Physicists Do What Einstein Thought Impossible

An anonymous reader writes "Einstein worked on Brownian motion (the movement of small particles in a fluid as they collide with the fluid's molecules) in 1905, but said it would be 'impossible' to determine the speed and direction of a single particle during this dance. Now researchers have gone and done it, by suspending a dust-sized glass sphere in air (which slowed down its dance moves, since it had fewer collisions with spaced-out air molecules than it would have had with water molecules). The researchers held the sphere in place with 'laser chopsticks,' and then watched how the glass bead bounced around to determine its direction and speed (abstract)."

Re:the article will be updated soon

[Kronon]

This shows the onset from the ballistic regime into the diffusive one. They can resolve the motions of the glass bead from single collisions all the way up to a statistical ensemble of them (on which scale Brownian motion is observed). I.e. this has more to do with classical statistical mechanics than quantum mechanics.

Re:Magic words...

[dgatwood]

I drank a sonic screwdriver once. They don't taste nearly as good as you might think.

Re:Magic words...

[itlurksbeneath]

Cleans your teeth, though..

Re:Am I missng something?

[maird]

If I understood the article, what you saw at high school isn't all the motion that took place. So you couldn't use what you saw to measure the velocity of a particle. What you saw was limited by the speed of light and there are changes in direction and speed that happen between the instants you observe. That's as far as I can follow it though. I don't see, for example, why it isn't frequency that's relevant to measuring it. After all, you can sample other events occurring every 100ns at only a 20MHz frequency.

Re:Keep in mind

[SoVeryTired]

They were justified to some extent. The geocentric theory based on epicycles had predictive power too: it could be used to predict eclipses to a reasonable accuracy. The heliocentric model explained the retrograde motion of planets, but also made predictions about parallax of heavenly bodies, which was not observed (since the measurements available at the time were not sensitive enough).

Bot theories had merit, and given the information available at the time, neither was perfect. That doesn't excuse the church from supressing the ideas, but it's naive to argue along the lines of "Galileo was right and the church was wrong". Galileo just didn't play the politics right.

Re:To avoid confusion

[macshit]

Must be regional variation. Around here chow mein is mostly cabbage with onions, celery and your choice of meat cooked in. No noodles at all. Looking at the wiki article on chow mein, that particular dish looks like what is usually called chow mei-fun in the local restaurants.

Yeah, but the thing is that the word which "chow mein" is a transliteration of literally means "fried noodles." Offering a dish called "fried noodles" which doesn't contain noodles, does seem a wee bit odd.

Silly regional dialects [articlesof...cation.com]...