End of Physics

Pakistan vich Gill vi hunde hai!

Gill to pehle Singh te hamesha sunya dekhya si par Muhammad Akram pehli vaari dekhya.

Satnam Sri waheguru! Ki hoyega is duniya da?

Anyway, Mr. Gill Article is Good. my favurite teacher used to be a Dr. Gill but then he is a Singh Gill.

Dear Mr Harmonica and Anaryan ji:

Let me first express my appreciation for the comments made by Mr. Harmonica. His comments have added to the value of the paper and I thank him for that. Now,

regarding proton (in)stability, some GUTs had predicted ‘proton decay’. The proton decay life-time is however very long, longer than the age of the universe, it is of the order of 10

Dear Gill Sahib,

Thanks for posting the informative piece which does respond to some of my questions. It does seem clear from whatever I have read on the subject that the ``laws of physics`` as we perceive them at our scale are turned on their head by laws at the subatomic scale where all sorts of strange things happen - particles that can be in two places at the same time (which I believe has led people to conjecture of multiple universes that are some kind of a mirror image of one another); particles that change their behavior when they are observed (as I mentioned earlier). And yet, based on such theories and hypotheses, mankind is able to come up with very real and tangible results (e.g. the nuclear bomb, electric power, wireless communication).

I think the true leaders of mankind are scientists. Politicians and demagogues and military generals will come and go and not leave a trace behind. The work of the scientist actually moves man one step closer to his God-given mission: to understand His creation as best as he can. And in doing so, will make life much more comfortable and interesting for future generations as well.

Akramji,

``...ninety times the mass of the proton (the heaviest known stable particle) ...``

I guess you mean short-term stability here. Please correct me - I thought the proton was the ONLY unconditionally stable particle. Sometime back I read physicists were trying to test the proton`s ultimate stability with some unique experiments. If you are keeping track of that could you tell us the results of that experiment or is it still going on ?

The results were apparently important in that they would tell us whether all matter would ultimately end up as radiation or not.

Thanks and regards,

Dear Mr Tahmed (and other readers):

Thank you for your interest in my essay “End of Physics”. You have raised several questions in your ‘feed back’. I am not sure if I will be able to answer all of them to your satisfaction but let me try. I am going to take help from the published works of several physicists in doing so. I cannot do better than starting with a rather detailed extract from Paul Davies. There are four fundamental forces of nature as I had mentioned in the essay. According to Davies (1):

Why should nature deploy four different forces? Wouldn’t it be simpler, more efficient, and more elegant to have three, or maybe two or even one force, but with four distinct aspects? Or so it seemed to the physicists concerned, and so they looked for similarities between the forces to see if any mathematical amalgamation were possible. In the 1960s promising candidates were the electromagnetic force and the weak nuclear force. The electromagnetic force was known to operate through the exchange of particles called ‘photons’. These photons flit back and forth, between electrically charged particles such as electrons, and produce forces on them… You can think of these photons as rather like messengers, conveying the news about the force between particles of matter, which must then respond to it.

Now, theorists believed that something similar was going on inside nuclei when the weak nuclear force acts. A hypothetical particle, cryptically known as W, was invented to play a messenger role analogous to that of the photon. But whereas photons were familiar in the lab, nobody had ever seen a W, so the main guide in this theory was mathematics. The theory was recast in a way that brought out its essential similarity to electromagnetism most suggestively. The idea was that, if you have two mathematical schemes more or less the same, you can join them together and make do with a single, amalgamated scheme. Part of this rejigging meant introducing an additional messenger particle, known as Z, which resembles the photon even more closely than does W. The trouble was, even in this new improved mathematical framework the two schemes – electromagnetism and the weak- force theories – still differed in one rather basic way. Although Z and the photon share many properties, their masses have to be at opposite ends of the spectrum. This is because the mass of the messenger particle is related in a simple way to the range of the force: the more massive the messenger particle, the shorter the range of the corresponding force. Now, electromagnetism is a force of unlimited range, requiring a messenger particle of zero mass, whereas the weak force is confined to sub -nuclear distances and requires its messenger particles to be so massive they would outweigh most atoms.

Let me say a few words about the masslessness of the photon. The mass of a particle is related to its inertia. The smaller the mass, the smaller the inertia, so the faster it will accelerate when pushed. If a body has a very low mass, a given impulse will impart a very great speed. If you imagine particles with less and less mass, then their speeds will be greater and greater. You might think that a particle with zero mass would move at an infinite speed, but that is not so. The theory of relativity forbids travel faster than light, so zero-mass particles travel at the speed of light. Photon, being ‘particles of light’, are the obvious example. By contrast, W and Z particles were predicted to have masses of about eighty and ninety times the mass of the proton (the heaviest known stable particle), respectively.

The problem the theorists faced in the 1960s was how to combine two elegant mathematical schemes describing the electromagnetic and weak forces if they differ so markedly in one important detail. The break through came in 1967. Building on the mathematical framework constructed some time earlier by Sheldon Glashow, two theoretical physicists, Abdus Salam and Steven Weinberg, independently spotted a way forward. The essential idea was this. Suppose the great mass of W and Z is not a primary quality, but something acquired as a result of interaction with something else; that is, suppose these particles are not so to speak, born massive, they are just carrying someone else’s load? The distinction is a subtle one, but crucial. It means that the mass is attributed to the underlying laws of physics, but to the particular state that the W and Z are usually found in.

An analogy might make the point clear. Stand a pencil on its tip and hold it vertical. Now let it go. The pencil will topple over and line up in some direction. Say it points northeast. The pencil reached that state as a result of the action of the Earth’s gravity. But its ‘northeasterliness’ is not an intrinsic quality of gravity. The Earth’s gravity certainly has an intrinsic ‘up-down-ness’, but not a north-south-ness or an east-west-ness or anything in between. Gravity makes no distinction between different horizontal directions. So the northeastness of the pencil is merely an incidental property of the system pencil-plus- gravity that reflects the particular state that the pencil happens to be in.

In the case of W and Z, the role of gravity is played by a hypothetical new field, called a Higgs field after Peter Higgs of the University of Edinburgh. The Higgs field interacts with W and Z and causes them to ‘topple over’ in a symbolic sense. Rather than picking up ‘northeast-ness’, they pick up mass – and lots of it. The way is now open to unification with the electromagnetic force, because, underneath, W and Z are ‘really’ massless, like the photon. The two mathematical schemes can then be amalgamated, yielding a unified description of a single ‘electroweak force’.

The rest, as they say, is history. In the early 1980s accelerators at the Centre for European Nuclear Research (CERN), near Geneva, finally produced W particles, and then Z. The theory was brilliantly confirmed.

Another part of the story is described by Tipler. According to him (2), “Yang and Mills invented local gauge theory in 1954, Glashow applied the ideas to get an electroweak theory in 1961, but as particle masses were put in hand, the theory was manifestly inconsistent. Weinberg and Salam added the Higgs mass generation mechanism to Glashow’s theory in 1967 and 1968 respectively and t’Hooft proved that the Glashow-Weinberg-Salam theory was mathematically consistent in 1971”.

Dr Peter Higgs was born on May 29,1929. He taught at the University of Edinburgh. As part of the UK Institute of Physics conference Particle Physics 2000, in Edinburgh, a special conference was held to celebrate his 70th birthday anniversary. Speaking at this conference, Higgs (3) stated, “Apparently the famous Higgs particle was the result of three weeks’ work in the mid 1960s. The first two weeks were spent writing a paper and having it rejected by the referee on the grounds that quantum field theory was obscure and of little interest. The referee suggested that the paper might be improved by the addition of some practical consequences of the theory. The third week was spent providing these examples, which included the Higgs particle”. Lederman (4) has dubbed the Higgs particle as the God Particle and has written a whole book with that title. “Why God particle?”, he asks. “Two reasons”, he suggests. “One, the publisher wouldn’t let us call the Goddamn Particle, though that might be a more appropriate title, given its villainous nature and the expense it is causing. And two, there is a connection, of sorts, to another book, a much older one”. Dr Higgs has received several honours and awards for his work.

It was possible to unify the electromagnetic and weak forces into one electroweak force using the Higgs particle as observed above. It will give us a GUT also but can it unify gravity with GUT? Here the opinions diverge. Some believe it can, others are not so sure.

I hope the above description might help you to at least have a slightly better understanding. With kind regards,



Mohammad Gill

REFERENCES

1.Davies, P., “The Mind of God”, Simons and Schuster, New York, 1992, pp. 207-208.

2. Tipler, F.J., “The physics of Immortality”, Anchor Books, A Division of Random House, Inc., New York, 1995, p.146.

3.”Higgs is Honoured in Edinburgh”, wysiwyg://204/http:www.cerncourier.com/main/article/40/6/5.

4. Lederman, L, with Dick Teresi, “The God Particle”, Houghton Mifflin Company, Boston, 1993, p. 22.

free

harmonic #8 So the smallest thing possible is not a string but a membrane. I thought I was already confused - what does that make a half-string? half the size of the smallest thing possible? but that is a contradiction in terms. And now here comes the membrane. what does that make a piece of the membrane? I am still waiting for the writer to come back with a response to my earlier questions, and here we have some more.

The author talks about the increasing coastline of ignorance with an expanding island of knowledge: Seems to me what we have on this board is an increasing coastline of ignorance with a contracting island of knowledge. Unless the learned author or the other learned ones like you are prepared to explain to non-knowledgeable ones like self.

Good article. A little out dated though. There has

been a revolution in string theory since 1993-94.

And infact, it has been realised that the theory is much more complicated and interesting than previously thought. The problem with string theory is that it is not clear what the theory is because most things are very hard to calculate and the theory is a hard to formulate based on a fundamental symmetry principle. However, over the last 8 years or so, it has been realised that certain quantities can be calculated exactly and they point to an amazing unification within the context of string theories. Before 1994, it was thought that there are 5 different possibly consitent string theories one could write down. However, recently, it has been realised that there five different string theories are actually different phases of the same theory, and infact there is another theory, called M-theory which emcompasses all the different string theories. M-theory lives in 11 dimensions and not 10. It is NOT a theory of strings. At long distances, it looks like a theory called 11 dimensional supergravity, which is basically a very souped up version of Einstein`s General relativity in 11 dimensions. At small distances, its not clear what the theory is yet although some facts are known. For example it is known that the theory has membranes, not strings. If anything is a theory of everything, M-theory is considered to be it. However, because we know so little about this theory, we are very very far from the end of physics.

A few other points:

1)There have been some recent theoretical advances

which makes it possible that actually the scale at which string effects become important is not 10

Interesting article.
Wonder where CHOWK`s strings are these days?

Ras

wow...thanks for the detailed article.

was pretty informative and interesting even for someone with little physics background:)

Yes, Physics has ended!

Otherwise DR Pervez RobinHood wouldnt have harped and hopped around giving lectures on Foreign Policy and Politics!!

*sniggers *

Akram Sahib: Thanks for a well written and carefully documented article. A couple of questions from an ignoramus: First: How does the superstring theory relate to the search for the elusive Higgs boson? Also, who was Higgs and why is the particle called a ``boson`` and not a ``quark`` like other self-respecting particles? I hear a the Higgs boson is expected to be a monstrous particle, the size of a neutron. So why is it so elusive?

On the tachyon, I think the death knell you sound may be premature, according to at least one scientist writing in the Washington Post today who thinks it may exist (the particle goes faster than light, thus breaking Einstein`s theory incidentally). For your convenience, I have cut a paste extracts from it at the end of this post.

Question on Heisenberg: Is he not the man who was also trying to build the nuclear bomb for Hitler? And also the man who explained how elementary particles start misbehaving when they are observed - the Heisenberg Uncertainty Principle I think it is called. How does that fit in with TOE?

Any responses on any of the questins above would be appreciated. Thanks for a good article.

The extract from the WP follows.

``The main reason most physicists doubt the existence of tachyons is ... nearly all experiments searching for these faster-than-light particles have turned up negative...Tachyons have the bizarre property of having a mass (whose)square is a negative number. The idea of an imaginary mass seems completely crazy if you think in terms of measuring an object`s mass or weight on a scale, but that`s not how particle masses are found. What`s done is to infer the mass based on experiments where you measure the speeds of other particles reacting with that particle. It`s like measuring the mass of your car by observing the way it affects other cars during crashes...]

Akramji,

Thanks for your article. Superstrings certainly are in the forefront of physics today. Couple of years back I picked up a nice book on the topic from the library and managed to wade through it (`m not a physicist ).

If I`m not very mistaken, the basic idea behind the theory is that sub-atomic particles can be `modelled` as being composed of tiny vibrating strings. It doesn`t say that these particles are indeed composed as such - just that their behavior can be explained thusly. An estimate of the size of these strings is 10 power -33 meter (or cm ?). This is far far far beyond anything we can examine experimentally - which brings me to our concluding statement: ``At the same time, the story underlines the importance of experimental verification of theoretical predictions.``

As regards the ``end of science``, that is surely far fetched IMHO. The history of science is littered with such `final` predictions. Some great man of science in the nineteenth century ( don`t recall who), said that everything of worth had already been discovered by 1900 !

Looking at it simply - every object ( a superstring for eg. ) that has a quality ( eg. vibration) can be asked this question: what causes it to have that quality. Pursuit of knowledge is endless.

Reminds me also of Jose Capablanca, the world chess champion, who after laying low all opponents claimed that chess needed to be redesigned (bigger board, more pieces), since all possible variations had been exhausted. He was beaten by Alekhine in the next match.

regards

Mr.Akram Gill

Thank you for a lucid article on an enigmatic & complex subject.

Such is the stuff that ones` learning of the english language is put to proper use.

The island & coast of ignorance concept:

``Zakhm key bharnay talak naakhun naa burrhh ayaiN gay kia.`` ?

and then that saying by Hazrat Ali we are all familiar with.

wassalaam.