Monthly Archives: December 2014

That's a Big Twinkie

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My 8-year-old daughter asks: If we pour water on the sun with a bucket as big as the sun, will the sun be extinguished?

The probable answer is “no.” The Sun involves a special type of fire that is able to “burn” water, and so it will just get hotter, and six times brighter.

…

Now, will such a star burn? Yes, but not with the type of proton-proton fusion the Sun uses. A star 1.7 times the mass of the Sun will heat up and burn almost entirely by the CNO fusion cycle, after making some carbon and nitrogen to go along with all the oxygen you’ve started with.

One nit, and a followup question:

Water is 89% oxygen BY MASS. And the Sun’s overall density is 1.4 times that of water. So if you have a volume of water the VOLUME of the Sun, it will have 1/1.4 = 0.71 times the mass of the Sun, and this mass will be .71*.89 = 63% of a solar mass of oxygen and 8% of a solar mass of hydrogen. The Sun itself is 0.74 solar masses of hydrogen and 0.24 solar masses of helium.

The reason the sun is denser than water is the gravitational compression, which would also be present in a bucket of water the size of the sun. So you’d probably have even more water than this. The question is whether or not the water in such a bucket would ignite fusion all by itself. Not enough mass for CNO, it would seem. A third of the atoms are oxygen — would that impede the p-p reaction? That’s about the only question I didn’t see the author address. Very thorough — almost like a What If answer.

The Coil has to Go Through Rock Ridge

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The mystery of the magnetic train

The physics behind the magnetic train that I linked to a little while back, as well as homopolar motors (which I did a long time ago)

[A]ccording to my experiments, it is necessary to make sure that the two magnets on either end of the battery have their North poles pointing in opposite directions! Otherwise, they are either both pushing or both pulling, and the “train” doesn’t move.

That was something I had thought would be true when I saw the video.

Everything is Awesome, When You're a Part of the Measurement Team

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How To Measure Planck’s Constant Using Lego

Planck’s constant comes in because of an historical idiosyncrasy in the way power units have been defined. Since 1990, almost all electrical measurements have been calibrated using a system of units in which Planck’s constant, along with various other constants, are defined rather than measured.

By contrast, mechanical power relies on ordinary SI units, which rely on a measured value of Planck’s constant. “By comparing electrical power in conventional units to mechanical power in SI units, h can be determined,” say Chao and co.

Whoops, I Did it Again

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A paper by Maggie Simpson and Edna Krabappel was accepted by two scientific journals

Much like the incident I linked to a few weeks ago. This has a nonsense paper, fictional authors (literally) and a fictitious university.

One journal immediately accepted it, while the other took a month before accepting (perhaps as part of an effort to fake peer review), but has since published it — and now keeps sending Smolyanitsky an invoice for $459.

The fact that these journals would accept the paper is absurd, and the Simpsons connection is pretty funny. But it’s also a troubling sign of a bigger problem in science publishing.

Cold but Safe

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The gloves don’t work

Scaling laws, related to why kids may be better off with mittens, and why cold fingers on a child also tells us we won’t be attacked by giant ants.

Now, my daughter is significantly smaller than me, so overall she gets colder more quickly anyway. And, given that “Gloves that work” features on her Christmas list, an equally valid answer to her question could have been “Because you need better gloves, and I’m a bad dad.” But the physics happens too.

I See London, but not Francium

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Yesterday’s link, which spent some time discussing the discovery of Francium, reminds me of a Francium story that I’ve briefly mentioned before in a story of how we failed to trap Francium, but got the attention of someone else.

And, as I had mentioned, we (well, someone at TRIUMF) got a call from a watchdog station that tries to detect nuclear fallout, wanting to double-check on things. They knew the signature they were reading wasn’t from a bomb, but they knew something was up and guessed our target material: Thorium. When you blast that with energetic protons, you get lots of heavy isotopes.

I ran across a paperfrom some folks at the monitoring facility

The United States and Canada have jointly established an experimental radio-aerosol monitoring station in Vancouver, British Columbia as part of the International Monitoring System for the Comprehensive Nuclear Test Ban Treaty. The purpose of this station is to monitor the atmosphere for the presence of anthropogenic radio-aerosols that could be indicative of nuclear explosion debris. The station has been engineered to achieve detection sensitivities that are approximately three orders of magnitude higher than conventional environmental and emergency preparedness monitors. Due to its ultra-sensitive measurement capability, the station has regularly detected micro quantities of radioisotope emissions from a nearby commercial production facility that would otherwise have gone unnoticed. The major isotope, 123I, was identified by spectroscopic analysis and correlated to the facility through source emission data.

TRIUMF would probably not be considered a commercial production facility. Although it’s possible they were making this radioisotope in conjunction with a commercial partner, I’m guessing that it was a medical radioisotope production facility. Same kind of sleuthing for the monitoring station, but a different culprit.

The Price of Discovery

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My Great-Great-Aunt Discovered Francium. And It Killed Her.

Interesting story, and an astute observation:

There is a common narrative in science of the tragic genius who suffers for a great reward, and the tale of Curie, who died from exposure to radiation as a result of her pioneering work, is one of the most famous. There is a sense of grandeur in the idea that paying heavily is a means of advancing knowledge. But in truth, you can’t control what it is that you find — whether you’ve sacrificed your health for it, or simply years of your time.

Hard work and intelligence is no guarantee of success, and some success is just pure luck. There are a number of scientists out there who will never win a Nobel, and it has nothing to do with their talent.