Stories tagged atoms

Saw this rerun of WKRP in Cincinnati last night. This clip really puts the "informal" in informal science education. I believe this episode dates back to like 1981, but the jargon is still up-to-date.

Jan
11
2010

Radioactive Peace: With all countries taking from a nuclear fuel bank, no one country will have to enrich its own uranium.
Radioactive Peace: With all countries taking from a nuclear fuel bank, no one country will have to enrich its own uranium.Courtesy kso
Talk of nuclear power has been brought back into the spotlight, especially after the discovery of Iran’s uranium enrichment plant last September. A solution to the debate about whether countries should even have the capability of enriching uranium (the process required for attaining both nuclear energy and nuclear weapons) was posed more than 50 years ago by President Eisenhower. Eisenhower suggested that various countries should allocate uranium from their stockpiles for peaceful pursuits (i.e. nuclear energy). At the time it wasn’t received very well, but a recent BBC article reported that this vision has been renewed. As of November of last year, the United Nation’s International Atomic Energy Agency (IAEA) successfully negotiated with Russia to store 120 tonnes of nuclear fuel in a plant in Angarsk (a city in the south central-ish part of Russia). In 2010, similar arrangements are said to be made with Kazakhstan. The idea is to get developing countries that are thinking about using nuclear energy in the future to join in this program, eliminating their need to enrich their own uranium.

All of this got me thinking about how nuclear energy actually works. It turns out that nuclear power plants are not that different from regular coal-burning power plants. Both plants heat water to produce pressurized steam. This steam then drives a turbine, which spins a generator to produce electricity. The only difference between the plants is how the water is heated. Coal-burning plants…well, burn coal (fossil fuels) to produce the heat, while nuclear plants rely on nuclear fission. This is where nuclear power gets really cool!

So atoms are made up of protons, neutrons, and electrons; protons are positively charged, neutrons carry no charge, and electrons are negatively charged. Atoms have an equal number of protons and electrons (making the atom, itself, electrically neutral), but the number of neutrons can vary. Atoms of the same element with a different number of neutrons are called isotopes. The isotope of uranium that is needed for nuclear fission, and therefore, nuclear energy, is Uranium-235. This isotope is unique because it can undergo induced fission, which means its nucleus can be forced to split. This happens when a free neutron runs into the nucleus of U-235. Nuclear fission
Nuclear fissionCourtesy wondigama
U-235 absorbs the neutron, becomes unstable, and breaks into two new nuclei. In the process, two or three neutrons are also thrown out. All of this happens in a matter of picoseconds (0.000000000001 seconds)! The neutrons that are released in this reaction can then go and collide with other on-looking U-235 atoms, causing a huge chain reaction (much like this). The amount of energy released when this happens is incredible- a pound of highly enriched uranium has about the same energy as a million gallons of gasoline. This energy comes from the fact that the products of the fission (the two resulting nuclei and the neutrons that fly off), together, don’t weigh as much as the original U-235 atom. This weight difference is converted directly into energy. It’s this energy that is used to heat the water that creates the steam, which turns the turbine that spins the generator, that produces power in the nuclear reactor that Jack built.

On the plus side, with nuclear power there wouldn’t be a reliance on fossil fuels. Nuclear power plants are cleaner because they don’t emit as much carbon dioxide as traditional coal-burning and natural gas plants. However, there are some downsides as well. Mining uranium is not a clean process, transporting nuclear fuel creates a risk of radioactive contamination, and then there’s the whole issue with what to do with the still-dangerous nuclear waste once the fuel has been used up.

Whether or not we should increase our nuclear power program is still debatable, but one thing I do know is that the science behind it is fascinating!

Apr
27
2009

Remember on TV's Star Trek how Captain Kirk's impossible requests were always put off by his chief engineer, Montgomery Scott? Scotty favorite excuse for avoiding work was to claim it just wasn't physically possible. This from the guy whose engineering skills could propel a starship across the universe at Warp Factor 10 using a couple lousy dilithium crystals. Or maybe he just had better things to do. Whatever the case, it looks now like Scotty's favorite work shirk excuse may no longer be valid. At least not in the world of nanoclusters.

While exploring strange new worlds using computer modeling and nanoclusters made up of several hundred atoms, researchers in Japan have observed tiny clumps of atoms that seem to break the second law of thermodynamics. Don’t think crime is rampant in the nano-world. Most of the atoms observed were law-abiding. When the nanoclusters collided at just under 12 miles per hour, most of them either clumped together like sticky mud, or bounced off each other and went on their way at a slower speed.

But a small percentage of nanoclusters (less than 5%) bounced away at an increased speed, acting as if they picked up an extra boost of energy.

It’d be like dropping a golf ball on the sidewalk and instead of it gradually losing energy (as absorbed heat) and eventually coming to a dead stop, as expected, it just went higher and higher with each successive bounce until it finally bounced into orbit. That just doesn’t make sense. Or as Scotty’s cohort Mr. Spock would say: “Logic and practical information do not seem to apply here.”

According to the researchers, Hisao Hayakawa, of Kyoto University, and Hiroto Kuninaka, of Chuo University in Tokyo, the so-called super rebound resulted from random internal changes of motion in the nanocluster’s atoms, some of which can give the collision an extra boost, like jumping on a trampoline.

Sounds like we got ourselves the makings for some sort of perpetual motion machine here. Well, not quite. Apparently, this scofflaw behavior can only take place in very tiny systems. When the researchers increased the cluster’s atoms from hundreds to thousands, the behavior disappeared completely.

Besides that, the system as a whole still followed the letter of the law. The second law deals statistically with millions of atoms, so even though some nanoclusters picked up extra energy, the clusters overall dispersed energy and headed towards increased entropy just as the law prescribes, and in the end all is well with the universe.

So far the phenomenon has only been seen in computer simulations. But Hayakawa expects it won’t be long before it’s observed in real world experiments. The research findings appeared in the March issue of Physical Review E.

“Fascinating, Captain.”

LINKS

Science News story
More about the second law of thermodynamics

When you're building nanostructures, the position of each and every atom counts. After all, that's one of the factors that determines, for example, whether a material will be a semiconductor or an insulator, or whether it will start up a process or stop it. But our current imaging techniques aren't precise enough yet to give us full control over nanomaterials. Researchers are working to combine tools we have with new approaches to the data they yield to develop atom maps. Pretty cool.

Atom trappers: Plug your guitar into an amp and just see how many atoms you can trap to do crazy science experiments on.
Atom trappers: Plug your guitar into an amp and just see how many atoms you can trap to do crazy science experiments on.Courtesy Derek K. Miller
Do you like to rock out? Do you like to isolate atoms and bombard them with laser beams? An physicist/musician in England has figured out how to use guitar amps to conduct such experiments. Read all about it here. What I want to know is if you use a Spinal Tap amp, one of those cool jobs you can turn all the way up to "11," can you trap more atoms?

Nov
19
2007

Garrett Lisi, a 39-year-old surfer, hiking guide and construction worker (with a PhD in theoretical physics), believes he may have solved the biggest problem in all of science – how are all the particles of matter and forces of nature related to one another? Scientists since Einstein have been trying to figure it out, with little success. (The current theory involves outrageously tiny “strings” vibrating in 11-dimensional space. The mathematics, they say, is beautiful, but it cannot be tested or verified.) Lisi’s breakthrough came when he noticed that the formulas that describe something called the E8 pattern -- a complex, geometrical design with 248 points – also describe many of the fundamental forces and particles. His theory is that nature follows the same formulas as E8, and that the figure can be used to predict particles that have not yet been discovered. If he's right, he will have finally shown that everything in the universe is related, and basically just different manifestations of the same essence.

Rad, dude.

Jun
28
2007

Physicist John Cramer at the University of Washington has an idea. He believes that certain sub-atomic phenomena can best be explained if information can travel backwards in time. And his idea has created enough of a buzz on the Internet that private citizens are funding his work after normal, government funding sources turned him down.

It’s all about something called the Einstein-Podolsky-Rosen paradox. If certain sub-atomic particles are split, the two halves still react to one another instantaneously, even if they are separated by immense distances. Since the two particles are not connected in space, Cramer figures they must be connected in time. He has an idea for a small-scale experiment to see if his concept is even feasible, but none of the big agencies would bite.

But when word got out, various individuals who thought the idea was cool started sending in money. Cramer now hopes to get his first experiment up and running in July. If it works, he will then approach the big agencies again – this time, with a track record of success.