"ตรวจสายต่อต่างๆก่อน"

วันนี้ผมได้ข่าวว่าผลที่นักวิทยาศาสตร์จับเวลาแล้วพบว่านิวตริโนวิ่งเร็วกว่าแสงอาจเกิดจากข้อผิดพลาดที่สายต่อแบบเส้นใยนำแสงต่อกับการ์ดในคอมพิวเตอร์ไม่แน่น พอไขให้แน่นแล้วพบว่าเวลาที่บอกว่านิวตริโนวิ่งมาถึงก่อนแสงจะหายไป จึงน่าจะเป็นสาเหตุที่ทำให้ผลการทดลองออกมาเป็นอย่างนั้น

พอผมได้ยินข่าวนี้ปุ๊บ ผมก็คิดถึงคำแนะนำที่มีประโยชน์กับผมมากมากว่า 25 ปีแล้ว คือถ้ามีปัญหาอะไรเกี่ยวกับคอมพิวเตอร์หรืออิเลคทรอนิคส์ทั้งหลาย ให้ตรวจดูก่อนว่าสายไฟและสายสัญญาณต่างๆต่ออยู่แน่นดีไหม ผมเห็นคำแนะนำนี้เป็นครั้งแรกในบทความของ Jerry Pournelle ตอนที่เขายังเขียนบทความให้นิตยสาร Byte อยู่ ผมจำคำแนะนำนี้ได้ขึ้นใจและใช้มันเสมอๆเมื่อต้องแก้ปัญหาเกี่ยวกับเครื่องไฟฟ้าอิเลคทรอนิคส์ทั้งหลาย

หวังว่าท่านผู้อ่านจะนำเอาไปใช้นะครับ ชีวิตท่านน่าจะดีขึ้นบ้าง :-)

ชั่งน้ำหนักวัดมวลและการทดลองเกี่ยวกับน้ำ

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สร้าง Bifurcation Diagram แบบง่ายๆ

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Today I Learned About Prince Rupert's Drops

Here's the link from Wikipedia.

The drops are "...are a glass curiosity created by dripping hot molten glass into cold water. The glass cools into a tadpole-shaped droplet with a long, thin, tail. The water rapidly cools the molten glass on the outside of the drop, while the inner portion of the drop remains significantly hotter. When the glass on the inside eventually cools, it contracts inside the already-solid outer part. This contraction sets up very large compressive stresses on the exterior, while the core of the drop is in a state of tensile stress. It can be said to be a kind of tempered glass. The very high residual stress within the drop gives rise to unusual qualities, such as the ability to withstand a blow from a hammer on the bulbous end without breaking, while the drops will disintegrate explosively if the tail end is even slightly damaged."

Here's a video clip of them exploding on YouTube:

Want To Be A Good Theoretical Physicist?

Gerard 't Hooft (a winner of the 1999 Nobel Prize in physics) has written a guide on how someone can self-study to be a good theoretical physicist. I think it's a good guide, suitable for someone serious and determined:

"...It should be possible, these days, to collect all knowledge you need from the internet. Problem then is, there is so much junk on the internet. Is it possible to weed out those very rare pages that may really be of use? I know exactly what should be taught to the beginning student. The names and topics of the absolutely necessary lecture courses are easy to list, and this is what I have done below. It is my intention to search on the web where the really useful papers and books are, preferably downloadable as well. This way, the costs of becoming a theoretical physicist should not exceed much the price of a computer with internet connection, a printer, and lots of paper and pens. Unfortunately, I still have to recommend to buy text books as well, but it is harder to advise you here; perhaps in a future site. Let's first limit ourselves to the absolute minimum. The subjects listed below must be studied. Any omission will be punished: failure. Do get me right: you don't have to believe anything you read on faith - check it. Try alternative approaches, as many as you can. You will discover, time and again, that really what those guys did indeed was the smartest thing possible. Amazing. the best of the texts come with exercises. Do them. find out that you can understand everything. Try to reach the stage that you discover the numerous misprints, tiny mistakes as well as more important errors, and imagine how you would write those texts in a smarter way."

Kelvin Water Dropper

I was looking around for science demonstration that I can do for kids and found this video of Professor Walter Lewin showing an apparatus called the Kelvin water dropper.

It works by positive feedback of electrical charge separation. Once one bucket is slightly more positive than the other bucket, it will get more and more positive, building up voltage between the buckets. When the voltage is high enough, electrical charges can travel through air, making mini lightnings (sparks.)

Professor Lewin also has an interesting interview here.

หนังสือแนะนำ (อีกแล้ว): ฟิสิกส์ 6 บทสุดง่าย

เป็นหนังสือที่แปลมาจาก Six Easy Pieces ของ Richard P. Feynman นะครับ ราคา 190 บาทเท่านั้น

ใครก็ตามที่สนใจว่าธรรมชาติทำงานอย่างไรควรจะอ่านเล่มนี้ก่อนครับ ความจริงทุกคนที่เรียนวิทยาศาสตร์ควรจะอ่านก่อน ไม่งั้นจะสับสนว่าเรียนวิทยาศาสตร์ไปทำโจทย์หรือไปสอบเท่านั้นหรือ หนังสือมีหกบทที่คัดเลือกมาจากบทบรรยายของ Richard Feynman ที่สอนนักเรียนฟิสิกส์เมื่อนานมาแล้ว เนื้อหายังดีมากอยู่ครับไม่ล้าสมัย

One of the Greatest Physicists Might Have Been Autistic

Paul Adrien Maurice Dirac was the great physicist who started the unification of special relativity with quantum mechanics and predicted the existence of anti-electrons or positrons. His name is also attached to the Fermi-Dirac statistics which describes how particles behave. He's one of the gods of physics.

He's also well known (among physicists) for his precise and laconic utterance along with his exceedingly literal interpretation of others' sentences*. I just found out that there's a new biography of Dirac that claims that he was autistics. NPR has an interview of the author and there's an article about autism screening related to Dirac.

For many amusing anecdotes about the man, see this page.

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* For example (taken from the last link above), here is typical Dirac interaction:

When Paul Dirac made a rare error in an equation on the blackboard during a lecture one day, a couragous student raised his hand: "Professor Dirac," he declared, "I do not understand equation 2."

When Dirac continued writing, the student, assuming that he had not been heard, raised his hand again and repeated his remark. Again Dirac merely continued writing...

"Professor Dirac," another student finally interjected, "that man is asking a question." "Oh?" Dirac replied. "I thought he was making a statement."

Super Science Dad Proved General Relativity To His Kids

I was amazed at Project GREAT, in which Tom Van Baak took his three children and three atomic clocks about 1.6 kilometers up Mt Rainier, stayed up there for two days, and showed that the clocks gained about 20 nanoseconds because of the high-altitude's weaker gravity.

When I told people that each person's time flows faster or slower depending on how fast that person moves or where that person is in a gravitational field, most people were incredulous. This effect is real and important enough that GPS satellites must take into account the different time flow rates for people on Earth and for the clocks on the satellites so that positions given by GPS receivers are accurate.

Some Info About Time Travel

At least two of the big movies coming out in 2009 involve time-travel, so it's a good time to review what we know and don't know about the possibility of the real time-travel to the past. Two informative and easy to understand links are Time Travel and Modern Physics and Rules for Time Travelers.

By the way, we are all traveling through time in the forward direction, so the only unknown time travel is time traveling to the past.

I think the movies Time Crimes (Los cronocrímenes) and Primer are probably closest to the real time travel if it is indeed possible.

What We Know About Giant Monsters

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Physics For Future Presidents

If you hate physics, chances are, your physics teachers sucked and didn't show you the connection between physical laws and how nature works.  If you still want to give physics a second chance, I highly recommend this website.  (If you already like physics/science in general, I think you will also find the site very entertaining.)

You can read some sample chapters and listen to the podcast.

If you don't know where to start, I suggest this page about "Waves, including UFOs, earthquakes, and music"--you get to learn about Area-51, rescuing pilots in World War II, detecting nuclear explosions, and locating earthquake epicenters. 

You can also buy the popular version of the book (as opposed to the textbook) and have a good overview of basic physics that every responsible citizens should know.  If you are in Thailand, you can find it at Kinokuniya.  I picked mine up at Kinokuniya at Siam Paragon.  I think it's still 20% off.

I learned many things I haven't realized before.  Things like the fact that chocolate chip cookies has 8 times the energy per gram compared to TNT!

Great Talk: What Is Our Place In The Cosmos?

By David Deutsch, the physicist:

You can download the talk and see additional info by going to this link.

The Physics Behind Four Amazing Demonstrations

David Willey explains why walking on broken glass, dipping fingers in molten lead, lying on a bed of nails with a concrete block broken on your chest, and picking up an orange-hot space tile are not as dangerous as they appear.

He also walked on fire.

So, the next time you see something extraordinary, before attributing it to supernatural forces or superhuman abilities, think of physics or tricks first.  If you rule out all natural explanations, you can apply to win US$1,000,000 at the One Million Dollar Paranormal Challenge.

P.S.  Mr. Willey also has a list of interesting demonstration of the laws of nature at his "How Does A Think Like That Work" page.

Another Great Physicist Passed Away

John Archibald Wheeler passed away today.

He was a living legend, had many fantastical ideas, taught and inspired generations of physicists including Richard Feynman and Kip Thorne.

I only knew him from his General Relativity book and his lectures about It-from-Bit.

 

For an example of the kind of things he imagined, check this passage from his wikipedia page:  ...theorizes experiments utilizing photons from distant locations in the universe, imaged using galaxy clusters as lenses, but which are detected using apparatus for quantum entanglement, thereby influencing history billions of years in the past.

There is also a heartfelt essay by one of his former students here.

A Genius' Quotes

Richard Feynman is my scientific hero. I decided to get real science education after reading the first few chapters from these books by him. I found these quotes when I'm ordering another of his books:
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Perhaps the best example of Feynman's self-understanding lies in his attitude toward money. After some happy years at Cornell, Feynman is lured to Caltech, where he is even happier. But one day the University of Chicago offers him "a tremendous amount of money, three or four times what I was making." He writes back:

"After reading the salary, I've decided that I must refuse. The reasons I have to refuse a salary like that is I would be able to do what I've always wanted to do -- get a wonderful mistress, put her up in an apartment, buy her nice things. . . . With the salary you have offered, I could actually do that, and I know what would happen to me. I'd worry about her, what she's doing; I'd get into arguments when I come home, and so on. All this bother would make me uncomfortable and unhappy. I wouldn't be able to do physics well, and it would be a big mess. What I've always wanted to do would be bad for me, so I've decided that I can't accept your offer."

More choice quotes:

"I learned from her [his mother] that the highest forms of understanding we can achieve are laughter and human compassion."

"That's the way the world was: You worked long hours and got nothing for it, every day."

"Have no respect whatsoever for authority; forget who said it and instead look at what he starts with, where he ends up, and ask yourself, 'Is it reasonable?' "

"Our responsibility is to do what we can, learn what we can, improve the solutions, and pass them on. It is our responsibility to leave the people of the future a free hand. . . . If we suppress all discussion, all criticism, proclaiming 'This is the answer, my friends; man is saved!' we will doom humanity for a long time to the chains of authority, confined to the limits of our present imagination. It has been done so many times before."

We Have A Testable Candidate For The Theory Of Everything!

For the past few hundred years, many scientists have tried to understand the relationship among the fundamental forces (gravity, electromagnetism, weak nuclear force, and strong nuclear force) and the various particles (electrons, quarks, etc.) that make up the matter in the Universe. The hope is to understand all these various things as aspects of one single unified idea. This is called searching for unification or searching for ToE (Theory of Everything.)

For the past twenty years, the mainstream idea about unification is the String Theory/M-Theory. I think the extremely large number (1 followed by around 500 zeroes) of possible versions of String Theory is a fatal flaw (since it's likely impossible to find experiments that rule out all versions) and blogged about a book that points this out.

Imagine my pleasure in seeing that there's an alternative candidate that can be either verified or refuted. I saw a headline called "Surfer dude stuns physicists with theory of everything" and my first reaction was he is probably another crank. Anyway, quite a few good physicists think the paper is not a joke, so I went to download it here (An Exceptionally Simple Theory of Everything).

My higher theoretical physics is extremely rusty but the paper sounds plausible. Most importantly, we will be able to check whether it's right or wrong in the next few years when suitable experiments are performed. From the paper:

The theory proposed in this paper represents a comprehensive unification program, describing all fields of the standard model and gravity as parts of a uniquely beautiful mathematical structure. The principal bundle connection and its curvature describe how the E8 manifold twists and turns over spacetime, reproducing all known fields and dynamics through pure geometry. Some aspects of this theory are not yet completely understood, anduntil they are it should be treated with appropriate skepticism. However, the current match to the standard model and gravity is very good. Future work will either strengthen the correlation to known physics and produce successful predictions for the LHC, or the theory will encounter a fatal contradiction with nature. The lack of extraneous structures and freeparameters ensures testable predictions, so it will either succeed or fail spectacularly. If E8 theory is fully successful as a theory of everything, our universe is an exceptionally beautiful shape.

Hey, maybe I will see warpdrives before I die after all!

Traveller's Guides To The Universe

I found a few links that might be handy when we all can explore space:

1. The Atlas of the Universe. Don't forget to look at the whole map.
2. What we can expect to see outside the window when we travel very fast: What would a relativistic interstellar traveller see?
3. Also, can we see the Lorentz-Fitzgeral contraction when we travel very fast?

To have some ideas about how big the universe is, think about this: In one second, light can travel the distance equivalent to about 7 times the Earth circumference. It takes light about 8 minutes to travel fromt the Sun to Earth. It takes light about 4 years to reach the nearest star outside the solar system. And it takes more than 10,000,000,000 years for light emitted by the farthest objects we can observe to reach Earth.

So, my plan is to live long enough to upload my brain state to cyborgs, wait till we have a warp drive, and explore the universe! :-D

Or maybe I will stay on Earth and watch Discovery Channel.

Understand Classical Mechanics Precisely, Very Precisely

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"Not Even Wrong" And How My Mathematical Mediocrity Accidentally Saved Me A Lot Of Grief

Not Even Wrong* by Peter Woit is a book about how string theory monopolizes the attention and resources of theoretical particle physics for the past 20 years while producing no testable prediction to decide whether the idea is correct or not. I have just finished reading the book this week, and found it to be a very interesting book. Aspiring physic students should definitely read it before they choose their research fields**.

To understand the overview of the history of particle physics in the first half of the book, the reader should be a layman interested in physics or has at least an undergraduate science training. However, any rational, scientifically-minded person can follow the conclusion of the book. The most striking passage of the book that I found is:

"Now matter how things turn out, the story of superstring theory is an episode with no real parallel in the history of modern physical science. More than twenty years of intensive research by thousands of the best scientists in the world producing tens of thousands of scientific papers has not led to a single testable experimental prediction of the theory. This unprecedented situation leads one to ask whether one can really described superstring theory research as scientific research in the field of physics. This question tends to take on two different forms. One form of the question that many physicists ask is whether superstring theory should not perhaps be described as mathematics rather than physics. A second form of the question asks whether the theory is a science at all."

In 1990, I was a junior physics undergrad at Caltech and was contemplating whether I should go into theoretical particle physics or not. At the time, string theory seemed to be the only game in town for particle theorists who want to have any chance of a tenure professorship. After a lot of investigation, I just could not see the internal beauty of the theory as claimed by many, many smarter people advocating the theory. To me, with my mediocre mathematical skills, it just seemed very complex and difficult, with no accessible physical interpretation. I decided to go into biomedical physics and software instead and followed the theoretical ideas from the sideline.

That decision turned out to be good for me in the long run. I had enough time to explore a wider range of human knowledge such as computer science, evolution, history, signal processing, statistical inference, handgunning, and Buddha's discovery. I didn't have a chance to discover the ultimate building blocks of the universe, but given that thousands of smarter people working for two decades and failing to have any testable prediction, I doubt that I would have done any better.

Well, the morals of the story are:

1. Even if you don't have great skills, you can be quite happy doing what you find personally interesting;
2. A scientific theory must make predictions that can be tested by experiments or observations. If it cannot do so, we cannot know whether it's correct or not;
3. There are infinitely many internally consistent mathematical objects. To know which one corresponds to our physical reality, we should humbly ask Nature through suitable experiments;
4. Monoculture, for living things and for ideas, is harmful. For monocultured living things, a single strand of virus can wipe out the entire population. For monocultured ideas, a fashionable but misguided idea can do a lot of damages, even to geniuses among us.

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*The famous physicist Wolfgang Pauli (of Pauli Exclusion Principle) usually proclaimed "wrong" (falsch) or "utterly wrong" (ganz falsch) when he disagreed with a scientific idea. He reserved "That is not even wrong" (Das ist nicht einmal falsch) for vague ideas that could not be confirmed or refuted, and therefore did not belong in science.

**My first blog post was about options that a highschool/college student might want to know about.