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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)."
You had me at "laser chopsticks".
It must have been something you assimilated. . . .
When people say "impossible" they generally mean "not possible given what I currently understand about XYZ"
Unless Einstein explicitly said "this will not be possible, ever"
I mean, heck the article demonstrates this itself:
"In 1907, Einstein likely did not foresee a time when dust-sized particles of glass could be trapped and suspended in air by dual laser beam “optical tweezers.”"
I'm sorry but: No freaking shit. In 1907 I doubt many people would have foreseen that
Ha. Einstein. What an idiot.
This Einstein fella - I keep on hearing about how he's been proven wrong or might be proven wrong or how people are picking his ideas apart. It's like he hasn't even SEEN a modern physics paper in like, the last 50 years.
Google: "All your data are belong to us."
Einstein only said it was impossible from a tecnical point of view. Given he used brownian motion as direct evidence for the atomic/molecular nature of matter I am pretty sure he appreciated that with future technology it may be possible to do this kind of experiment...
TFA doesn't refute any of Einsteins conclusions about Brownian motion. It only shows that it was something impossible to do at Einsteins time. What a cheap way to grab attention!
Since when is 'dust' a unit of size?
Since they made chopsticks out of monochromatic light.
Brownian Motion is a mathematical construct, which, among other things, is nowhere differentiable (almost surely). You can pin a BM down into sets with high probability, but no, you can't really predict it. It is merely used to *model* the movement of a particle in a fluid, it is not actually the process by which the molecules move. Indeed, "such a path represents the motion of a particle that in its wanderings back and forth travels an infinite distance in finite time. [BM] does not in its fine structure represent physical reality." (Billingsley, "Probability and Measure"). At least the science is interesting.