Best yet test of Lorentz invariance

Oct 25, 2010

The more crucial a physical law is, the more important it is to keep testing it. One of the most important laws formulated in the last century or so is Albert Einsteinэs principle of invariance, which says that there is no preferred reference system or orientation in the universe.

A hypothetical violation of this principle might come about through the intervention of some not-yet-known force field.

The field would manifest itself by the simultaneous violation of three basic symmetries in nature, called CPT: charge conjugation (a symmetry which says that nature treats matter and antimatter alike), parity inversion (which says that nature can’t differentiate between left and right), and time inversion (a symmetry which holds that movies of microscopic interactions should look alike even if you reverse the order running from front to back).

In other words, looking for violation of Lorentz invariance is equivalent to looking for violations of CPT invariance.

Michael Romalis and his colleagues at Princeton look for the faint magnetic influence the hypothetical field would have on matter by watching two species of atoms – potassium and helium-3 – which are contained in a rotating vessel.

The whole lab is of course attached to the Earth, which itself rotates daily and orbits the Sun. All of these motions, carefully accounted for, should leave behind a trace of a difference for the two atomic species if an extra field exists.

The result of the latest round of observations improves by a factor of 30 the constraint on the existence of the hypothetical Lorentz-violating field.

"This is a rather dramatic improvement in CPT and Lorentz tests," says Romalis. "Our new technique also has the potential for much larger improvements in the future, so there are more limits to come."

Michael Romalis will present the findings at Frontiers in Optics (FiO) 2010/Laser Science XXVI -- the 94th annual meeting of the Optical Society (OSA). The presentation, "New Limit on Lorentz and CPT Violation for Neutrons," will take place on Thursday, Oct. 28.

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Question
1 / 5 (1) Oct 25, 2010
Doesn't the direction in which we launch satellites
indicate a preferred frame of reference? We also launch satellites using the using the earth's rotation around the sun to our advantage. Certainly we would use the rotation of our galaxy to our advantage if we sent a spaceship to other stars in our galaxy or to other galaxies. Is there any place in our universe where we couldn't use our proper motion to our advantage?
Grizzled
3.8 / 5 (4) Oct 25, 2010
No. What they want to establish is whether or not there is an abolute system of coordinates. That is, can you say that taking into account the movement of earth, Sun, Galaxy etc you can come up with some "true" velocity your piece of equipment is moving through space. Or even simpler - which direction is truly "up"?
Question
1 / 5 (1) Oct 25, 2010
The direction I can understand but the true "speed" I cannot. I must be over looking something but two other factors indicate that there is a preferred frame of reference, the Sagnac Effect and the apparent velocity we are moving in the Comic Background Radiation.
epsi00
1 / 5 (4) Oct 25, 2010
"which direction is truly "up""
well you fill a glass with water then you turn it upside down. it will certainly tell you which way is up and which is down. water does not flow "up". No?
Quantum_Conundrum
1 / 5 (1) Oct 25, 2010
"which direction is truly "up""
well you fill a glass with water then you turn it upside down. it will certainly tell you which way is up and which is down. water does not flow "up". No?


Perhaps he should have made a better choice of words.

Which direction is the "top" of the galaxy?

Which direction is the "top" of the universe?

However, "up" is also relative, because the direction that is "up" on one side of the earth is actually "down" on the opposite side of the earth. It is only if you define "up" with respect to a polar coordinate centered on the earth's CoG that you obtain consistency, in which case, "up" is simply any vector pointing away from the center of the earth.

Oh yeah, to my knowledge, no version of relativity correctly describes an observer on the surface of a planet or other object, because no version of relativity even considers the problem of the spinning observer. They deal only with uniform linear motion or linear acceleration.
Grizzled
1 / 5 (1) Oct 26, 2010
apparent velocity we are moving in the Comic Background Radiation.


I presume you meant Cosmic radiation :-)

But no, that only means that we move in relation to that radiation. It still doesn't make that reference frame somehow better than others. In particular, all physical phenomena should have the same outcome regardless in which system you look at them.

Consider the example in another question - about the water pouring out of a glass. The end result (glass is empty) remains the same even if you stand on your head (so that subjectively it flows towards your head so would appear to go "up" in your coordinate system).
CTD1
1.1 / 5 (11) Oct 26, 2010
looking for violation of Lorentz invariance is equivalent to looking for violations of CPT invariance
It would mean, LI is equivalent to CPTI, which I'm not perfectly sure about. And I'm not sure, if observation of atoms (i.e. the matter) in rotating vessel is equivalent to observation of LI (which deals with radiation).
genastropsychicallst
1 / 5 (3) Oct 26, 2010
Not-yet-known = ozon, to be read at my website.
toyo
3.4 / 5 (5) Oct 26, 2010
I can't help thinking, on reading this article, what would the Climate Warming Alarmists make of the scientists that continue to test for potential violations of such an old, established scientific principle?
What would they call them, surely "skeptics" or "deniers" would be too kind, maybe "heretics" or even "lunatics"? :-))
Shootist
1 / 5 (1) Oct 26, 2010
Oh yeah, to my knowledge, no version of relativity correctly describes an observer on the surface of a planet or other object, because no version of relativity even considers the problem of the spinning observer. They deal only with uniform linear motion or linear acceleration.


Which is why, IIRC, the initial solutions found when applying Relativity to Mercury's precession were incorrect. The math failed to account for both Earth's rotation, and its movement through space.
genastropsychicallst
1 / 5 (4) Oct 26, 2010
... field is a comma ...
mg1
1 / 5 (1) Oct 27, 2010
Well the universe is strange for a start, for one thing when "normal" things explode the debris tends not to clump and then rotate in small chunks as it whistles away in all directions.

But if i were a guessing id say you could determine top and bottom if the space into which the universe is expanding into was not expanding equally. You could probably discern this easily over time by seeing from which directions the "oldest" light comes from and form a 3d "distorted" shape from that.

Youd probably have some weird shape for the universe which would change shape as more data was added over time. But eventually you have a rough shape of the universe.

Once youve smoothed a few edges, and lobbed in a general definition of top being the furthest away youd end up with a nice map and the absolute geometry system of the universe youre after.
Decimatus
3 / 5 (2) Oct 30, 2010
I can't help thinking, on reading this article, what would the Climate Warming Alarmists make of the scientists that continue to test for potential violations of such an old, established scientific principle?
What would they call them, surely "skeptics" or "deniers" would be too kind, maybe "heretics" or even "lunatics"? :-))


They call them scientists, just like every other person who uses logic, reason, and scientific method to determine how and why things work.
Ravenrant
not rated yet Nov 01, 2010
If there is no frame of reference in the universe what is the earth dragging around that caused the mikelson morly effect? Which also seems to me that it would affect any experiment like this.
geordie_macdonald
not rated yet Nov 03, 2010
If we assigned a clock to every possible frame of reference, and could measure every clock then would the frame of reference with the fastest running clock (as per time dilation) be sitting at the origin of the universe?

Is this essentially what they are looking for?
CSharpner
5 / 5 (1) Nov 04, 2010
If there is no frame of reference in the universe what is the earth dragging around that caused the mikelson morly effect? Which also seems to me that it would affect any experiment like this

The Michaelson-Morley experiments have been repeated ad-nauseum with accuracies reaching 2 X 10^-13 with no effect detected. The aether-dragging solution proposed by Stokes was proven to be contradictory. To date, all experiments that attempt to detect our speed through the "aether" have failed. Special Relativity explains that all distances, speeds, and time references are relative and that the universe has no "preferred" frame of reference.
CSharpner
5 / 5 (1) Nov 04, 2010
If we assigned a clock to every possible frame of reference, and could measure every clock then would the frame of reference with the fastest running clock (as per time dilation) be sitting at the origin of the universe?

The fastest running clock is always your local, stationary clock (ignoring gravity, for the moment). If you and I are passing each other, rapidly, in space, your clock is slower than mine (from my point of view) and my clock is slower than yours (from your point of view). We're both right because time is relative. Faster clocks tick slower... or stated more accurately, things that move, relative to an observer, appear to be aging slower than the observer. This is true for all observers, including those that appear to be moving from your point of view (because, from THEIR point of view, THEY'RE stationary and YOU'RE moving).

So, to answer your question, "Yes" and "No". If there's no center of the universe, then all points are the center, in a way. But no.