Tag: Quantum mechanics

Talking physics with your dog!

Not as silly as one might think!

Back on the 25th April I ran a Post called Dogs and the Mathematics of Calculus that had been prompted by a lovely email from Richard Hake who is Emeritus Professor of Physics at Indiana University.  (Now here’s a question for yours truly; what does it mean for a Professor to be an Emeritus Professor? Answers as comments please.)

It was very well received.  Then just a few days ago Professor Hake, who admits to being a dedicated lurker of this blogsite, sent me another email with a number of fascinating links.  So here goes with one of those links.

Talking to Your Dog About Physics

A conversation with Chad Orzel

So, why do you talk to your dog about physics?

Lots of reasons, but the main one is that I’m a physics professor. Talking about physics is what I do. Sooner or later I talk to everybody about physics.

I bet that’s a big hit at parties.

You might be surprised. I mean, sure, I get a lot of people making faces and saying how much they hated physics when they took it in college. But some of those same people turn right around and start asking interested questions about the subject.

OK, but why the dog?

Talking to the dog about physics is worthwhile because it can help me see how to explain physics to my human students. Humans all come at the subject with the same set of preconceptions about how the world works, and what “should” happen, and it can be very hard to shake those off. That’s a big barrier to understanding something like quantum physics.

Dogs look at the world in a very different way. To a dog, the world is a neverending source of wonder and amazement. You can walk your dog past the same rock every morning, and every morning, she’ll sniff that rock like she’s never sniffed it before. Dogs are surprised by things we take for granted, and they take in stride things that would leave us completely baffled.

Can you give an example?

Well, take the dog’s bowl, for example. Every now and then, we put scraps from dinner in the bowl when she’s not looking, and she’s become convinced that her bowl is magic– that tasty food just appears in it out of nowhere. She’ll wander over a couple of times a day, and look just to see if anything good has turned up, even when we haven’t been anywhere near the bowl in hours.

This puts her in a better position to understand quantum electrodynamics than many humans.

It does?

Sure. One of the most surprising features of QED, in Feynman’s formulation, is the idea of “virtual particles.” You have an electron that’s moving along, minding its own business, and every now and then, particle-antiparticle pairs just pop into existence for a very short time. They don’t stick around very long, but they have a real and measurable influence on the way electrons interact with each other, and with other particles.

You’re making this up, right?

No, not at all. One set of these interactions is described by a number called the “g-factor” of the electron, and this has been measured to something like fifteen decimal places, and the experimental measurement agrees perfectly with the theoretical prediction. If there weren’t electrons and positrons popping out of nowhere, there’s no way you could get that sort of agreement.

So, what’s this have to do with the dog?

Well, like I said, the dog is perfectly comfortable with the idea of stuff popping into existence out of nowhere. If a great big steak were to suddenly appear on your dining room table, you’d probably be a little perturbed. The dog, on the other hand, would feel it was nothing more than her due.

So she’s perfectly ok with the idea of virtual particles, unlike most humans, who tend to say things like “You’re making this up, right?” She was already convinced that there were bunnies made of cheese popping in and out of the backyard, and just regards QED as a solid theoretical justification for her beliefs.

And this helps humans, how, exactly?

Physics has a reputation as a difficult and unapproachable subject, especially in fields like quantum mechanics, where the predictions of the theory confound our human preconceptions. If you can put aside a few of your usual notions of how the world works, and think about how things look to a dog, some aspects of physics that seem absolutely impossible to accept become a lot more approachable.

Why does this matter, though? Isn’t this all stuff that you need a billion-dollar particle accelerator to see?

Actually, no. It’s a common misconception, but most of the really cool aspects of quantum mechanics that we talk about in the book are experiments that are done on a table-top scale. One of them, the “quantum eraser,” you can even do yourself with a laser pointer and a couple of pairs of polarized sunglasses.

OK, but what is it good for, in a practical sense?

Lots of things. It’s not an exaggeration to say that modern life as we know it would be impossible without an understanding of quantum phyiscs. You need to understand quantum ideas to build the lasers we use in modern telecommunications, and the transistors that are the basis of all modern electronics. The computer I’m typing this on wouldn’t exist without quantum physics.

And there are a whole host of future technologies that are based on quantum ideas. There are exotic applications like quantum computers that can do calculations that would be impossible with any normal computer, and quantum cryptography systems that allow us to make unbreakable codes. But even relatively mundane “green” technologies like more efficient light bulbs, batteries, and solar panels rely on quantum ideas to work.

Quantum physics is everywhere, and drives a huge amount of modern science and technology.

So that’s why people should teach quantum physics to their dogs?

Exactly. Also, it’s just about the coolest thing ever.

How to Teach Physics to Your Dog is published by Scribner can be ordered from Amazon.comIndieBound,Barnes and Noble, and Powell’s.

How to Teach Relativity to Your Dog is published by Basic Books and can be ordered from AmazonBarnes & NoblePowell’s.

 

Talking or sleeping about physics?

OK, two thoughts to close this off.  The first is to remind you of an early sentence that Chad Orzel wrote, “Talking to the dog about physics is worthwhile because it can help me see how to explain physics to my human students.” and to add that in my next life, I wouldn’t mind coming back as one of Chads dogs!

The second thought is that Chad’s talks with his dogs are pretty relaxed affairs, as the picture above bears out!

Thank you, Professor Hake!

 

The mystery of telepathy

Just a bit more science about that sixth sense.

Yesterday, I wrote about how science was coming up with some pretty strong evidence that humans do have the ability to communicate in a way that might be called ‘telepathic’.

If (and that’s a big ‘if’) I have any understanding of the science, I believe it has much to do with quantum physics.  So I thought it fun to take a small diversion in today’s Post and give you some material on this very strange world of the very, very small.

From A Lazyman’s Guide to Quantum Physics,

What is Quantum Physics?

That’s an easy one: it’s the science of things so small that the quantum nature of reality has an effect. Quantum means ‘discrete amount’ or ‘portion’. Max Planck discovered in 1900 that you couldn’t get smaller than a certain minimum amount of anything. This minimum amount is now called the Planck unit.

Why is it weird?

Niels Bohr, the father of the orthodox ‘Copenhagen Interpretation’ of quantum physics once said, “Anyone who is not shocked by quantum theory has not understood it“.

To understand the weirdness completely, you just need to know about three experiments: Light Bulb, Two Slits, Schroedinger’s Cat.

Two Slits

The simplest experiment to demonstrate quantum weirdness involves shining a light through two parallel slits and looking at the screen. It can be shown that a single photon (particle of light) can interfere with itself, as if it travelled through both slits at once.

Light Bulb

Imagine a light bulb filament gives out a photon, seemingly in a random direction. Erwin Schroedinger came up with a nine-letter-long equation that correctly predicts the chances of finding that photon at any given point. He envisaged a kind of wave, like a ripple from a pebble dropped into a pond, spreading out from the filament. Once you look at the photon, this ‘wavefunction’ collapses into the single point at which the photon really is.

Schroedinger’s Cat

In this experiment, we take your pet cat and put it in a box with a bottle of cyanide. We rig it up so that a detector looks at an isolated electron and determines whether it is ‘spin up’ or ‘spin down’ (it can have either characteristic, seemingly at random). If it is ‘spin up’, then the bottle is opened and the cat gets it. Ten minutes later we open the box and see if the cat is alive or dead. The question is: what state is the cat in between the detector being activated and you opening the box. Nobody has actually done this experiment (to my knowledge) but it does show up a paradox that arises in certain interpretations.

To conclude I will offer this quotation reputed to be from the great master himself, Albert Einstein,

The more success the quantum theory has, the sillier it looks.

Beautiful minds, today Stephen Hawking

The second of two fascinating films about two very beautiful minds, Hugh Everett III and Stephen Hawking.

I am slightly hesitant in pursuing this, after my article about Hugh Everett on the 19th.  Said slightly tongue-in-cheek following a fascinating, as always, exchange of comments with Patrice Ayme.  Here’s a taste of Ayme’s writings, and here’s the exchange,

Patrice first wrote,

The question is: what happened? The multiverse answer is that, whatever it is, it happened in one universe, and it did not happen, in another universe. And if it is not a matter of discrete choice, as in a 2 slit experiment, an uncountable number of universes will be created. In other words, if one wants a proof of the insanity of some of today’s physicists, the multiverse is all we need. According to this lamentable spasm of the mind, during every single, smallest amount of time imaginable, an uncountable infinity of universes appear.

OK, the inflationary universe has the same problem, and is about as insane. But being surrounded by mad men does not excuse one’s own insanity. So we shall laugh.

To which I replied,

Dear Patrice, the challenge presented at this end, in terms of how to evaluate your comment, is that your anonymous profile (that is truly respected, by the way) makes it impossible to determine your academic and social backgrounds. Therefore are you replying from the position of a great thinker, or of a great thinker with significant scientific and philosophical accreditations? Your writings are powerful and impressive but nonetheless to assume (as I read into your approach) that the world of quantum physics is a ‘done deal’ is not something I can share. I anticipate that you will feel similarly ready to laugh on Thursday when I publish some words on Stephen Hawking. ;-)

Eliciting a further very thoughtful reply from PA,

Thoughts have to learn to stand on their own. The authority fallacy (if you forgive this neo sentence) is no ersatz for truth. Some (previously) immensely respected physics Nobel prizes were member of the Nazi party before Hitler. That did not make their physics any less insane.

Most top thinkers of the scientific revolution in the 17C were not respected tenured professors at the university (although Galileo and Newton were, not so for Kepler, Bruno,Descartes, Fermat, Pascal, Leibnitz…). We have no historical distantiation to judge what’s going on now.

I respect some of the work of Hawking. And certainly respect him tremendously as a person (although he dumped his wife for his nurse).

I appreciate the fact you tease me with Quantum Mechanics as a “done deal”. I actually believe that QM is the most precise theory we have, but it’s most certainly false or crazy as Newton basically said about his own theory of gravitation, and pretty much for the same reasons… This shows that I have to express myself more clearly…

In any case QM got no traction with the Quantum computer, so far. To say the least, many questions have been found to not be answered…

As far as accreditations are concerned, I will refer to the PhDs of Qaddafi’s children, and the movie “Ghostwriter”. Speaking of Harvard, what about Huntington’s “Clash of Civilizations”, of an incredibly low scholarly level, and the numerous professors there on Qaddafi’s payroll? Does that mean they were accreditated by Qaddafi?

I am quite familiar with academia, and I think too much credit is given, quite often.

I am going to put a more extended version of my various remarks on my site, insisting on the fact QM, however impressive, is no deal. The multiverse was a desperate attempt to make it a deal, precisely, as it was made to eschew the problem of the non existence of a detailled mechanism of wave packet collapse. [Ironically I was once punished on a “philosophy” site for saying that QM was a live subject of research; I never went back to that site, which has academic pretentions: they had told me they checked with physics professors…]

Best wishes to you too, and I look forward chewing on Hawking very slowly… meanwhile I shall put my anti-multiverse blast on my site…

So here goes!

Prof. Hawking

Professor Stephen William Hawking was born in 1942 in Oxford, England.  His own website has a nice summary of his life which may be read here.  There is a huge amount that could be written about this most amazing man.  His book A Brief History of Time has sold in the millions which for a man who deals with some pretty big personal challenges, is no small feat.  Here’s a relatively recent talk (2008) from TED2008,

But like the Hugh Everett posting, I wanted to draw your attention to the 48 minute programme, originally from the BBC Horizon series, that explores some of the challenges that are starting to appear to Hawking’s long-held theories about the start of the universe.

The film may be watched from here.

Beautiful minds; Hugh Everett

Two fascinating films about two very beautiful minds, Hugh Everett III and Stephen Hawking.

Hugh Everett III

A documentary on PBS entitled Parallel World, Parallel Lives traces in a deeply personal way, the efforts of the son of Hugh Everett, Mark Oliver Everett, to find out more about his father, who died in 1982, just 51 years old.  Mark Everett is an accomplished musician and much of his music makes it onto the soundtrack of the film. Here’s a brief extract from an article from Scientific American.

Hugh Everett III

Hugh Everett III was a brilliant mathematician, an iconoclastic quantum theorist and, later, a successful defense contractor with access to the nation’s most sensitive military secrets. He introduced a new conception of reality to physics and influenced the course of world history at a time when nuclear Armageddon loomed large. To science-fiction aficionados, he remains a folk hero: the man who invented a quantum theory of multiple universes. To his children, he was someone else again: an emotionally unavailable father; “a lump of furniture sitting at the dining room table,” cigarette in hand.

Here’s a taste of the film from YouTube.

But you may prefer to watch the whole programme, courtesy of Top Documentary Films.

A fascinating programme and one which shows great courage and bravery from Mark Everett in dealing with his memories and emotions about a brilliant but emotionally flawed father.

Thursday, Stephen Hawking.

What is Reality?

Things are never quite what we seem!

There’s that wonderful quote from American comedian, Woody Allen, “What if everything is an illusion and nothing exists? In that case, I definitely overpaid for my carpet.

But that quote may not be as silly as it first appears if I made sense of a programme  that we watched recently.  That was a documentary broadcast by the BBC under their fabulous science series known as Horizon.  As an aside, the range of programmes covered over the years under the Horizon banner is fantastic as this web page from March 2008 demonstrates.  An in-depth history of this BBC series is available on WikiPedia and the ‘Home’ page of the current Horizon website is here.

Anyway, back to this particular programme, What is Reality?  Rather than me natter on about a subject that I don’t understand, despite being captivated by it, let me allow you to watch the programme courtesy of YouTube!  Here is the first half of the programme split into two YouTube videos; the last half will be posted tomorrow.

Do yourself a favour and settle down to watch them undisturbed – as the programme says you may never look at the world around you in quite the same way again!

You have been warned!

 

David Bohm and the Implicate Order

I was much taken by Patrice’s guest post of yesterday and have managed a short break from the travails of my Master’s degree to post an article by David Pratt, that has been part of my research.  Jon.

David Bohm and the Implicate Order

By David Pratt
David Bohm

The death of David Bohm on 27 October 1992 is a great loss not only for the physics community but for all those interested in the philosophical implications of modern science. David Bohm was one of the most distinguished theoretical physicists of his generation, and a fearless challenger of scientific orthodoxy. His interests and influence extended far beyond physics and embraced biology, psychology, philosophy, religion, art, and the future of society. Underlying his innovative approach to many different issues was the fundamental idea that beyond the visible, tangible world there lies a deeper, implicate order of undivided wholeness.

David Bohm was born in Wilkes-Barre, Pennsylvania, in 1917. He became interested in science at an early age, and as a young boy invented a dripless teapot, and his father, a successful businessman, urged him to try to make a profit on the idea. But after learning that the first step was to conduct a door-to-door survey to test market demand, his interest in business waned and he decided to become a theoretical physicist instead.

In the 1930s he attended Pennsylvania State College where he became deeply interested in quantum physics, the physics of the subatomic realm. After graduating, he attended the University of California, Berkeley. While there he worked at the Lawrence Radiation Laboratory where, after receiving his doctorate in 1943, he began what was to become his landmark work on plasmas (a plasma is a gas containing a high density of electrons and positive ions). Bohm was surprised to find that once electrons were in a plasma, they stopped behaving like individuals and started behaving as if they were part of a larger and interconnected whole. He later remarked that he frequently had the impression that the sea of electrons was in some sense alive.

In 1947 Bohm took up the post of assistant professor at Princeton University, where he extended his research to the study of electrons in metals. Once again the seemingly haphazard movements of individual electrons managed to produce highly organized overall effects. Bohm’s innovative work in this area established his reputation as a theoretical physicist.

In 1951 Bohm wrote a classic textbook entitled Quantum Theory, in which he presented a clear account of the orthodox, Copenhagen interpretation of quantum physics. The Copenhagen interpretation was formulated mainly by Niels Bohr and Werner Heisenberg in the 1920s and is still highly influential today. But even before the book was published, Bohm began to have doubts about the assumptions underlying the conventional approach. He had difficulty accepting that subatomic particles had no objective existence and took on definite properties only when physicists tried to observe and measure them. He also had difficulty believing that the quantum world was characterized by absolute indeterminism and chance, and that things just happened for no reason whatsoever. He began to suspect that there might be deeper causes behind the apparently random and crazy nature of the subatomic world.

Bohm sent copies of his textbook to Bohr and Einstein. Bohr did not respond, but Einstein phoned him to say that he wanted to discuss it with him. In the first of what was to turn into a six-month series of spirited conversations, Einstein enthusiastically told Bohm that he had never seen quantum theory presented so clearly, and admitted that he was just as dissatisfied with the orthodox approach as Bohm was. They both admired quantum theory’s ability to predict phenomena, but could not accept that it was complete and that it was impossible to arrive at any clearer understanding of what was going on in the quantum realm.

It was while writing Quantum Theory that Bohm came into conflict with McCarthyism. He was called upon to appear before the Un-American Activities Committee in order to testify against colleagues and associates. Ever a man of principle, he refused. The result was that when his contract at Princeton expired, he was unable to obtain a job in the USA. He moved first to Brazil, then to Israel, and finally to Britain in 1957, where he worked first at Bristol University and later as Professor of Theoretical Physics at Birkbeck College, University of London, until his retirement in 1987. Bohm will be remembered above all for two radical scientific theories: the causal interpretation of quantum physics, and the theory of the implicate order and undivided wholeness.

In 1952, the year after his discussions with Einstein, Bohm published two papers sketching what later came to be called the causal interpretation of quantum theory which, he said, “opens the door for the creative operation of underlying, and yet subtler, levels of reality.” (David Bohm and F. David Peat, Science, Order & Creativity, Bantam Books, New York, 1987, p. 88.) He continued to elaborate and refine his ideas until the end of his life. In his view, subatomic particles such as electrons are not simple, structureless particles, but highly complex, dynamic entities. He rejects the view that their motion is fundamentally uncertain or ambiguous; they follow a precise path, but one which is determined not only by conventional physical forces but also by a more subtle force which he calls the quantum potential.The quantum potential guides the motion of particles by providing “active information” about the whole environment. Bohm gives the analogy of a ship being guided by radar signals: the radar carries information from all around and guides the ship by giving form to the movement produced by the much greater but unformed power of its engines.

The quantum potential pervades all space and provides direct connections between quantum systems. In 1959 Bohm and a young research student Yakir Aharonov discovered an important example of quantum interconnectedness. They found that in certain circumstances electrons are able to “feel” the presence of a nearby magnetic field even though they are traveling in regions of space where the field strength is zero. This phenomenon is now known as the Aharonov-Bohm (AB) effect, and when the discovery was first announced many physicists reacted with disbelief. Even today, despite confirmation of the effect in numerous experiments, papers still occasionally appear arguing that it does not exist.

In 1982 a remarkable experiment to test quantum interconnectedness was performed by a research team led by physicist Alain Aspect in Paris. The original idea was contained in a thought experiment (also known as the “EPR paradox”) proposed in 1935 by Albert Einstein, Boris Podolsky, and Nathan Rosen, but much of the later theoretical groundwork was laid by David Bohm and one of his enthusiastic supporters, John Bell of CERN, the physics research center near Geneva. The results of the experiment clearly showed that subatomic particles that are far apart are able to communicate in ways that cannot be explained by the transfer of physical signals traveling at or slower than the speed of light. Many physicists, including Bohm, regard these “nonlocal” connections as absolutely instantaneous. An alternative view is that they involve subtler, nonphysical energies traveling faster than light, but this view has few adherents since most physicists still believe that nothing-can exceed the speed of light.

The causal interpretation of quantum theory initially met with indifference or hostility from other physicists, who did not take kindly to Bohm’s powerful challenge to the common consensus. In recent years, however, the theory has been gaining increasing “respectability.” Bohm’s approach is capable of being developed in different directions. For instance, a number of physicists, including Jean-Paul Vigier and several other physicists at the Institut Henri Poincaré in France, explain the quantum potential in terms of fluctuations in an underlying ether.

In the 1960s Bohm began to take a closer look at the notion of order. One day he saw a device on a television program that immediately fired his imagination. It consisted of two concentric glass cylinders, the space between them being filled with glycerin, a highly viscous fluid. If a droplet of ink is placed in the fluid and the outer cylinder is turned, the droplet is drawn out into a thread that eventually becomes so thin that it disappears from view; the ink particles are enfolded into the glycerin. But if the cylinder is then turned in the opposite direction, the thread-form reappears and rebecomes a droplet; the droplet is unfolded again. Bohm realized that when the ink was diffused through the glycerin it was not a state of “disorder” but possessed a hidden, or nonmanifest, order.

In Bohm’s view, all the separate objects, entities, structures, and events in the visible or explicate world around us are relatively autonomous, stable, and temporary “subtotalities” derived from a deeper, implicate order of unbroken wholeness. Bohm gives the analogy of a flowing stream:

On this stream, one may see an ever-changing pattern of vortices, ripples, waves, splashes, etc., which evidently have no independent existence as such. Rather, they are abstracted from the flowing movement, arising and vanishing in the total process of the flow. Such transitory subsistence as may be possessed by these abstracted forms implies only a relative independence or autonomy of behaviour, rather than absolutely independent existence as ultimate substances.

(David Bohm, Wholeness and the Implicate Order, Routledge & Kegan Paul, London, Boston, 1980, p. 48.)

We must learn to view everything as part of “Undivided Wholeness in Flowing Movement.” (Ibid., p. 11.)

Another metaphor Bohm uses to illustrate the implicate order is that of the hologram. To make a hologram a laser light is split into two beams, one of which is reflected off an object onto a photographic plate where it interferes with the second beam. The complex swirls of the interference pattern recorded on the photographic plate appear meaningless and disordered to the naked eye. But like the ink drop dispersed in the glycerin, the pattern possesses a hidden or enfolded order, for when illuminated with laser light it produces a three-dimensional image of the original object, which can be viewed from any angle. A remarkable feature of a hologram is that if a holographic film is cut into pieces, each piece produces an image of the whole object, though the smaller the piece the hazier the image. Clearly the form and structure of the entire object are encoded within each region of the photographic record.

Bohm suggests that the whole universe can be thought of as a kind of giant, flowing hologram, or holomovement, in which a total order is contained, in some implicit sense, in each region of space and time. The explicate order is a projection from higher dimensional levels of reality, and the apparent stability and solidity of the objects and entities composing it are generated and sustained by a ceaseless process of enfoldment and unfoldment, for subatomic particles are constantly dissolving into the implicate order and then recrystallizing.

The quantum potential postulated in the causal interpretation corresponds to the implicate order. But Bohm suggests that the quantum potential is itself organized and guided by a superquantum potential, representing a second implicate order, or superimplicate order. Indeed he proposes that there may be an infinite series, and perhaps hierarchies, of implicate (or “generative”) orders, some of which form relatively closed loops and some of which do not. Higher implicate orders organize the lower ones, which in turn influence the higher.

Bohm believes that life and consciousness are enfolded deep in the generative order and are therefore present in varying degrees of unfoldment in all matter, including supposedly “inanimate” matter such as electrons or plasmas. He suggests that there is a “protointelligence” in matter, so that new evolutionary developments do not emerge in a random fashion but creatively as relatively integrated wholes from implicate levels of reality. The mystical connotations of Bohm’s ideas are underlined by his remark that the implicate domain “could equally well be called Idealism, Spirit, Consciousness. The separation of the two — matter and spirit — is an abstraction. The ground is always one.” (Quoted in Michael Talbot, The Holographic Universe, HarperCollins, New York, 1991, p. 271.)

As with all truly great thinkers, David Bohm’s philosophical ideas found expression in his character and way of life. His students and colleagues describe him as totally unselfish and non-competitive, always ready to share his latest thoughts with others, always open to fresh ideas, and single-mindedly devoted to a calm but passionate search into the nature of reality. In the words of one of his former students, “He can only be characterized as a secular saint.” (B. Hiley & F. David Peat eds., Quantum Implications: Essays in Honour of David Bohm, Routledge & Kegan Paul, London, 1987, p. 48.)

Bohm believed that the general tendency for individuals, nations, races, social groups, etc., to see one another as fundamentally different and separate was a major source of conflict in the world. It was his hope that one day people would come to recognize the essential interrelatedness of all things and would join together to build a more holistic and harmonious world. What better tribute to David Bohm’s life and work than to take this message to heart and make the ideal of universal brotherhood the keynote of our lives.

(Reprinted from Sunrise magazine, February/March 1993. Copyright © 1993 by Theosophical University Press)

And for a fascinating insight into Bohm and his beautiful brain, watch this:

By Jon Lavin