Video: How String Theory scaled up

Mar 05, 2014 by Johnny Settle

In August 1984 two physicists arrived at a formula that transformed our understanding of string theory, an achievement now recognised by a major award. Professor Michael Green of the Department of Applied Mathematics and Theoretical Physics explains how string theory has taken unexpected directions.

In December 2013 Professor Michael Green of Cambridge University and Professor John Schwarz of California Institute of Technology were awarded the 2014 Fundamental Physics Prize, one of a series of annual 'Breakthrough Prizes' set up to raise the profile of the physical and biological sciences. Their shared $3 mn prize was given for "opening new perspectives on quantum gravity and the unification of forces".

Green and Schwarz are known for their pioneering work in , postulated as a way of explaining the fundamental constituents of the universe as tiny vibrating strings. Different types of elementary particles arise in this theory as different vibrational harmonics (or 'notes'). The scope of string theory has broadened over the past few years and is currently being applied to a far wider field than that for which it was first devised, which has taken those who research into it in unexpected directions.

Although the term 'string theory' was not coined till 1971, it had its genesis in a paper by the Italian physicist Gabriele Veneziano in 1968, published when Green was a research student in Cambridge. Green was rapidly impressed by its potential and began working seriously on it in the early 1970s. As he explains in the accompanying film, he stuck with string theory during a period when it was overshadowed by other developments in elementary particle physics.

As a result of a chance meeting at the CERN accelerator laboratory in Switzerland in the summer of 1979, Green (then a researcher at Queen Mary, London) began to work on string theory with Schwarz. Green says that the relative absence of interest in string theory during the 1970s and early 1980s was actually helpful: it allowed him and a small number of colleagues to focus on their research well away from the limelight.

"Initially we were not sure that the theory would be consistent, but as we understood it better we became more and more convinced that the theory had something valuable to say about the fundamental particles and their forces," he says.

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In August 1984 the two researchers, while working at the Aspen Center for Physics in Colorado, famously understood how string theory avoids certain inconsistencies (known as 'anomalies') that plague more conventional theories in which the are points rather than strings. This convinced other researchers of the potential of string theory as an elegant unified description of fundamental physics.

"Suddenly our world changed - and we were called on to give lectures and attend meetings and workshops," remembers Green.

String theory was back on track as a construct that offered a compelling explanation for the fundamental building blocks of the universe: many researchers shifted the focus of their work into this newly-promising field and, as a result of this upturn in interest, developments in string theory began to take new and unexpected directions.

Ideas formulated in the past few years, indicate that string theory has an overarching mathematical structure that may be useful for understanding a much wider variety of problems in theoretical physics that the theory was originally supposed to explain – this includes problems in condensed matter, superconductivity, plasma physics and the physics of fluids.

Green is a passionate believer in the exchange of ideas and he values immensely his interaction with the latest generation of researchers to be tackling some of the knottiest problems in particle physics and associated fields.

"The best ideas come from the young people entering the field and we need to make sure we continue to attract them into research. It is particularly evident that at present we fail to encourage sufficient numbers of young women to think about careers in physics," he says. "Scientific research is by its nature competitive and there are, of course, professional jealousies - but there's also a strong tradition of collaboration in and advances in the subject feel like a communal activity."

In 2009 Green was appointed Lucasian Professor of Mathematics at Cambridge. It comes with a legacy that Green describes as daunting: his immediate predecessor was Professor Stephen Hawking and in its 350-year history the chair has been held by a series of formidable names in the history of mathematical sciences.

The challenges of pushing forward the boundaries in a field that demands thinking in not three dimensions but as many as 11 are tremendous. The explanation of the basic building blocks of nature as different harmonics of a string is only a small part of string theory – and is the feature that is easiest to put across to the general public as it is relatively straightforward to visualise.

"Far harder to articulate in words are concepts to do with explaining how time and space might emerge from the theory," says Green. "Sometimes you hit a problem that you just can't get out of your head and carry round with you wherever you are. It's almost a cliché that it's often when you're relaxing that a solution will spontaneously present itself."

Like his colleagues Green is motivated by wonderment at the world and the excitement of being part of a close community grappling with fundamental questions. He is often asked to justify the cost of research that can seem so remote from everyday life, and that cannot be tested in any conventional sense. In response he gives the example of the way in which quantum mechanics has revolutionised the way in which many of us live.

In terms of developments that may come from advances in string theory, he says: "We can't predict what the eventual outcomes of our research will be. But, if we are successful, they will certainly be huge - and in the meantime, string theory provides a constant stream of unexpected surprises."

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User comments : 7

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vlaaing peerd
not rated yet Mar 05, 2014
String theory, my favourite sci-fi book.

Even if this theory doesn't turn out to be valid, it does emphasize we are missing something fundamental. Whatever the critique, anyone can understand there are signs (like the unification epoch of the universe, lack of gravity in QM) something more complete must be there. IMO well worth investigating and an interesting subject altogether.

It will be interesting to see what the LHC will bring on supersymmetry next year and what the string guys can make of it.

Bonia
Mar 05, 2014
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Bonia
Mar 05, 2014
This comment has been removed by a moderator.
vlaaing peerd
5 / 5 (4) Mar 06, 2014
we were not sure that the theory would be consistent
We can be sure, that the string theory is not consistent,...


What John Schwarz was referring to were the quantum anomalies which were solved in the Green-Schwarz mechanism. It is consistent and this is actually what drove many scientist to investigate string theory, because it showed such consistency.

I fail to see how you can so easily dismiss such a theory "because it has 10e500 solutions" and at the same time you're still blabbering about water bubbles on the surface of your completely disproven AWT, like me you understand dipsjit about strings and therefore your opinion doesn't have the least bit of authority to do such.

What I do understand is that in the early universe all the forces were once unified, there are problems with gravity in the SM, there is a gap between relativity and QM and we fail to describe common features of our universe so we call it singularities.
vlaaing peerd
5 / 5 (5) Mar 06, 2014
This makes it very valid to think there is a deeper theory that describes our reality more completely. String isn't just another theory that tries to do this, it actually addresses many of those problems in current physics.

Many theoretical scientists are aware that string theory could be completely off, but not for the 2D water bubble reasons mentioned here.

So as laymen one should know oneself and refrain from thinking to know better than the likes of Schwarz and even Einstein, Heisenberg, Susskind, Witten, Hawking (yes , your post history shows you think all of them are wrong) We should applaud these great men for giving us deeper understanding and insight into our reality -even if some is theoretical and perhaps wrong- .

But instead you replace the work of those great minds with ridiculous and utterly obsolete aether waves doing their 2D bubbling at the surface, don't you even think yourself this is starting to get ridiculous?
Rimino
Mar 06, 2014
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Rimino
Mar 06, 2014
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arom
not rated yet Mar 06, 2014
String theory was back on track as a construct that offered a compelling explanation for the fundamental building blocks of the universe: many researchers shifted the focus of their work into this newly-promising field and, as a result of this upturn in interest, developments in string theory began to take new and unexpected directions.

….
The challenges of pushing forward the boundaries in a field that demands thinking in not three dimensions but as many as 11 are tremendous. The explanation of the basic building blocks of nature as different harmonics of a string is only a small part of string theory – and is the feature that is easiest to put across to the general public as it is relatively straightforward to visualise.

Up to now, someone may ask for a more simple understandable realistic theory (which could explanation for the fundamental building blocks of the universe), maybe this idea could give some hint….
http://www.vacuum...=9〈=en

DarkHorse66
5 / 5 (1) Mar 10, 2014
Intuitivelly speaking, if we find some hyperdimensional shortcut (a worm hole) across 4D space-time, such a shortcut will manifest itself just with breaking of light speed limit - or it will not be a shortcut at all.

Re that shortcut and breaking of limit of 'c'.Not at all.You're implying that the actual distance in hyperdimensional space remains the same as the 'normal' distance& that the 'traveller' has to speed up to make their trip faster.That would mean that you are still within the same dimensions.The logical way to create that hypothetical wormhole(ie hyperdimensional shortcut)is do the equivalent of folding space&joining your starting with yourfinishing point. The easy way to illustrate this is:put two dots at opposite ends of a sheet of paper.Fold paper so that dots line up.Push a pin/straw thru the dots.Voila, you have just created a real shortcut between two distant points. No violation of limit of 'c' required.This would also mean that space is non-local.RegardsDH66
Bonia
Mar 10, 2014
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DarkHorse66
5 / 5 (1) Mar 10, 2014
You're implying that the actual distance in hyperdimensional space remains the same
Of course,the hyperdimensional space is Euclidean on its own.So how the hyperdimensional shortcut(a worm hole)would manifest itself according to you?

It would be TRANSdimensional.In other words, cutTHRU the dimensional fabric.You would still have Euclidian space INSIDEthe wormhole.This is not an impossible scenario.It is even possible that this is precisely what some of the additional dimensions in string theory actually are &that this model may work precisely because it accounts for all(or perhaps nearly all, since none of the models are perfect predictors for absolutely everything)of the existing dimensions beyond the 'obvious' ones
-Also, space IS elastic(or no space-time contractions/dilations)
-Every point in space is also a dimensional barrier
-Space/vacuum is not non-porous(else no particles appearing from(apparently)nowhere)
-Space/vac. is not continuous(isquantised)
RegardsDH66
Rimino
Mar 10, 2014
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DarkHorse66
5 / 5 (1) Mar 10, 2014
It would be TRANSdimensional
Whatever.. How the hyperdimensional shortcut (a worm hole) would manifest physically according to you? Would it glow in pink color or something similar?I presume, we're physicists here - not a phillosophers.

Since nobody has ever seen a real one,I can but speculate(hopefully in a reasonable manner)&deduce thru logical reasoning.Forget the representations from Star Trek, that's just to make it look pretty. In real life,one theoretical option is that they originate from a black hole (not my theory,somebody elses)So, what might one see,when looking at interdimensional 'stuff'..
Since it is an interdimensional shortcut..you would probably see some kind of cavity leading into some kind of tunnel.But that tunnel would not be our normal space,so you would probably see it no matter from which direction you looked.Perhaps as dark as normal space,perhaps lit up inside.Colour?Like Commander Data, I have insufficient information for that.
Reg.DH66
Rimino
Mar 10, 2014
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Rimino
Mar 10, 2014
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