Physicists prove Einstein wrong with observation of instantaneous velocity in Brownian particles

May 20, 2010
A 5-micrometer glass bead levitated in air by a single laser beam from below. This optical trap is formed by the balance between the scattering force from the laser beam and the gravitational force on the bead. Tongcang Li, et. al. used a similar optical trap to study the Brownian motion of a trapped bead in air with ultra-high resolution. Their paper is published in Science. Credit: Tongcang Li, the University of Texas at Austin

A century after Albert Einstein said we would never be able to observe the instantaneous velocity of tiny particles as they randomly shake and shimmy, so called Brownian motion, physicist Mark Raizen and his group have done so.

"This is the first observation of the instantaneous velocity of a Brownian particle," says Raizen, the Sid W. Richardson Foundation Regents Chair and professor of physics at The University of Texas at Austin. "It's a prediction of Einstein's that has been standing untested for 100 years. He proposed a test to observe the velocity in 1907, but said that the experiment could not be done."

In 1907, Einstein likely did not foresee a time when dust-sized particles of glass could be trapped and suspended in air by dual "." Nor would he have known that ultrasonic vibrations from a plate-like transducer would shake those glass beads into the air to be tweezed and measured as they moved in suspension.

Raizen's research, published in Science, is the first direct test of the equipartition theorem for Brownian particles, one of the basic tenets of statistical mechanics. It is also a step toward cooling glass beads to a state in which they could be used as oscillators or sensors.

The equipartition theorem states that a particles' kinetic energy—the energy it possesses due to motion—is determined only by its temperature, not its size or mass.

Raizen's study now proves that the equipartition theorem is true for Brownian particles; in this case, glass beads that were three micrometers across.

Raizen says he and his colleagues can now push the limits, moving the particles closer to a for observation.

"We've now observed the instantaneous velocity of a Brownian particle," says Raizen. "In some sense, we're closing a door on this problem in physics. But we are actually opening a much larger door for future tests of the equipartition theorem at the quantum level."

There, he expects that equipartition theory will break down, leading to new problems and solutions surrounding the quantum mechanics of small particles composed of many atoms.

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User comments : 22

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JCincy
3.2 / 5 (19) May 20, 2010
Why the insult against Einstein? Consider the technology he had available when he made his statement. And then consider the advances he brought to science.
Alizee
May 20, 2010
This comment has been removed by a moderator.
axemaster
4.4 / 5 (8) May 20, 2010
"A century after Albert Einstein said we would never be able to observe the instantaneous velocity of tiny particles as they randomly shake and shimmy, so called Brownian motion, physicist Mark Raizen and his group have done so."

Well, perhaps I'm just nitpicking, but they really haven't - at least not in the way the phrasing of the article suggests. Quantum mechanics and Heisenburg's uncertainty principle limit the resolution of experiments in the following way (where UN stands for uncertainty):

(UNx)(UNp) >= Hbar/2

Of course, it's the writer of the article who is at fault here. Oh well.
Scientifica
May 20, 2010
This comment has been removed by a moderator.
Kedas
3 / 5 (2) May 20, 2010
I guess that proving theories wasn't really his thing.
He knew he was right about his theories anyway.
pba
May 20, 2010
This comment has been removed by a moderator.
gunslingor1
2 / 5 (4) May 20, 2010
He also knew he was wrong about his theories too, remember cold fussion.
Alizee
May 20, 2010
This comment has been removed by a moderator.
Caliban
2.3 / 5 (6) May 20, 2010
Perhaps Einstein intended it as a challenge- knowing full well that it would lead to probably much larger discoveries at quantum scale- where all the action is really happening.
theophys
5 / 5 (2) May 20, 2010
He also knew he was wrong about his theories too, remember cold fussion.

A better example would be Einstein's change in heart over the expanding universe.
Also, I'm pretty sure nobody was putting any significant work into cold fusion until after Einstein died. I could be wrong.
Husky
4.3 / 5 (6) May 21, 2010
even when einstein was wrong, he was right by setting up the challenge
Kimberbang
5 / 5 (1) May 21, 2010
I have always considered the physics breakthroughs of that era to have been a team effort as it were. The lot of them standing on the shoulders of giants. Of course it is easy to give the glory to the eccentric with wild hair!
magpies
May 21, 2010
This comment has been removed by a moderator.
bugmenot23
5 / 5 (3) May 21, 2010
(bugmenot account)Not a bad article, why the god-awful exaggerating headline? Physics nubs will think it is one of his actual theories, you know..
ZeroX
2.6 / 5 (5) May 21, 2010
Not a bad article, why the god-awful exaggerating headline?
Because science is tabloizied on behalf of trivial findings and experiments.
tkjtkj
not rated yet May 21, 2010
Why the insult against Einstein? Consider the technology he had available when he made his statement. And then consider the advances he brought to science.

yes, agreed! To suggest he was 'wrong' about the future is an absurd criticism .. and, consequently, non-scientific .. but then, this is physorg ..
ArtflDgr
5 / 5 (1) May 21, 2010
They made a mistake...
not in their work but in the interpretation and relationships. i will give a hint, as i dont feel like debating and who gives a rats bum any way?

here is the hint... think wavelength, and the time band each is capable of working in, and how a portion of what they are working with happens outside this band.
Alizee
May 21, 2010
This comment has been removed by a moderator.
Alizee
May 21, 2010
This comment has been removed by a moderator.
DamienS
3.7 / 5 (6) May 21, 2010
This article is atrocious (though the research is excellent). Einstein was hardly 'proved wrong'. His great insight was the realization that Brownian motion of particles in a fluid stemmed directly from the kinetic model of thermal equilibrium (how heat worked was still debated at the time). It confirmed that the second law of thermodynamics was essentially statistical in nature.

As an aside, he stated that it would likely be impossible to measure the instantaneous velocity of such particles. This is just a minor and understandable comment. In fact, it still holds true. This experiment doesn't measure BM in a liquid, but in air. That's because the velocities are lower in air. Doing so in water is still not possible.

Nothing like a sensationalist headline - 'Einstein proved wrong', or 'Darwin proved wrong"!
Alizee
May 22, 2010
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DamienS
3 / 5 (2) May 22, 2010
Yes.

"Now, Mark Raizen, Tongcang Li and colleagues at the University of Texas at Austin have found a way round this problem by studying particles in air rather than a liquid. Because air is much less dense than water its molecules are farther apart and therefore the distance, and time, between Brownian collisions is much greater. Indeed, velocity of a Brownian particle changes about once every 100 µs in air".
http://physicswor...ws/42679
frajo
5 / 5 (1) May 22, 2010
The average speed of molecules in water is lower, then in the air because of lower mean free distance.
Average velocity is not instantaneous velocity.
DamienS
2 / 5 (2) May 22, 2010
Yes.
"Now, Mark Raizen, Tongcang Li and colleagues at the University of Texas at Austin have found a way round this problem by studying particles in air rather than a liquid. Because air is much less dense than water its molecules are farther apart and therefore the distance, and time, between Brownian collisions is much greater. Indeed, velocity of a Brownian particle changes about once every 100 µs in air".

"http://physicswor...9"
labtvonline
5 / 5 (4) May 22, 2010
I love how long after his death people are still using Einstein as a bench mark. That guy was so far beyond it is not even funny.
Alizee
May 22, 2010
This comment has been removed by a moderator.
ggg
2 / 5 (4) May 25, 2010
I love how any refuting of Einstein is treated as sacrilege.
I also love how anything that refutes Einstein is accounted as wrong by presumption like the particles that seem to reach the Earth at velocities > c.
I especially love it when something that shows the Einstein was wrong is held up as showing he was right. That is the attraction to a moving magnet experiment which clearly shows that objects are attracted to where the magnet is now; not where it was.
Alizee
May 25, 2010
This comment has been removed by a moderator.
Alizee
May 25, 2010
This comment has been removed by a moderator.
frajo
3.7 / 5 (3) May 25, 2010
I love how all those students who have been disdained by physics try to take their revenge by "refuting" A.E. :)
Alizee
May 25, 2010
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Alizee
May 25, 2010
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Skultch
not rated yet May 27, 2010
In notion of dense aether model the God is dual to invisible quantum noise and "angels" are visible representation of it. Due the uncertainty principle, the motion of tiny particles is effectively superluminal, at least a bit.

Maybe just this aspect of quantum motion Einstein had on his mind, when he talked about impossibility to follow quantum noise in causal way. His interest about Brownian motion wasn't accidental at all - he knew, the space-time must remain in eternal noise for relativity be able to work.


Is this "noise" only our ignorance; our limited perspective? Are these ideas of god and angels another placeholder for our current and temporary intellectual limitations?
googleplex
5 / 5 (1) May 28, 2010
I am sure that Einstein did not imply it would be impossible for ever. Infinity is a long time!
Also remember that even quantum theory breaks down at a small enough scale.
Alizee
May 28, 2010
This comment has been removed by a moderator.
Alizee
May 28, 2010
This comment has been removed by a moderator.
xstos
Jun 01, 2010
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Skultch
not rated yet Jun 02, 2010
... in hypergeometry of extra-dimensions. The projection of harmonic motion of some large object in extra-dimensions into our 3D world leads into experience of chaotic motion of tiny points. ... We cannot pass it through Turing's test. This doesn't say, our Universe is part of intelligent program or omnipotent deity, but we cannot resolve it reliably from out limited perspective, because it doesn't cooperate with us. Therefore the idea of God remains substantiated from certain perspective in the same way, like the idea of hidden order in extradimensions.


You are all over the place here. I don't think you use hypergeometry correctly, and the Turing analogy isn't apt. I roughly get where you're going, though. Theory, based on theories, based on ignorance; philosophy for the haphazardly educated, like me. :) Still, the "large object" is still a placeholder, and is why I'm temporarily finished with this kind of philosophy. No faith in science or otherwise here. :)