

That's how our world is structured, but it's not how our present mathematics is structured.

Perhaps a good way at looking at quantum theory is trying to get back to 1 + 1 = 2

So go on shoot me, for trying to explain this in an understandable way.

Oh dear
I'm no mathematician (though my brother in law is at a rather well know university)
but it seems that you are confusing numbers with numbers of things
even my children learnt that this isn't the case at primary school
So i might suggest that instead of being confused you enrol for a GCSE maths course so that you get the basics

from what I remember you can't work out acceleration due to gravity if you keep insisting that the number 1 means 1 apple

[umslopogaas]

#108, Gordon, who was it who said "Anyone who is not shocked by quantum theory has not understood it."? It was Niels Bohr apparently, he's quoted on the back of Gribbin's book.

[Quarky]

Latest views on status of uncertainty principle:

http://www.livescience.com/18567-wacky-physics-heisenberg-uncertainty-principle.html

[Vile Consort]

Latest views on status of uncertainty principle:

http://www.livescience.com/18567-wac...principle.html

There's nothing new there. It's precisely what I was taught as an undergraduate in 1975 - including the bit about most people giving the wrong explanation. The explanation I was given went something like the following.

Imagine you have some apparatus that spits out electrons in the same quantum state. For a while, you measure the position of each electron (e.g. by observing where it hits a screen). The positions will be spread out somewhat, and you can calculate how far they spread from the average position (the value you want is the standard deviation). Now you stop measuring position and start measuring the momentum of each particle. Again you will see the readings spread out and you can calculate the standard deviation to quantify the spread.

Heisenberg's uncertainty principle tells you that, when you multiply the spread in position by the spread in momentum, the answer cannot be smaller than ħ/2, where ħ = h/2pi.

You will notice that the concept of disturbing the electron's momentum by measuring it's position (or vice versa) does not enter into this experiment: we measure the positions of one set of electrons, and the momenta of a completely different set.

Nor does the nature of the apparatus come into it. What the HUP tells us is that you can invent an apparatus that spits out electrons with very little variation in the position, but the variation in momentum will be large - and vice versa. You can't invent an apparatus where the spread in position and the spread in momentum are both arbitrarily small.

Another common misconception is that the HUP is something to do with the precision with which we can make measurements. We can measure the positions and momenta as precisely as we like, but the readings will still be spread out, and the amount of spread will be greater than the theoretical limit.

[Quarky]

Thanks for clarification - don't think I've heard that example before.

Although working in this area as recently as about 5 years ago, I find, whenever I pick the subject up after a long absence, I need to do a good deal of review before getting back into the "swim".

Ah well, quantum computing - here I come! http://www.youtube.com/watch?v=VtBRK...feature=relmfu

[Gordon]

#117:

.....Ah well, quantum computing - here I come! http://www.youtube.com/watch?v=VtBRK...feature=relmfu

Best of Luck!! Let us know how you get on.
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#114:

Thanks Omsie, that’s the fella! I knew it was one of those well known characters but couldn’t remember which one! Dreadful thing old age. I could have looked it up in one or other of the books in stock or even Googled but was too idle!!
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#115:

Thanks for that link OB, very useful in helping us get nearer to the heart of this uncertainty business.
=====================
#116:

Thanks VC for this, at last we have a more detailed description of an experiment to think about.

There's nothing new there. It's precisely what I was taught as an undergraduate in 1975 - including the bit about most people giving the wrong explanation. The explanation I was given went something like the following.

I could not see any Damascene flash either but what do I know. My undergraduate exposure to QM was quite a few years before yours, perhaps when people were more sure of themselves. If the professionals can’t agree on an explanation what chance students?

Imagine you have some apparatus that spits out electrons in the same quantum state. For a while, you measure the position of each electron (e.g. by observing where it hits a screen). The positions will be spread out somewhat, and you can calculate how far they spread from the average position (the value you want is the standard deviation). Now you stop measuring position and start measuring the momentum of each particle. Again you will see the readings spread out and you can calculate the standard deviation to quantify the spread.

Anyway, given some of the confusion in previous posts, let’s unpick this a bit and see if we get this right. Some questions if I may:

1 There is an implication that this machine will produce electrons at will with EXACTLY the same properties. Each one is indistinguishable from any other so it is just as if the same electron was being fired each time. Ignoring for the moment how we know that the machine does this except by measurement, is that right?

2 If so, in the absence of any disturbing influence, each electron ought [ie according to classical dynamics] to end up in exactly the same place on the detector screen? But in the experiment they appear not to, so we have to ask why? This is the essence of quantum uncertainty.

3 However, what you said was the same “quantum state” which implies that they may not be EXACTLY the same, there is some uncertainty associated with that state. Below you say “Nor does the nature of the apparatus come into it” so, although it has to intercept the electron and be able to express its location somehow, the detector has no role in the spread in the position of the landing place of successive electrons? Is that right? This is the bit that is hard to appreciate. It’s hard not to expect some quantum process in the detector.

4 The implication is that each electron landing location can be measured to arbitrary precision [see below] that is, there is NO limit to how precisely any one electron’s location, ie a point in space, can be known. The spread is the result from an ensemble of electrons that expresses their uncertainty not that of the detector. So taken together, this says that measuring “quantum” things is not hard because the measuring is limited in itself, it is because of the way that the quantum things are assembled. Is that right?

5 If so, one has to ask how because the electron has a finite physical classical particulate size and a finite wavelength [or wave packet pdf]. So what does an arbitrarily precise location mean? Which bit of the electron does the detector detect and place at that fine point in space? It seems like being asked to put an elephant on the equator – which bit of the elephant goes on the line? Or is that another stupid question? What am I missing?

Heisenberg's uncertainty principle tells you that, when you multiply the spread in position by the spread in momentum, the answer cannot be smaller than ħ/2, where ħ = h/2pi.

Yes. Is this analogy right?

If our machine is like a darts player it can produce electrons that hit the screen in a tight group like some expert player but it can’t get the momentum range of the darts as they hit the board below a minimum. Similarly if that player could hit the board with darts having very tightly grouped momenta then the landing points on the board cannot be grouped more tightly than a given minimum. Simples! cue Merecat.

[Abraham Lincoln comes to mind here! “You can fool some of the people all of the time, and all of the people some of the time, but you can not fool all of the people all of the time.”…..quantum politics?]

You will notice that the concept of disturbing the electron's momentum by measuring it's position (or vice versa) does not enter into this experiment: we measure the positions of one set of electrons, and the momenta of a completely different set.

Y-e-e-e-e s. Let’s look at this a bit further because this is important.

What happens at that screen? In this experiment the information is gathered such that we do not try to measure two properties of the same electron at the same time. Just before any one electron arrives at a detector [the screen] it has a set of properties, we don’t know the value of any of them. What’s more we don’t actually tie it down to being anywhere in particular, we just have a probability function around it that tells where it might be. Our location detector is set up to measure one and only one property and if there is an inherent uncertainty in the electron states the indicated locations will be affected?

Nor does the nature of the apparatus come into it. What the HUP tells us is that you can invent an apparatus that spits out electrons with very little variation in the position, but the variation in momentum will be large - and vice versa. You can't invent an apparatus where the spread in position and the spread in momentum are both arbitrarily small.

Yes, I think. See query above regarding the detector.

Another common misconception is that the HUP is something to do with the precision with which we can make measurements. We can measure the positions and momenta as precisely as we like, but the readings will still be spread out, and the amount of spread will be greater than the theoretical limit.

See query above.

I think I’ll have a little lie down now, dark room, cold compress on head.

[Vile Consort]

I could not see any Damascene flash either but what do I know. My undergraduate exposure to QM was quite a few years before yours, perhaps when people were more sure of themselves. If the professionals can’t agree on an explanation what chance students?

My lecturers were pretty sure of themselves, I can tell you!

Anyway, given some of the confusion in previous posts, let’s unpick this a bit and see if we get this right. Some questions if I may:

1 There is an implication that this machine will produce electrons at will with EXACTLY the same properties. Each one is indistinguishable from any other so it is just as if the same electron was being fired each time. Ignoring for the moment how we know that the machine does this except by measurement, is that right?

Good point. I think the answer is that the apparatus has conducted some meaurements and therefore got all the electrons into the same state. The state then evolves according to the Schroedinger equation whereupon everything becomes fuzzy again, with superpositions of states.

2 If so, in the absence of any disturbing influence, each electron ought [ie according to classical dynamics] to end up in exactly the same place on the detector screen? But in the experiment they appear not to, so we have to ask why? This is the essence of quantum uncertainty.

Quote so.

3 However, what you said was the same “quantum state” which implies that they may not be EXACTLY the same, there is some uncertainty associated with that state. Below you say “Nor does the nature of the apparatus come into it” so, although it has to intercept the electron and be able to express its location somehow, the detector has no role in the spread in the position of the landing place of successive electrons? Is that right? This is the bit that is hard to appreciate. It’s hard not to expect some quantum process in the detector.

I meant the nature of the apparatus producing the electrons. What I was trying to get at was that it isn't some shortcoming of the apparatus producing the electrons that results in the uncertainty.

4 The implication is that each electron landing location can be measured to arbitrary precision [see below] that is, there is NO limit to how precisely any one electron’s location, ie a point in space, can be known. The spread is the result from an ensemble of electrons that expresses their uncertainty not that of the detector. So taken together, this says that measuring “quantum” things is not hard because the measuring is limited in itself, it is because of the way that the quantum things are assembled. Is that right?

5 If so, one has to ask how because the electron has a finite physical classical particulate size and a finite wavelength [or wave packet pdf]. So what does an arbitrarily precise location mean? Which bit of the electron does the detector detect and place at that fine point in space? It seems like being asked to put an elephant on the equator – which bit of the elephant goes on the line? Or is that another stupid question? What am I missing?

Yes. Is this analogy right?

The size of an electron is of the order of 10^-15 metres, so it is far, far smaller than the uncertainty effects. You can't define lines to that accuracy because they would jump around all over the place owing to the Heisenberg Uncertainty Principle. It's more like firing elephants at the sun than firing them at the equator.

In any case, the size of the electron can't be seen as the same sort of thing as the size of a billiard ball. It's the result of looking at the probability of electrons interacting with photons and then saying that, if the electron were like a billiard ball, this is the size it would need to be to bump into photons with that probability.

Again, if you did try to observe something of that size, quantum uncertainty would completely obliterate your measurements.

If our machine is like a darts player it can produce electrons that hit the screen in a tight group like some expert player but it can’t get the momentum range of the darts as they hit the board below a minimum. Similarly if that player could hit the board with darts having very tightly grouped momenta then the landing points on the board cannot be grouped more tightly than a given minimum. Simples! cue Merecat.

A simple illustration is a screen with a hold in it, with an electron gun firing at it from one side. Now place a screen on the other side to see where the electrons land. If the hole is large, the electrons go more or less straight through it, forming a parallel beam the same shape as the hole. This is because there's plenty of uncertainty as to their position as they pass through the hole, so their momentum doesn't spread out much. Now make the hole very small, and the electrons come out radiating in all directions. This is because we've contained their position (in the plane of the screen) very narrowly, so their momenta (in the plane of the screen) become very uncertain around the average value of zero.

[Abraham Lincoln comes to mind here! “You can fool some of the people all of the time, and all of the people some of the time, but you can not fool all of the people all of the time.”…..quantum politics?]



Y-e-e-e-e s. Let’s look at this a bit further because this is important.

What happens at that screen? In this experiment the information is gathered such that we do not try to measure two properties of the same electron at the same time. Just before any one electron arrives at a detector [the screen] it has a set of properties, we don’t know the value of any of them. What’s more we don’t actually tie it down to being anywhere in particular, we just have a probability function around it that tells where it might be. Our location detector is set up to measure one and only one property and if there is an inherent uncertainty in the electron states the indicated locations will be affected?

Most physicists would disagree with your statement "just before any one electron arrives at a detector [the screen] it has a set of properties, we don’t know the value of any of them". You are articulating the "hidden variable" theory that Einstein clung on to. Bohr's position was that it didn't make sense to speak of the position of an electron until you actually measured it, that when you weren't measuring it, any properties it might have were, by definition, unobservable, and therefore no statement made about those unobserved properties could be either proved or falsified; such statements were on a par with statements about angels.

In the 1960's, John Stewart Bell designed an experiment that would be able to distinguish whether there were really hidden variables or not. The experiment (or a variant of it) was first performed by Alain Aspect in the early 1980's and it has been performed many times since with increasing confidence in the results. The experiments show that hidden variables are inconsistent with observed behaviour.

The details are too complicated for me to explain here. No, it's worse than that: they are so complicated that I think I understand it every time I read it, but as soon as I finish reading, it slips away from me. Hmm ... seem to remember some of my lecture notes were like that!



I do realise re-reading what I've written that I haven't explained it very well and that, indeed, there are many aspects of it that I don't fully understand.

[Budapest]

No one here has yet explained how a fly can 'fly'. I believe someone said earlier that it is 'instinct', which is not very scientific, but might well have to do.

(for those who haven't been following this thread, the point about a fly is that its aerial acrobatics take an incredible amount of computation, yet a fly has a very small brain)

To try and put it into some kind of context, modern computers have about 4 Gigabytes of RAM (Random Access Memory). A fly must have about 200 Gigs of RAM in order to do what it does - buzzing around and driving everyone mad.

When you put the memory against the speed of computation, folks like me will tell you that it can only work at a quantum level. There's no other known way that it can work.