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What could be weirder than quantum mechanics? This physics framework is responsible for any number of bizarre phenomena—theoretical cats that are simultaneously dead and alive, particles kilometers apart that can nonetheless communicate instantaneously, and indecisive photons that somehow go two directions at once.
But it is also responsible for the technological advances that make modern life possible. Without quantum mechanics there would be no transistor, and hence no personal computer; no laser, and hence no Blu-ray players. James Kakalios, a physics professor at the University of Minnesota, wants people to understand how much quantum mechanics influences our everyday lives—but to do so people must first understand quantum mechanics.
Kakalios sets out to tackle both tasks in The Amazing Story of Quantum Mechanics (Gotham Books, 2010), an accessible, mostly math-free treatment of one of the most complex topics in science. To keep things lively, the author intersperses illustrations and analogies from Buck Rogers stories and other classic science fiction tales. We spoke to Kakalios about his new book, what quantum mechanics has made possible, and how early sci-fi visions of the future compare with the present as we know it.
[An edited transcript of the interview follows.]
Is the purpose of this book to expose this world of quantum mechanics that people find so mysterious and point out that it's everywhere?
That's right. In fact, the introduction is called, "Quantum physics? You're soaking in it!"
There are many excellent books about the history and the philosophical underpinnings of quantum mechanics. But there didn't seem to be many that talked about how useful quantum mechanics is. Yes, the science has weird ideas and it can be confusing. But one of the most amazing things about quantum mechanics is that you can use it correctly and productively even if you're confused by it.
I present in the introduction what I call a "workingman's view" of quantum mechanics and show how if you accept on faith three weird ideas—that light is a photon; that matter has a wavelength nature associated with its motion; and that everything, light and matter, has an intrinsic angular momentum or spin that can only have discrete values—it turns out that you can then see how lasers work. You can see how a transistor works or your computer hard drive or magnetic resonance imaging—a host of technologies that we take for granted that pretty much define our life.
There were computers before the transistor; they used vacuum tubes as logic elements. To make a more powerful computer meant that you had to have more vacuum tubes. They were big, they generated a lot of heat, they were fragile. You had to make the room and the computer very large. And so if you used vacuum tubes, only the government and a few large corporations would have the most powerful computers. You wouldn't have millions of them across the country. There would be no reason to hook them all together into an Internet, and there would be no World Wide Web.
The beautiful aspect to this is the scientists who developed this were not trying to make a cell phone; they were not trying to invent a CD player. If you went to Schrödinger in 1926 and said, "Nice equation, Erwin. What's it good for?" He's not going to say, "Well, if you want to store music in a compact digital format..."
But without the curiosity-driven understanding of how atoms behave, how they interact with each other, and how they interact with light, the world we live in would be profoundly different.
So, to take one example, how does quantum mechanics make the laser possible?
One of the most basic consequences of quantum mechanics is that there is a wave associated with the motion of all matter, including electrons in an atom. Schrödinger came up with an equation that said: "You tell me the forces acting on the electron, and I can tell you what its wave is doing at any point in space and time." And Max Born said that by manipulating this wave function that Schrödinger developed, you could tell the probability of finding the electron at any point in space and time. From that, it turns out that the electron can only have certain discrete energies inside an atom. This had been discovered experimentally; this is the source of the famous line spectrum that atoms exhibit and that accounts for why neon lights are red whereas sodium streetlights have a yellow tinge. It has to do with the line spectra of their respective elements.
But to have an actual understanding of where these discrete energies come from—that electrons and atoms can only have certain energies and no other—is one of the most amazing things about quantum mechanics. It's as though you are driving a car on a racetrack and you are only allowed to go in multiples of 10 miles per hour. When you take that and you bring many atoms together, all of those energies broaden out into a band of possible energies.
The analogy that I use is you have an auditorium with an orchestra below and a balcony above. That means to go from the orchestra to the balcony you have to absorb some energy to be promoted from the orchestra to the balcony. Now if every seat in the orchestra is filled, and you want to move from one seat to another, you can't go anywhere unless you absorb some energy and are promoted up into the balcony, where there are empty seats and you can move around. What happens in a laser is you have a little mezzanine right below the balcony. You get promoted up to the balcony but then you fall and you sit in the mezzanine. And eventually, as the mezzanine gets filled up, there's a bunch of empty seats in the orchestra, where you came from.
One person gets pushed out of the mezzanine, and because of the way they talk to each other, they all go at the same time. They release energy as they fall back from the mezzanine into the orchestra, and that energy is in the form of light. Because they are all coming from the same row of seats in the mezzanine, all the light has exactly the same color. Since they all went at the same time, they are all coherently in phase. And if you have a lot of them up in the mezzanine, you can have a very high intensity beam of single-color light. That's a laser.
See what we're tweeting about
23 Comments
Add CommentIt seems like we should develop Quantum Mechanics into an addiction. That would be an addiction we all can live with comfortably.
Reply | Report Abuse | Link to thisGreat article by the way.
"[But] it is also responsible for the technological advances that make modern life possible. Without quantum mechanics there would be no transistor, and hence no personal computer; no laser, and hence no Blu-ray players." This statement, which is already a truism, should be backed with some explanation on how quantum theory is applied in technology. That would merit a Nobel in physics!
Reply | Report Abuse | Link to thisThe sour truth about quantum is told by Roger Penrose in "The Road To Reality", but it will take a while for scientist to digest it.
Now, the day superluminal communication is realized and quantum computers work, well, that day we should open the champagne. Until then we should refrain from ridiculous statements.
Regardless of any theater, light emitting energies cannot be measured
Reply | Report Abuse | Link to thisreally.
Regardless of any theater, light emitting energies cannot be measured
Reply | Report Abuse | Link to thisreally.
An article to be enjoyed. Anything that exposes New Age fantasies is worth introducing to our more gullible friends.
Reply | Report Abuse | Link to thisI'm just a general reader, although physics is one of my favorite subjects. I gave up majoring in it as an undergrad, switched to Linguistics, and some years later did my grad work in Medieval Studies. That's not so far fetched as you'd think, when you consider the amazing progress in mechanical engineering, optics and mathematics in the later Middle Ages from East Asia through India to Western Europe.
When I was about 22, not long out of college, I read a new book by physicist Banesh Hoffman, THE STRANGE STORY OF THE QUANTUM. Forget the romantic title. It's very well-written, a great introduction. I admired Hoffman's book so much I went through 3 copies--since I kept lending it to friends who'd forget to return it.
Of course it's been outdated for years. I've been trying to keep up with every area of science in SCIAM, sometimes find the quantum physics features over my head, so am looking forward to this new Kakalios book! Thanks for publishing a very readable review and commentary.
The article states:
Reply | Report Abuse | Link to this"...that light is a photon; that matter has a wavelength nature associated with its motion; and that everything, light and matter, has an intrinsic angular momentum or spin that can only have discrete values..."
Perhaps I'm wrong, but I think it's more clear and precise to state that:
- matter, in addition to its stationary particle state, has a wave state that produces all of its motion through self-propagation
- light has a particle state that can be detected through absorption of its wave state momentum
- both wave and particle state manifestations exhibit an intrinsic angular momentum or spin characteristic property that can only have discrete values
Nicely done article, although I think the transistor was invented in Texas to make compact calculators but first mass produced in Japan to make inexpensive portable radios.
More than the few physicists that have produced breakthrough fundamental discoveries, there's been an enormous amount of extremely creative work done by countless unrecognized engineers and programmers to produce the highly advanced critical technology that presumedly allows the more productive use of our valuable time.
If I remember correctly, the guy that invented the transistor died pennyless, of a disease that he could not afford the treatment for. Isn't capitalism wonderful?
Reply | Report Abuse | Link to thisNice review and I will be aquiring the book when I can afford to.
Carlos,
Reply | Report Abuse | Link to thisDo you 1) not accept that the laser and the transistor work on quantum mechanical principles? Or do you 2) not accept that a detailed understanding of quantum mechanics made these devices possible?
If 1), you should take a class on these devices. If 2), I'll grant you that quantum effects were observed before they were understood. It is possible to build technology without fully understanding it. However, it is extremely difficult to improve technology without understanding it. You would not have a DVD player if the only lasers out there were 1960s ruby lasers. Quantum mechanics is used when designing the structure and materials of lasers and transistors. As far as Penrose goes, I have his book and I have no idea what you mean by the "sour truth" about quantum mechanics. The fact that QM (like all theories) has limitations doesn't make it useless, and Penrose never suggests otherwise.
C, Q: Do you 1) not accept that the laser and the transistor work on quantum mechanical principles? Or do you 2) not accept that a detailed understanding of quantum mechanics made these devices possible?
Reply | Report Abuse | Link to thisIf 1), you should take a class on these devices. If 2), I'll grant you that quantum effects were observed before they were understood. It is possible to build technology without fully understanding it. However, it is extremely difficult to improve technology without understanding it.
Nobody in Bell's Lab (which invented the transistor) knew a thing about Quantum Mechanics! After the invention was done theoretical physicists created "Solid State" curriculum to "adapt" the very adaptable Quantum Theory to the new facts. As for the "laser" Quantum theorists
predicted the "maser" and wasted a lot of taxpayers money. Meanwhile technologists developed the laser into what is today's products.
Generally well put - thanks.
Reply | Report Abuse | Link to thisMy vague recollection was that Texas Instruments invented the transistor, so I consulted wikipedia. It states that Physicist Julius Edgar Lilienfeld filed the first patent for a transistor in Canada in 1925. Bell Labs patented the the transistor in the U.S. in 1947. The first silicon transistor was produced by Texas Instruments in 1954. It's worth a read.
I think though that you are essentially correct in asserting that quantum theory has had little if anything to do with technological developments - most often just the opposite.
In regards to VLSI electronics, including computer chips, one predicted quantum effect that has come into play is the tunneling of electrons through silicon substrate. I'm not a processor designer and can't say if this phenomena is employed in the design of processors, but it is the limiting factor in circuit miniaturization, as device electron leakage produces processing errors and device EM leakage producing heating and power losses.
I've been reading that quantum computing is just around the corner for decades, it seems...
Instantaneous information transport is possible even in classical mechanics. In car engines the cam shaft is doing that by synchronizing valves instantaneously. Of course, the cam shaft has to be made of very stiff material. Steel will be good but not good enough. Silicon would be better. Some physicists will say that instantaneous information transfer would violate special relativity. Special relativity is known to be incompatible with quantum mechanics as well as with classical physics. So let's forget about special relativity, see Sciam March 2009 issue.
Reply | Report Abuse | Link to thisQuantum Mechanics as understood today is a device of stupid scientists who cannot think beyond Differential Calculus posted by Newton more than 300 years ago.
Reply | Report Abuse | Link to thisMathemaics exists beyond this. Numbering Differential Calculus at level four, we go right upto level twelve. But you do not have to go that high. Even at level five, just one above what these idiots consider upper limit, you can see that “Uncertainty Principle” is an illusion created by limitations of Differential Calculus.
With this level operations you can always re-format any Diffraction experiment into variations in dielectric value in space so that initial radiation pattern of photons gets changed into the diffraction pattern with sharp trajectories of every one of the photons exactly defined so that the location and momentum (also velocity) of the photon can be exactly computed.
What did you say ‘what about matter waves?’ Only an idiot can think of matter waves as scalar, as do these Qantum fans. Matter is all electromagnetic, else it would not obey Lorentz Transformation (read Einstein’s Relativity Theory), which is just Maxwell’s equations in a different format. So go ahead and laud these Quantum idiots who do not even know that. After all Einstein was correct. “GOD does not play dice.”
Dr. R. R. Karnik
ravi@karnik.com
rrkarnik:
Reply | Report Abuse | Link to thisQuantum Mechanics explains why electrons emit microwaves from Gunn effect semiconductors such as gallium arsenide. Why the photoelectric effect is correct as Albert Einstein has said in 1905. Special relativity, however, is wrong as the Lorentz transformation equations are illogical and as Michelson and his student Gale have shown by measuring the earths rotation using light beams. Einstein was a good scientists but relativity theory is wrong. The Nobel Committee knew that and therefore gave Einstein the Price for Quantum effects. The Schroedinger equation is the starting equation in all textbooks for QM.
Dear Thim
Reply | Report Abuse | Link to thisFirst I agree with you on Special Relativity Theory being wrong. You do not seem to know General Relativity Theory, but it is also wrong. I will welcome criticism even on this.
Lorentz’s work is just re-formatting of Maxwell’s Theory. If you think that Maxwell is wrong then I do not know what to think of you, being an Electrical Engineer and having used his theory for everything.
What you are praising in arsenide excited states and photo electric effects is the Diffraction Phenomenon, in which exact motions, that is exact locations and momentum (velocity) of photons and electrons are not even allowed, in Quantum Mechanics, due to stupid “Uncertainty Principle”. So explanation is out of question, only some “Thumb Rule guesses are stated”, which may or may not be correct, which is all that Quantum Mechanics is good for, which is my point. We need Mathematics higher than Differential Calculus, which can solve an infinite series of Differential Expressions in one go, which is my point. It can be demonstrated that, with Calculus at level four, these levels can go up to twelve.
The very fact that QM starts with Schroedinger equation which treats matter waves as Scalar is proof itself that QM is no good.
Dr. R. R. Karnik
ravi@karnik.com
Dear RRKARNIK:
Reply | Report Abuse | Link to thiswell, Maxwell's equation work quite well but Feynman had tried to modify them as they fail in certain applications. As a consequence of this Quantum Electrodynamics have been invented by Feynman. I am still using Maxwell's equations successfully.
Solutions of Schroedinger's equation predict for electrons particle-waves in semiconductors thereby forming conduction band valleys in which electrons experience differential negative conductance. The consequence of this are microwaves emitted from those semiconductors such as GaAs and InP which have been measured.
So the Schroedinger equation cannot be so bad as you are saying.
The Lorentz Transformations are much worse and illogical but the inventor of those did not recognize that and rather called Quantum Mechanics "Spooky Actions" or thought that God does not play dice and more similar nonsense.
jtdwyer's:
Reply | Report Abuse | Link to thishow can you say: "Nobody at Bell Labs used QM". I did
use them and found that due to quantum mechanical laws gallium arsenide bulk amplifiers worked well at microwave frequencies so those patended devices had been used by the United State Defense Department!
Reply | Report Abuse | Link to thisDear Thim
I do not know what Feynman did in Electrodynamics, I have high regards for him, but I too have a version of Maxwell’s Equations that give Vector matter waves just like Electromagnetic waves and can be mapped exactly, responding to variations in dielectric values, which what this Gravity business is.
I am sure that Feynman’s version does not give exact location and momentum of photons at every point in its path from initial emission to final absorption. He is not that bad.
This prediction business is the bane of QM, as it prevents working out exact solutions, which can be verified, and generates wide speculations, which we call power without responsibility. Yes, you do hit the targets once in a while but remember that 9 out of 10 semiconductor wafer manufacturers went broke. So there is an exact solution that is blocked out by these stupid scalar concepts of matter waves. Making money is not development of science, finding exact solutions is.
Deriving Lorentz Transformation without the rest of Electrodynamics is stupid and I am all with you for condemning Einstein for that, but working with retarded vector potentials is satisfying and when you do it on a moving platform like a train, these transformations are very handy. The probability business in QM is merely using the properties of binomial coefficients, the numbers are not even complex. That is how businessmen make money, they have highly paid executives just doing that. But that is not science, getting exact solutions is. Unless this “Uncertainty Principle” is purged QM will never become Science. I do not believe in GOD , but universe does not run on throw of dice and what you have stated about it, itself is a condemnation of QM.
Remember that Physics is an exact science. Electron motions inside a solid can be modeled exactly. In fact I de-bunk General Relativity by computing the product of momentum and velocity of each of these electrons and claim that this is attracted in gravity and when this is reduces as when tensile stress is applied, the downward force in gravity gets reduced, meaning levitation of tensile stress volume, which effect does not exist in General Relativity. This QM is thoroughly useless for this proof.
Another application is the so called “Spin Interactions”. With scalar matter waves their polarization is not possible, which forecloses computation of these spin effects using polarization. They have invented the non-existent “Spinor”, and instead of tracking the variations in diffraction patterns, due to polarization and measuring and converting them into attractive and repulsive forces, just guessed backwards from some average measurements what they should be. Einstein failed to develop his Unified Field Theory because, stupid as he was, he knew from personal experience that stupidity was infinite, he actually, like you, believed in QM theory, which using scalar matter waves did not give him the right directions.
So go ahead and stick to QM, you are not going to go forward in science that way.
Dr. R. R. Karnik
ravi@karnik.com
I agree with you, RR Karnik, that QM is a tool, but it is a useful tool. It explains why electrons behave as they do in semiconductors. Ohm's law could not do that. Ohm's law is useful to explain currents in copper wires. Approximately. Not precise. But useful. QM is much better. How would you explain conduction and valence bands in semiconductors? How would you explain why LED's and LASER diodes work? However, no theory is perfect.
Reply | Report Abuse | Link to thisDear Thim
Reply | Report Abuse | Link to thisAll that you mention, seemingly impossible can be done, exactly and even the momentum and velocity of all these electrons can be computed, which according to QM is impossible. Of course no theory can ever be perfect, that is the first principle of “advaita brahma”, which is essence of basic science.
If superstitions, called “avidyaa” in Sanskrit, were not useful and did not explain what the believers want they will simply disappear. In “advaita brahma” even concept og GOD is “avidyaa”.
My grouse with both Relativity and QM is that they block the future scientific free thinking, which is a greater loss to science than what the petty successes gain. With these two theories the mind of scientists is no longer open. They do not even publish your treatises if you contradict these theories.
That is all my point. QM does more bad than good.
Dr. R. R. Karnik
ravi@karnik.com
I hope the book is better than this article.
Reply | Report Abuse | Link to thisWhy use meaningless analogies, using totally factitious situations like the analogy with auditorium and a balcony above. It explains nothing about laser, nothing about how/why they work. And it gives less intuition then some straight descriptions.
Then, so much space used to convince us about obvious, that original inventors often don't know the future use of invention. You mean like the original inventors of the wheel didn't foresee it's use in Space Shuttle or Wheel of Fortune show? What a shock...
Well stated. I view everything as a kind of duality between balance and imbalance. Any quantum state is a state of balance. Any phenomena discribed or percieved as a wave is the propagation of balance as a function of time. The former is percieved in the moment, the later over a time period.
Reply | Report Abuse | Link to thisThe history of the artificial is built on chance observation and discoveries. We put rock on rock and notice some methods of doing that are more stable than others. Today we build massive skyscrapers yet we still really do not understand what gravity is. We build clocks that are ever more precise and sophisticated yet we still do not really understand what time is.
Reply | Report Abuse | Link to thisWe build mathematical models that enable us to predict cause-effect reliably. Our growth in understanding and science in general is a growth in understanding "how" things behave in the natural world. Science doesn't really involve itself with "why".