Tag Αρχεία: Richard Feynman

Richard Feynman — Πόσο μπορούμε να ξέρετε?

Θα ανοίξουμε τα μάτια μας, βλέπουμε τον κόσμο, διακρίνουμε μοτίβα. Εμείς θεωρούμε, επισημοποιήσει; χρησιμοποιούμε και ορθολογισμού και τα μαθηματικά για να κατανοήσει και να περιγράψει τα πάντα. Πόσο μπορούμε πραγματικά να γνωρίζουμε, αν?

Για να δείξουμε τι εννοώ, επιτρέψτε μου να χρησιμοποιήσω μια αναλογία. Μακάρι να είχα τη φαντασία για να καταλήξει με το, αλλά ήταν ο Richard Feynman, που έκανε. Ήταν, από τον τρόπο, αρκετά ιδιόμορφη να συγκρίνετε Φυσική με το σεξ.

Συνεχίστε την ανάγνωση

Βλέποντας και Πιστεύοντας

Όταν ανοίγουμε τα μάτια μας και να δούμε κάποια πράγματα, βλέπουμε αυτό το καταραμένο πράγμα. Τι θα μπορούσε να είναι πιο προφανές από ότι, δεξιά? Ας πούμε ότι έχετε κοιτάζοντας το σκυλί σας. Αυτό που βλέπετε είναι πραγματικά το σκυλί σας, γιατί, αν θέλετε, μπορείτε να φτάσετε έξω και να αγγίξει το. Είναι γαβγίζει, και μπορείτε να ακούσετε το υφάδι. Αν βρωμάει λίγο, μπορείτε να μυρίσετε. Όλα αυτά τα επιπλέον αντιληπτικές στοιχεία επιβεβαιώνουν την πεποίθησή σας ότι αυτό που βλέπουμε είναι ο σκύλος σας. Άμεσα. Δεν υπάρχουν ερωτήσεις.

Φυσικά, δουλειά μου σε αυτό το blog είναι να κάνετε ερωτήσεις, και αμφιβολίες καστ. Καταρχάς, βλέποντας και αγγίζοντας φαίνεται να είναι λίγο διαφορετική από την ακοή και όσφρηση. Δεν ακούω αυστηρά γαυγίζει ο σκύλος σας, να ακούσετε τον ήχο της. Παρομοίως, δεν το μυρίζουν άμεσα, μυρίζεις τη μυρωδιά, το χημικό μονοπάτι ο σκύλος έχει μείνει στον αέρα. Ακρόαση και μυρωδιά είναι τρεις αντιλήψεις χώρα — ο σκύλος παράγει ήχο / οσμή, ο ήχος / οσμή ταξιδεύει σε σας, αντιλαμβάνεστε τον ήχο / οσμή.

Αλλά βλέποντας (ή αγγίζοντας) Είναι ένα πράγμα δύο θέση — ο σκύλος εκεί, και εδώ το αντιλαμβανόμαστε άμεσα. Γιατί είναι ότι? Γιατί έχουμε την αίσθηση ότι όταν δει ή να αγγίξει κάτι, θα το αισθανθούν άμεσα? Αυτή η πίστη στην αντιληπτική ακρίβεια του τι βλέπουμε ονομάζεται αφελής ρεαλισμός. Εμείς φυσικά γνωρίζουμε ότι βλέπουμε περιλαμβάνει το φως (το ίδιο κάνει και συγκινητικό, αλλά σε ένα πολύ πιο περίπλοκο τρόπο), αυτό που βλέπουμε είναι το φως που αντανακλάται από ένα αντικείμενο και ούτω καθεξής. Είναι, όντως, δεν διαφέρει από κάτι ακοής. Αλλά αυτή η γνώση του μηχανισμού των seeing δεν αλλοιώνει τη φυσική μας, κοινή λογική άποψη ότι αυτό που βλέπουμε είναι αυτό που είναι εκεί έξω. Βλέποντας αυτή πιστεύεται.

Συμπερασματικά, από την αφελή εκδοχή είναι ο επιστημονικός ρεαλισμός, η οποία υποστηρίζει ότι οι επιστημονικές ιδέες μας είναι επίσης πραγματική, eventhough δεν μπορεί να αντιληφθεί τους άμεσα. Έτσι, τα άτομα είναι πραγματικές. Τα ηλεκτρόνια είναι πραγματικές. Τα κουάρκ είναι πραγματικές. Τα περισσότερα από τα καλύτερα επιστήμονες μας έξω υπήρξαν επιφυλακτικοί σχετικά με αυτό το extraploation με την αντίληψη μας για το τι είναι πραγματικό. Einstein, ίσως το καλύτερο από τους, υποψία ότι ακόμη χώρος και ο χρόνος μπορεί να μην είναι πραγματικός. Φάινμαν και Gell-Mann, μετά την ανάπτυξη των θεωριών για τα ηλεκτρόνια και τα κουάρκ, εξέφρασαν την άποψη ότι τα ηλεκτρόνια και τα κουάρκ μπορεί να είναι μαθηματικές δομές και όχι πραγματικές οντότητες.

What I am inviting you to do here is to go beyond the skepticism of Feynman and Gell-Mann, and delve into Einstein’s words — space and time are modes by which we think, not conditions in which we live. The sense of space is so real to us that we think of everything else as interactions taking place in the arena of space (and time). But space itself is the experience corresponding to the electrical signals generated by the light hitting your retina. It is a perceptual construct, much like the tonality of the sound you hear when air pressure waves hit your ear drums. Our adoption of naive realism results in our complete trust in the three dimensional space view. And since the world is created (in our brain as perceptual constructs) based on light, its speed becomes an all important constant in our world. And since speed mixes space and time, a better description is found in a four dimensional Minkowski geometry. But all these descriptions are based on perceptual experiences and therefore unreal in some sense.

I know the description above is highly circular — I talked about space being a mental construct created by light traveling through, get this, space. And when I speak of its speed, naturally, I’m talking about distance in space divided by time, and positing as the basis for the space-time mixing. This circularity makes my description less than clear and convincing. But the difficulty goes deeper than that. You see, all we have is this cognitive construct of space and time. We can describe objects and events only in terms of these constructs even when we know that they are only cognitive representations of sensory signals. Our language doesn’t go beyond that. Well, it does, but then we will be talking the language, for instance, of Advaita, calling the constructs Maya and the causes behind them Brahman, which stays unknowable. Or, we will be using some other parallel descriptions. These descriptions may be profound, wise and accurate. But ultimately, they are also useless.

But if philosophy is your thing, the discussions of cognitive constructs and unknown causations are not at all useless. Philosophy of physics happens to be my thing, and so I ask myself — what if I assume the unknown physical causes exist in a world similar to our perceptual construct? I could then propagate the causes through the process of perception and figure out what the construct should look like. I know, it sounds a bit complex, but it is something that we do all the time. We know, for instance, that the stars that we see in the night sky are not really there — we are seeing them the way they were a few (or a few million or billion) years ago because the light from them takes a long time to reach us. Physicists also know that the perceived motion of celestial objects also need to be corrected for these light-travel-time effects.

In fact, Einstein used the light travel time effects as the basis for deriving his special theory of relativity. He then stipulated that space and time behave the way we perceive them, derived using the said light-travel-time effects. This, of course, is based on his deep understanding that space and time are “the modes by which we think,” but also based on the assumption that the the causes behind the modes also are similar to the modes themselves. This depth of thinking is lost on the lesser scientists that came after him. The distinction between the modes of thinking and their causation is also lost, so that space and time have become entities that obey strange rules. Like bent spoons.

Photo by General Press1

Rules of the Game

Richard FeynmanRichard Feynman used to employ the game of chess as a metaphor for the pursuit of physics. Physicists are like uninitiated spectators at a chess match, and they are trying figure out the rules of the game. (He also used sex, but that’s another story.) They observe the moves and try figure out the rules that govern them. Most of the easy ones are soon discovered, but the infrequent and complex ones (such as castling, to use Feynman’s example) are harder to decipher. The chess board is the universe and the players are presumably the Gods. So when Albert Einstein’s Albert Einstein said that he wanted to know God’s thoughts, and that the rest were details, he probably meant he wanted to know the rules and the strategies based on them. Not the actual pattern on the board at any point in time, which was a mere detail.

A remarkable Indian writer and thinker, O. V. Vijayan, also used the metaphor of a chess game to describe the armed strife between India and her sibling neighbor. He said that our too countries were mere pawns in a grand chess game between giant players of the cold war. The players have stopped playing at some point, but the pawns still fight on. What made it eerie (in a Dr. Strangelove sort of way) is the fact that the pawns had huge armies and nuclear weapons. When I first read this article by O. V. Vijayan, his clarity of perspective impressed me tremendously because I knew how difficult it was to see these things even-handedly without the advantage of being outside the country — the media and their public relations tricks make it very difficult, if not impossible. It is all very obvious from the outside, but it takes a genius to see it from within. But O. V. Vijayan’s genius had impressed me even before that, and I have a short story and a thought snippet by him translated and posted on this blog.

Chess is a good metaphor for almost everything in life, with its clear and unbending rules. But it is not the rules themselves that I want to focus on; it is the topology or the pattern that the rules generate. Even before we start a game, we know that there will be an outcome — it is going to be a win, loss or a draw. 1-0, 0-1 or 0.5-0.5. How the game will evolve and who will win is all unknown, but that it will evolve from an opening of four neat rows through a messy mid game and a clear endgame is pretty much given. The topology is pre-ordained by the rules of the game.

A similar set of rules and a consequent topology exists in the corporate world as well. That is the topic of the next post.

Bye Bye Einstein

Starting from his miraculous year of 1905, Einstein has dominated physics with his astonishing insights on space and time, and on mass and gravity. True, there have been other physicists who, with their own brilliance, have shaped and moved modern physics in directions that even Einstein couldn’t have foreseen; and I don’t mean to trivialize neither their intellectual achievements nor our giant leaps in physics and technology. But all of modern physics, even the bizarre reality of quantum mechanics, which Einstein himself couldn’t quite come to terms with, is built on his insights. It is on his shoulders that those who came after him stood for over a century now.

One of the brighter ones among those who came after Einstein cautioned us to guard against our blind faith in the infallibility of old masters. Taking my cue from that insight, I, for one, think that Einstein’s century is behind us now. I know, coming from a non-practicing physicist, who sold his soul to the finance industry, this declaration sounds crazy. Delusional even. But I do have my reasons to see Einstein’s ideas go.

[animation]Let’s start with this picture of a dot flying along a straight line (on the ceiling, so to speak). You are standing at the centre of the line in the bottom (on the floor, that is). If the dot was moving faster than light, how would you see it? Well, you wouldn’t see anything at all until the first ray of light from the dot reaches you. As the animation shows, the first ray will reach you when the dot is somewhere almost directly above you. The next rays you would see actually come from two different points in the line of flight of the dot — one before the first point, and one after. Thus, the way you would see it is, incredible as it may seem to you at first, as one dot appearing out of nowhere and then splitting and moving rather symmetrically away from that point. (It is just that the dot is flying so fast that by the time you get to see it, it is already gone past you, and the rays from both behind and ahead reach you at the same instant in time.Hope that statement makes it clearer, rather than more confusing.).

[animation]Why did I start with this animation of how the illusion of a symmetric object can happen? Well, we see a lot of active symmetric structures in the universe. For instance, look at this picture of Cygnus A. There is a “core” from which seem to emanate “features” that float away to the “lobes.” Doesn’t it look remarkably similar to what we would see based on the animation above? There are other examples in which some feature points or knots seem to move away from the core where they first appear at. We could come up with a clever model based on superluminality and how it would create illusionary symmetric objects in the heavens. We could, but nobody would believe us — because of Einstein. I know this — I tried to get my old physicist friends to consider this model. The response is always some variant of this, “Interesting, but it cannot work. It violates Lorentz invariance, doesn’t it?” LV being physics talk for Einstein’s insistence that nothing should go faster than light. Now that neutrinos can violate LV, why not me?

Of course, if it was only a qualitative agreement between symmetric shapes and superluminal celestial objects, my physics friends are right in ignoring me. There is much more. The lobes in Cygnus A, for instance, emit radiation in the radio frequency range. In fact, the sky as seen from a radio telescope looks materially different from what we see from an optical telescope. I could show that the spectral evolution of the radiation from this superluminal object fitted nicely with AGNs and another class of astrophysical phenomena, hitherto considered unrelated, called gamma ray bursts. In fact, I managed to publish this model a while ago under the title, “Are Radio Sources and Gamma Ray Bursts Luminal Booms?“.

You see, I need superluminality. Einstein being wrong is a pre-requisite of my being right. So it is the most respected scientist ever vs. yours faithfully, a blogger of the unreal kind. You do the math. 🙂

Such long odds, however, have never discouraged me, and I always rush in where the wiser angels fear to tread. So let me point out a couple of inconsistencies in SR. The derivation of the theory starts off by pointing out the effects of light travel time in time measurements. And later on in the theory, the distortions due to light travel time effects become part of the properties of space and time. (In fact, light travel time effects will make it impossible to have a superluminal dot on a ceiling, as in my animation above — not even a virtual one, where you take a laser pointer and turn it fast enough that the laser dot on the ceiling would move faster than light. It won’t.) But, as the theory is understood and practiced now, the light travel time effects are to be applied on top of the space and time distortions (which were due to the light travel time effects to begin with)! Physicists turn a blind eye to this glaring inconstancy because SR “works” — as I made very clear in my previous post in this series.

Another philosophical problem with the theory is that it is not testable. I know, I alluded to a large body of proof in its favor, but fundamentally, the special theory of relativity makes predictions about a uniformly moving frame of reference in the absence of gravity. There is no such thing. Even if there was, in order to verify the predictions (that a moving clock runs slower as in the twin paradox, for instance), you have to have acceleration somewhere in the verification process. Two clocks will have to come back to the same point to compare time. The moment you do that, at least one of the clocks has accelerated, and the proponents of the theory would say, “Ah, there is no problem here, the symmetry between the clocks is broken because of the acceleration.” People have argued back and forth about such thought experiments for an entire century, so I don’t want to get into it. I just want to point out that theory by itself is untestable, which should also mean that it is unprovable. Now that there is direct experimental evidence against the theory, may be people will take a closer look at these inconsistencies and decide that it is time to say bye-bye to Einstein.

Why not Discard Special Relativity?

Nothing would satisfy my anarchical mind more than to see the Special Theory of Relativity (SR) come tumbling down. In fact, I believe that there are compelling reasons to consider SR inaccurate, if not actually wrong, although the physics community would have none of that. I will list my misgivings vis-a-vis SR and present my case against it as the last post in this series, but in this one, I would like to explore why it is so difficult to toss SR out the window.

The special theory of relativity is an extremely well-tested theory. Despite my personal reservations about it, the body of proof for the validity of SR is really enormous and the theory has stood the test of time — at least so far. But it is the integration of SR into the rest of modern physics that makes it all but impossible to write it off as a failed theory. In experimental high energy physics, for instance, we compute the rest mass of a particle as its identifying statistical signature. The way it works is this: in order to discover a heavy particle, you first detect its daughter particles (decay products, that is), measure their energies and momenta, add them up (as “4-vectors”), and compute the invariant mass of the system as the modulus of the aggregate energy-momentum vector. In accordance with SR, the invariant mass is the rest mass of the parent particle. You do this for many thousands of times and make a distribution (a “histogram”) and detect any statistically significant excess at any mass. Such an excess is the signature of the parent particle at that mass.

Almost every one of the particles in the particle data book that we know and love is detected using some variant of this method. So the whole Standard Model of particle physics is built on SR. In fact, almost all of modern physics (physics of the 20th century) is built on it. On the theory side, in the thirties, Dirac derived a framework to describe electrons. It combined SR and quantum mechanics in an elegant framework and predicted the existence of positrons, which bore out later on. Although considered incomplete because of its lack of sound physical backdrop, this “second quantization” and its subsequent experimental verification can be rightly seen as evidence for the rightness of SR.

Feynman took it further and completed the quantum electrodynamics (QED), which has been the most rigorously tested theory ever. To digress a bit, Feynman was once being shown around at CERN, and the guide (probably a prominent physicist himself) was explaining the experiments, their objectives etc. Then the guide suddenly remembered who he was talking to; after all, most of the CERN experiments were based on Feynman’s QED. Embarrassed, he said, “Of course, Dr. Feynman, you know all this. These are all to verify your predictions.” Feynman quipped, “Why, you don’t trust me?!” To get back to my point and reiterate it, the whole edifice of the standard model of particle physics is built on top of SR. Its success alone is enough to make it impossible for modern physics to discard SR.

So, if you take away SR, you don’t have the Standard Model and QED, and you don’t know how accelerator experiments and nuclear bombs work. The fact that they do is proof enough for the validity of SR, because the alternative (that we managed to build all these things without really knowing how they work) is just too weird. It’s not just the exotic (nuclear weaponry and CERN experiments), but the mundane that should convince us. Fluorescent lighting, laser pointers, LED, computers, mobile phones, GPS navigators, iPads — in short, all of modern technology is, in some way, a confirmation of SR.

So the OPERA result on observed superluminalily has to be wrong. But I would like it to be right. And I will explain why in my next post. Why everything we accept as a verification of SR could be a case of mass delusion — almost literally. Stay tuned!

Sex and Physics — According to Feynman

Physics goes through an age of complacency once in a while. Complacency originates from a sense of completeness, a feeling that we have discovered everything there is to know, the path is clear and the methods well-understood.

Historically, these bouts of complacency are followed by rapid developments that revolutionize the way physics is done, showing us how wrong we have been. This humbling lesson of history is probably what prompted Feynman to say:

Such an age of complacency existed at the turn of the 19th century. Famous personas like Kelvin remarked that all that was left to do was to make more precise measurements. Michelson, who played a crucial role in the revolution to follow, was advised not to enter a “dead” field like physics.

Who would have thought that in less than a decade into the 20th century, we would complete change the way we think of space and time? Who in their right mind would say now that we will again change our notions of space and time? I do. Then again, nobody has ever accused me of a right mind!

Another revolution took place during the course of the last century — Quantum Mechanics, which did away with our notion of determinism and dealt a serious blow to the system-observer paradigm of physics. Similar revolutions will happen again. Let’s not hold on to our concepts as immutable; they are not. Let’s not think of our old masters as infallible, for they are not. As Feynman himself would point out, physics alone holds more examples of the fallibility of its old masters. And I feel that a complete revolution in thought is overdue now.

You might be wondering what all this has to do with sex. Well, I just thought sex would sell better. I was right, wasn’t I? I mean, you are still here!

Feynman also said,

Photo by “Caveman Chuck” Coker cc