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Checking the Positional Invariance of Planck's Consant Using GPS

Soulskill posted more than 2 years ago | from the more-accurate-than-a-divining-rod dept.

Science 41

gzipped_tar writes "Whether the fundamental constants really stay the same is always a question worth asking. In particular, the constancy of Planck's Constant is something that cannot be simply ignored, owing to its universal importance in linking the quantum and classical pictures of our world. Using publicly available GPS data and terrestrial clocks, researchers form the California State University were able to verify that the value of h indeed stays the same across different positions in the vicinity of our Earth. Their result says the local position invariance of h is satisfied within a limit of 0.007. The paper is published in the journal Physical Review Letters (abstract), and a free-to-read preprint is available on arXiv. In short: by the well-known formula E = h * f, a hypothetical variation on h induces changes in f, the transition frequency that keeps the time in atomic clocks, both on earth and aboard the satellites. When taking account of other time variations, such as general relativistic time dilation, and assuming the invariance of E (atomic transition energy) on physical grounds, we can figure out an upper bound on the variation of h reflected in the measured variation in f."

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Obviously... (-1, Redundant)

busyqth (2566075) | more than 2 years ago | (#39383989)

Obviously it doesn't change. That's why it's called Planck's Constant!

Re:Obviously... (3, Insightful)

marcosdumay (620877) | more than 2 years ago | (#39384671)

As oposed to the well known engeneering saying that "variables won't, constants aren't"?

Sometimes constants aren't constant in physics either. If we don't look for variances, we won't ever be sure that something is constant.

Good stuff to be sure. (-1)

wbr1 (2538558) | more than 2 years ago | (#39384003)

In short: by the well-known formula E = h * f, a hypothetical variation on h induces changes in f, the transition frequency that keeps the time in atomic clocks, both on earth and aboard the satellites. When taking account of other time variations, such as general relativistic time dilation, and assuming the invariance of E (atomic transition energy) on physical grounds, we can figure out an upper bound on the variation of h reflected in the measured variation in f."

But have you figured out why your not getting laid yet?

Re:Good stuff to be sure. (0, Redundant)

Anonymous Coward | more than 2 years ago | (#39384051)

But have you figured out why your not getting laid yet?

No. But have you figured out why you're not using the correct form of you're?

Re:Good stuff to be sure. (1, Funny)

Anonymous Coward | more than 2 years ago | (#39384095)

In short: by the well-known formula E = h * f, a hypothetical variation on h induces changes in f, the transition frequency that keeps the time in atomic clocks, both on earth and aboard the satellites. When taking account of other time variations, such as general relativistic time dilation, and assuming the invariance of E (atomic transition energy) on physical grounds, we can figure out an upper bound on the variation of h reflected in the measured variation in f."

But have you figured out why your not getting laid yet?

His dick is so small Heisenberg's Uncertainty Principle is a factor. If he moves it he can't find it, and if he finds it he can't move it.

Re:Good stuff to be sure. (2)

TempestRose (1187397) | more than 2 years ago | (#39387015)

And when I want to have points, I don't. When I don't want to have points, I do. I would love points for this. Someone mod this up, anon or not, funny as hell.

Textbook publishers are disappointed (-1)

Anonymous Coward | more than 2 years ago | (#39384017)

They were dreaming of multitudes of new physics textbook editions to force-feed to students.

And the professor who discovered each possible variable of h would get a cut of the revenue...

some subject (1)

sarduwie (1571169) | more than 2 years ago | (#39384103)

this reads like time cube

Re:some subject (2)

EdIII (1114411) | more than 2 years ago | (#39384773)

Nothing reads like time cube. Nothing. :)

First off, your brain starts to bleed just from the background image. Then the evil cube gods start programming you with their evil 4 day belly button logic. Forced extraction of your educated stupidity and oneness, one god mentality is commenced.

That whole website is a complete riot. It's like stream of consciousness writing from a mental patient they have not found the correct medication for.

Re:some subject (2)

mmontour (2208) | more than 2 years ago | (#39385209)

Nothing reads like time cube. Nothing. :)
First off, your brain starts to bleed just from the background image

The funniest thing for me is that when you finally scroll down to the bottom of that wall of crazy-text, there's a "next page" link.

Re:some subject (1)

EdIII (1114411) | more than 2 years ago | (#39385521)

Nothing reads like time cube. Nothing. :)
First off, your brain starts to bleed just from the background image

The funniest thing for me is that when you finally scroll down to the bottom of that wall of crazy-text, there's a "next page" link.

Have you clicked it? :) That's where the real journey begins. If you think the first page was batshit crazy....

Re:some subject (1)

Kreigaffe (765218) | more than 2 years ago | (#39385303)

I don't know if it's LIKE that..
I think it may BE that.

Re:some subject (1)

khallow (566160) | more than 2 years ago | (#39386859)

It's like stream of consciousness writing from a mental patient they have not found the correct medication for.

Probably because the medication doesn't exist yet.

Four time zones (4, Funny)

tepples (727027) | more than 2 years ago | (#39385105)

Time Cube starts to make a bit more sense when you realize that "four simultaneous 24-hour days" is just a long way of saying "four time zones". But GameCube [fateback.com] still makes more sense.

Re:Four time zones (1)

nitehawk214 (222219) | more than 2 years ago | (#39385275)

Time Cube starts to make a bit more sense when...

Ok, take tepples away... there is no hope for him.

Re:Four time zones (0)

Anonymous Coward | more than 2 years ago | (#39386023)

But GameCube [fateback.com] still makes more sense.

Wow, that's amazing. How have I never seen that before?

I apologize; I have no mod points at the moment.

Clocks (0)

SnarfQuest (469614) | more than 2 years ago | (#39384137)

Using publicly available GPS data and terrestrial clocks,

Are these the same clocks they used to prove that some particles could exceed the speed of light?

Re:Clocks (1)

kurzweilfreak (829276) | more than 2 years ago | (#39384299)

No, it's different clocks, but they got a deal on the connecting cables from LHC...

Lucky scientists (1)

Anonymous Coward | more than 2 years ago | (#39384139)

Scientists get to have all the fun. Most people would have to worry about being fired for Plancking while on the job.

*ba-dum tssh*

Re:Lucky scientists (1)

Sulphur (1548251) | more than 2 years ago | (#39386451)

Scientists get to have all the fun. Most people would have to worry about being fired for Plancking while on the job.

*ba-dum tssh*

Watch out for adulterated Planck.

Disappointment (0)

Anonymous Coward | more than 2 years ago | (#39384151)

I can't help but wonder if they aren't at least a little disappointed that there wasn't some small systematic error that would have indicated some variation of the Planck constant. They came up with a complex experiment, collected all the data, and then nothing changes. The FTL neutrino guys certainly got a lot more out of their mistake than these people will get out of their "yup, everything as expected" result.

one scientist's "noise" is another's "signal" (3, Insightful)

peter303 (12292) | more than 2 years ago | (#39384155)

Errors in GPS results have been unwound to tell thinks about atmospheric ionization, general relativity, and now planck's constant.

Huh? (0)

Anonymous Coward | more than 2 years ago | (#39384275)

Huh?.... There's not a lot of posts I don't understand on Slashdot but this is defiantly one off them...

Fix (3, Informative)

wirelesslayers (2014486) | more than 2 years ago | (#39384305)

Checking the Positional Invariance of Planck's Consant Using GPS
to
Checking the Positional Invariance of Planck's Constant Using GPS

Re:Fix (1)

dgatwood (11270) | more than 2 years ago | (#39384821)

To be fair, they weren't certain about that until just now.

Re:Fix (3, Funny)

fish waffle (179067) | more than 2 years ago | (#39384899)

It seems pretty clear they meant Planck's Consonant. Some argued it was "P" but they've now verified that it's an "h".

Re:Fix (1)

Sulphur (1548251) | more than 2 years ago | (#39386461)

Checking the Positional Invariance of Planck's Consant Using GPS

to

Checking the Positional Invariance of Planck's Constant Using GPS

Planck's consonant is h.

Very large limits (3, Interesting)

steamraven (2428480) | more than 2 years ago | (#39384375)

Given that h is very small (1e-15, 1e-34 or 1e-27 depending on units), a limit of .007 seems rather large.

Re:Very large limits (4, Informative)

Mac Scientist (153390) | more than 2 years ago | (#39384799)

Given that h is very small (1e-15, 1e-34 or 1e-27 depending on units), a limit of .007 seems rather large.

Considering NIST in Washington, NRC in Ottawa, NPL in London, and METAS in Berne (all national metrology labs) have directly measured h to within 300 parts in a billion (1E9), this is an unusual report. Those results are within a relative limit of 0.0000003.

Planck's constant cannot be measured with only a GPS or atomic clock, so this is at best some comparative result.

Re:Very large limits (2)

Obfuscant (592200) | more than 2 years ago | (#39385427)

Planck's constant cannot be measured with only a GPS or atomic clock, so this is at best some comparative result.

Yeah, that's kinda the point of calling it positional independence. They're reporting how constant the constant is, not what its value is.

Re:Very large limits (1)

Edzilla2000 (1261030) | more than 2 years ago | (#39385005)

Don't tell him that, he's got a licence to kill!

Re:Very large limits (1)

Shavano (2541114) | more than 2 years ago | (#39385589)

I assume that's relative, but even so it's still very large considering the relative scale of the universe and the fact that we can easily measure frequency to 1 part in 10^10.

Re:Very large limits (3, Informative)

FrootLoops (1817694) | more than 2 years ago | (#39387101)

The summary could have been clearer, but the 0.007 number isn't even remotely close to representing absolute error bounds. It's actually a scaled relative error--that is, the amount the ratio of Planck's constant at one position to the value at another position differs from 1, multiplied by a scale factor. That scale factor is somewhat complicated and depends on the speed of light as well as the gravitational field and velocity of measurement devices at each position. I don't know enough general relativity to explain the reasoning behind the particular scale factor chosen. Without that reasoning the quoted number is almost useless; perhaps someone else can provide it.

From the abstract:

The results indicate that h [Planck's constant] is invariant within a limit of |\beta_h| < 0.007, where \beta_h is a dimensionless parameter that represents the extent of LPI [local position invariance] violation.

[For those unfamiliar with TeX markup, \beta is just the Greek letter beta, and _ indicates a subscript.]

The paper defines \beta_h in equation (6):

LPI violations for h can be written as
        h_x/h_o = 1 + \beta_h \Delta U / c^2
where h_o is the locally measured value of h at reference point O, h_x is its locally measured value at x, and \beta_h is the parameter for Planck’s constant.

\Delta U had been defined just after equation (1):

The potential difference is \Delta U = U_x - U_o,
where U_i = \Phi_i - v_i^2 / 2, \Phi_i is the gravitational potential energy per unit mass and v_i is the clock’s velocity.

Good start, but let's do better (1)

Anonymous Coward | more than 2 years ago | (#39385115)

My big gripe with physics is a lot of its models assume...linearity of systems. I don't want to be the asshole who begins with "assume an invisible, silent, odorless dragon in the garage"...

Because I know that's not science.

But -- I'd like to see a little more exploration and less blind Faith in science. Which by definition is happening in the known universe. I'm not asking people to check the unknown universe, but let's measure on a bit more than... earth.

Can we get this tested under more *interesting* conditions than earth?

Can we test plank's constant as we accelerate an object near light speed or subject it to overwhelming gravitational force? How about as we heat or cool it? How about as we take that quanta and accelerate or decelerate it?

This isn't to say scientists should test all conceivable systems --but there are a variety of fundamental units and forces in the universe in which behavior has been shown to couple in unexpected manners when dealing with "sufficiently large or small" units. Planck's constant handles the small end. Let's see what it does at the other extreme.

Re:Good start, but let's do better (1)

stevelinton (4044) | more than 2 years ago | (#39387601)

Can we get this tested under more *interesting* conditions than earth?

Can we test plank's constant as we accelerate an object near light speed or subject it to overwhelming gravitational force? How about as we heat or cool it? How about as we take that quanta and accelerate or decelerate it?

Many of these are possible, in a sense, although what you actually test is not Planck's constant but various combinations of it and other constants which eventually give pure dimensionless numbers. The best known of these is alpha which measures the strength of the electromagnetic force.

Limits on values of alpha in extreme conditions (or over long periods of time) can be determined from astronomical observations -- different spectral lines would shift by different amounts if alpha, changed, for instance, so by comparing their relative positions in light from objects in extreme conditions, we learn something. So we observe light from hot gas falling into a black hole, or light from distant galaxies that has been gravitationally lensed by nearer ones, or whatever and see what the spectra look like. It's not easy, but it is possible. These reports are interestingly, about equally sensitive to change over time as measurements on Earth using ultra-stable atomic clocks, where the time periods are much shorter, but the measurements much more accurate.

We also regularly study the properties of particles and atoms moving very close to light-speed indeed in particle accelerators.

not very precise (1)

Shavano (2541114) | more than 2 years ago | (#39385547)

That result is interesting but if the variation of h across Earth's orbit court be as high as 0.007, it could on principle be much greater across much.larger scales. Is it the same at the center of the galaxy? In other galactic clusters? Over billions of years? The conditions of measurement were very small compared to those scales.

We can measure frequency with much more precision than anything else. I'm surprised their upper bound is so high.

sh1t (-1)

Anonymous Coward | more than 2 years ago | (#39386523)

Typo in summary (0)

shentino (1139071) | more than 2 years ago | (#39386889)

It's spelled constant, not consant.

TIME? (0)

Anonymous Coward | more than 2 years ago | (#39387349)

This is invariance across space. Next we need to check invariance across Time

Soooo ... (0)

Anonymous Coward | more than 2 years ago | (#39387937)

Where's the map?

Planck's constant is a conversion factor (0)

Anonymous Coward | more than 2 years ago | (#39398981)

that relates our unit of mass to the unit of time. If Planck's constant varied, it would be saying that either our standard kilogram, or atomic clocks vary in our neighbourhood - something that can be tested independently. I'm not sure what this research is actually achieving.

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