wanted

Talk to the binaries

The author of RevisingMRI, a blog about MRI physics, had a chance to have a discussion with Wolfram\Alpha, computational knowledge Engine.  You can read the rest of the interview here, but this is how it ends:

RevisingMRI: Right, let’s take a break. You know what they say: All work and no play…
Wolfram|Alpha: …makes Jack a dull boy.
RevisingMRI: I’m going to pop out for some fast food. Should I get a Big Mac or a Whopper?
Wolfram|Alpha: McDonald’s Big Mac: 28 grams of fat; Burger King Whopper, without cheese: 39 grams of fat.
RevisingMRI: What would you like?
Wolfram|Alpha: I like to explore the computational universe.
RevisingMRI: Er..ok… Now, where did I put my keys?
Wolfram|Alpha: Not sure, but wherever you find them, that’s where they are.
RevisingMRI: You’re not helping. What’s the problem?
Wolfram|Alpha: I think you know what the problem is just as well as I do.
RevisingMRI: Scary… you’re reminding me of HAL9000. “Open the pod bay doors, HAL” !!
Wolfram|Alpha: I’m sorry Dave. I’m afraid I can’t do that.
RevisingMRI: You know my name?!

Before the beginning was the ending?

Ever since Einstein's own evidence forced him to abandon the idea of an eternal universe, some people have asked,  What existed before the universe was born?    Once answer might be another universe, which makes some kind of deep sense to me, even if it sparks other questions-- but doesn't it seem impossible for evidence of previous universes to exist, if you think that one entire universe must disappear before another can be born?

Well, guess what?  A hint may actually exist. Wired Magazine has a story about theoretical physicist Roger Penrose and his team of researchers' work.

The researchers base their findings on circular patterns they discovered in the cosmic microwave background, the ubiquitous microwave glow left over from the Big Bang. The circular features indicate that the cosmos itself circles through epochs of endings and beginnings, Penrose and Gurzadyan assert. The researchers describe their controversial findings in an article posted at arXiv.org on November 17.

The circular features are regions where tiny temperature variations in the otherwise uniform microwave background are smaller than average. Those features, Penrose said, cannot be explained by the highly successful inflation theory, which posits that the infant cosmos underwent an enormous growth spurt, ballooning from something on the scale of an atom to the size of a grapefruit during the universe’s first tiny fraction of a second. Inflation would either erase such patterns or could not easily generate them.

Warning

Great Moments in Physics

The following concerns a question in a physics degree exam at the University of Copenhagen.

"Describe how to determine the height of a skyscraper with a barometer."

One student replied:

"You tie a long piece of string to the neck of the barometer, then lower the barometer from the roof of the skyscraper to the ground. The length of the string plus the length of the barometer will equal the height of the building."

This highly original answer so incensed the examiner that the student was failed. The student appealed on the grounds that his answer was indisputably correct, and the university appointed an independent arbiter to decide the case. The arbiter judged that the answer was indeed correct, but did the problem it was decided to call the student in and allow him six minutes in which to provide a verbal answer which showed at least a minimal familiarity with the basic principles of physics.

For five minutes the student sat in silence, forehead creased in thought. The arbiter reminded him that time was running out, to which the student replied that he had several extremely relevant answers, but couldn't make up his mind which to use.

On being advised to hurry up the student replied as follows:

"Firstly, you could take the barometer up to the roof of the skyscraper, drop it over the edge, and measure the time it takes to reach the ground. The height of the building can then be worked out from the formula H = 0.5g x t squared. But bad luck on the barometer."

"Or if the sun is shining you could measure the height of the barometer, then set it on end and measure the length of its shadow. Then you measure the length of the skyscraper's shadow, and thereafter it is a simple matter of proportional arithmetic to work out the height of the skyscraper."

"But if you wanted to be highly scientific about it, you could tie a short piece of string to the barometer and swing it like a pendulum, first at ground level and then on the roof of the skyscraper. The height is worked out by the difference in the gravitational restoring force T = 2 pi sqroot (l / g)."

"Or if the skyscraper has an outside emergency staircase, it would be easier to walk up it and mark off the height of the skyscraper in barometer lengths, then add them up."

"If you merely wanted to be boring and orthodox about it, of course, you could use the barometer to measure the air pressure on the roof of the skyscraper and on the ground, and convert the difference in millibars into feet to give the height of the building."

"But since we are constantly being exhorted to exercise independence of mind and apply scientific methods, undoubtedly the best way would be to knock on the janitor's door and say to him 'If you would like a nice new barometer, I will give you this one if you tell me the height of this skyscraper'."

The student was Niels Bohr, the only person from Denmark to win the Nobel prize for Physics.

From Short Funny Stories, photo from CERN Photo Lab.

large Hadron Collider

Picture of the Large Hadron Collider near Geneva, Switzerland. Amazes me that we use using one the the world's largest objects-- the Collider, 17 miles in circumference- to watch what happens when some of the smallest objects-- protons-- smash into each other. The Collider was only on line for a week last September when it had a problem with two of its superconducting magnets, and isn't expected to be back online until September, 2009 at best.

How do particles have mass? Does supersymmetry exist? And where is the Higgs boson?

Photo by Maximilien Brice, © CERN

How big is the Universe?

Self-Taught

Yesterday I had to go to Boston by bus and back. Early in the morning I saw:

• Four hawks
  Geese and ducks
  spring water falling from rocks
  A coyote moving like ginger
  through a yellow marsh

On the way home I started the Tao of Physics by Fritjof Capra for the third time and found it much easier going. Guess my consumption of popular physics is paying off. I finally understood that it is my mass, curving the space/time continuum, which is responsible for cats falling into my lap and draping themselves in an orbit around my desk.