Why a Group of Physicists Watched a Clock Tick For 14 Years Straight (wired.com) 106
An anonymous reader writes: If you drop your phone today and it falls to the ground, you can be fairly certain that if it slips from your grip again tomorrow (butterfingers!), it won't suddenly soar into the sky. That's thanks to one of the basic ideas in Einstein's theory of general relativity, which posits that the laws of physics don't change over space and time. But to actually know that for a fact, you'd have to perform the same task over and over again, in as many locations as possible, and watch closely for any change in outcome. That's why, as Sophia Chen reports, a group of physicists has spent the past 14 years -- or 450 million seconds -- watching clocks tick.
Their results would have made Einstein heave a sigh of relief. The physicists were observing the 12 atomic clocks to see whether their subatomic particles' behavior changed over those 14 years -- but it was completely consistent, even as the clocks moved with the Earth around the sun. Now, these findings don't necessarily mean that the laws of physics are absolutely not changing across time and space. They only definitively show that the laws of physics stayed constant over the 14 years of the experiment. "Still, they can now say this with five times more certainty than they could a decade ago," Chen writes. "And if it holds true for Earth's location in the universe, it's not too much of a leap to imagine it's true elsewhere."
Their results would have made Einstein heave a sigh of relief. The physicists were observing the 12 atomic clocks to see whether their subatomic particles' behavior changed over those 14 years -- but it was completely consistent, even as the clocks moved with the Earth around the sun. Now, these findings don't necessarily mean that the laws of physics are absolutely not changing across time and space. They only definitively show that the laws of physics stayed constant over the 14 years of the experiment. "Still, they can now say this with five times more certainty than they could a decade ago," Chen writes. "And if it holds true for Earth's location in the universe, it's not too much of a leap to imagine it's true elsewhere."
Waiting for Godot (Score:5, Funny)
Re:Waiting for Godot (Score:5, Interesting)
Richard Feynman famously dropped his pencil as part of his quantum mechanics lectures.
Would look up, explain: There is a chance the pencil will fall up. When it did, he didn't want to miss it.
Physics Does get weird with time. (Score:5, Interesting)
Consider that the rate that time elapses here is different that in orbit, due to the distortion from Earth's gravity.
It can be measured in tall buildings, if you use a good enough clock. :)
If you're in a different gravitational field than Earth, time is passing at a different rate; the larger the gravity field, the slower time progresses, coming to a stop at the event horizon of a black hole.
(That's the Singularity thing; all the equations go bonkers at that point.)
During a drunken Physics conversation, I once postulated a situation where very near the Speed of Light, a person in a spacecraft would have problems moving his chest wall enough to breathe, because of the immense energy it would take to increase the speed of his chest; you could move away from the direction of travel easier, (slowing rather than increasing speed) so you would end up pressed to the rear wall of the spacecraft as you tried to breathe.
Everyone thought about it for a bit, and one of the guys mentioned the time dilation effect; in effect, you would never notice it, because time would be passing slow enough to hide the effect from you.
Your 'Reference Frame' would be approaching the time stoppage point.
Physics is really cool. :)
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Only for male physicists, though. (wiki [wikipedia.org] for those not in the know)
That was a piss poor excuse to stop some from staging the play....
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talk about watching paint dry (Score:2)
now, this is a job that could easily be done by an AI program.
The article summary didn't say if the physicists were actually watching the atomic clocks, or just monitoring them, but I'm hoping they were able to do some other work during the years...
Re:talk about watching paint dry (Score:5, Insightful)
A quote from TFA:
"Most of it is automated, but someone watches it all the time, and someone carries a beeper."
They are not watching the clock tick. but they are making sure the conditions stay consistent, and all parts are working.
A physical person watching a clock to see it going off by a nanosecond isn't possible.
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Doesn't it start flashing '01:00' during the spring?
Re:How would they know? (Score:4, Funny)
This doesn't account for four-cornered cubic time.
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So if we did not have memory radioactive atoms would not decay?
If we didn't have memory planets would not change position in orbit over time?
Re:How would they know? (Score:5, Insightful)
Any change would also affect the observer and the measurement device.
Ever tried to debug a problem from timestamps in log files, where the problem turned out to be clock drift? Non-trivial for sure, but possible.
What this experiment shows is that the clocks kept the same time as one another). That's something. It doesn't really show that the laws of physics are the same everywhere, just that any gradient is quite shallow across the small area the Earth traversed during the experiment. Still, it's worthwhile to do such diligence, because the underlying assumptions are so very fundamental to scientific thought that no one questions them in other work.
Experiments that confirm what everyone assumes to be true, assumes at such a deep level that its below conscious thought, those are valuable.
Still, Feynman one talked about how we could be sure there was not another fundamental force because of a similar experiment: the attraction between two uncharged masses was measured over months with extraordinary precision, and the results were as expected. That was wrong. The experiment simply wasn't accurate enough to detect dark energy, pulling the masses apart every so slightly. And dark energy is the dominate force at work in the universe, so it's a heck of a thing to miss.
So, keep doing experiments to confirm our most basic assumptions, because we can never be sure we aren't missing something.
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Experiments that confirm what everyone assumes to be true, assumes at such a deep level that its below conscious thought, those are valuable.
The unwashed masses on the right that oppose "wasting" money on science like this really don't understand that science isn't just about discovery, it's also about validation. Without the validation part, it's not science, but faith, with a high risk of being wrong, incomplete, or useless for further discoveries. This is money exceptionally well spent.
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>The unwashed masses on the right that oppose "wasting" money on science like
Slashdot isn't exactly a bastion of conservative thought, and the vast majority of comments here are "but muh tax dolarz!"
Name calling someone who disagrees with your views doesn't help.
Perhaps you'd be better off attacking the click-bait title of TFA.
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Us conservatives aren't against science. It stupid stuff like a 500K study to determine the difference in pleasure between condom and no condom.
That seems like a very cheap and worthwhile study. If greater understanding of that issue can lead to as little as one unwanted pregnancy less, the whole study has likely been a net gain for society.
Why would you be against that?
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Sure, but if the question is "do the laws of physics change over time", well, you have to keep testing over time.
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Only to rule out the one special snowflake case in which it changes with time and distance in exactly the combination necessary such that for any object the location based variance perfectly offsets the time based variance, as otherwise the light-speed delay combined with observing objects many thousands of light years apart in distance from us would revel the change with respect to time.
Nah, the laws of physics will be the same from the dawn of time until next Tuesday. They they'll change.
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Some of the clocks were of different construction and used different time-keeping mechanisms. Some were hydrogen maser, some were cesium fountain. In 14 trips around the sun, they all kept time with one another.
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That's why people who do measure this sort of thing for a living measure unitless quantities, like fine-structure constant or mass ratios [wikipedia.org].
Having skimmed through the Nature article (I never trust popular-science paraphrases, because they're work of a bunch of people who failed their physics classes trying to translate what they couldn't possibly understand), it looks like they cast their result in terms of an upper limit on variation of fine-structure constant, which is the proper thing to do.
Sigh (Score:2)
Re:Sigh (Score:5, Informative)
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Your head (if upright) is further from the center of the Earth, so it's traveling faster than your feet. Should it not age more slowly?
Different theories (Score:2)
Your head (if upright) is further from the center of the Earth, so it's traveling faster than your feet. Should it not age more slowly?
That's what is predicted by the theory of special relativity (the first one coming from Einstein, the one that posits that the speed of light remains constant in all referentials, no mater their speed).
The above post mentions prediction comming from the theory of general relativity (the second that Einstein made, the one that looks how space time is distorted by mass)
The final delta in aging that you'll be observing (the whole couple of fractions of nanoseconds of it) will heavily depend on the effect of bo
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One should also note that GPS is one of the few things in the world we use daily th
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Yes. And, according to Relativity, it does. By an infinitesimal amount (on the order of 1E-25 - in other words, all else being equal, your feet, over the period since the beginning of the Universe, will be as much as 0.03 microseconds older than your head). Note that there's a much larger (though still infinitesimal) difference between you and your parents, assuming your
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Didn't Einstein also say that ALL clocks ran at different rates based (at a minimum) on the speed they were traveling? And isn't "on the Earth" (or even "the orbit of the Earth") literally the same point in space-time compared to the size of the rest of the universe? I'm sorry, but the assumption that space-time is flat everywhere and everywhen based on this experiment is still a simplifying assumption and not some kind of bedrock fact.
As I'm guessing you know, as soon as you talk about speed, you're talking about motion - and motion is relative. Unless these scientists were observing clocks in orbit while they were on the ground, I don't think this would factor in - nor do I think it's what they were trying to test. I think it's safe to assume each clock and its respective "observer" was at rest relative to one another.
I imagine there would have been fluctuation of the acceleration both experienced, due to the shifting relative positi
It doesn't need to be proven (Score:2)
First, I'm going to preface this by saying that I'm not objecting to this experiment being carried out. I'm mostly in favor of any ethical experiment being carried out because you never know what you're going to discover. But just to raise the question...
On a certain level, I question how valuable this confirmation is. They're amount of space that they're measuring is minuscule compared to the size of the universe. The amount of time they're measuring is tiny compared to the total span of possible time
Re:It doesn't need to be proven (Score:4, Informative)
Anyway, I'd posit that the idea that "the laws of physics don't change" is more of a philosophic tautology that underlies the science of physics
This isn't true. It does underly physics, in a very important way. Because of this [wikipedia.org]
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"because you never know what you're going to discover" So, we might find that this experiment could tell us about the sex life of goats? Funny business aside, your experiment is usually prepared in such a way that your detectors will detect something you expect to find if it is there, not just anything.
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So, we might find that this experiment could tell us about the sex life of goats?
Well if it did, that would be quite a scientific discovery. Prove that ghosts exist, prove that they have sex, and tell us something about their sex lives, all with one experiment?
I mean, look, a lot of experiments turn out to be valuable not because of what they discover about the thing they're trying to measure, but because of some unexpected result that leads to some new hypothesis. There's some truth to that idea that the phrase that heralds new scientific discoveries isn't "eureka", but "that's odd.
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Tiny tiny tiny drop in the bucket, but it's a start. A good start for our current level of technology. The positive results are not show stopping. Negative results would have changed most of our understanding of the universe.
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So they have roughly a helix of 14 billion kilometers worth of data. That's... not insignificant data.
If you'd take a boat, and go out on the ocean, you wouldn't be able to detect the tides by comparing two points on the boat.
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They're amount of space that they're measuring is minuscule compared to the size of the universe. The amount of time they're measuring is tiny compared to the total span of possible time.
As others have pointed out the space isn't as small as you think, but there's something more fundamental about physics here. We don't conclusively prove much of anything by observation in physics. What we do is increase our confidence.
This experiment increased confidence significantly due to the duration of time and the movement of the earth during this time.
"Not too much of a leap" ???? (Score:3)
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The blurb you quote as saying that it's not to much of a leap to _imagine_ it's true elsewhere. I'd say it is indeed likely that it doesn't require much imagination to think that might be possible.
Being able to imagine it, and stating that it is true, are two very different statements:). I can imagine many things that are much less likely, but which I don't have enough evidence to make a truth statement about. I don't think the blurb and your view are as much in disagreement as your statement implies.
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No!!! (Score:1)
"And if it holds true for Earth's location in the universe, it's not too much of a leap to imagine it's true elsewhere."
That's just what the lab coat wearing aliens would want you to think!!!
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“Pay better attention, Zwwrkjlp! You almost forgot to wind Group 3’s atomic clock. If they’d noticed the key, that would’ve ruined everything!”
One (Score:2)
Not necessarily (Score:2)
They only definitively show that the laws of physics stayed constant over the 14 years of the experiment.
What if there were two changes which canceleld out in the measured effect?
Then the laws of physics breathed a sigh of relief (Score:2)
...and promptly made up for the lost time changing according to schedule.
You don't know a watched pot never boils?
Excuses from clock watchers (Score:2)
Tesla knew about particles. (Score:2)
He discovered X-rays before Rutherford; his images are available with a search.
Magnetism is mediated by Photons, same as every other Electro-Magnetic interaction.
Learn real physics; it's WAY more entertaining that whatever drugs you're on.
Laws of physics changed over time. (Score:2)
This is different from "Last Thursdayism Creationism" which supposes the universe was created as is 6000 years ago, with buried dinosaur skeletons and starlight already in transit for several billion light years to give the "appearance" of very old Earth.
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This is different from "Last Thursdayism Creationism" which supposes the universe was created as is 6000 years ago, with buried dinosaur skeletons and starlight already in transit for several billion light years to give the "appearance" of very old Earth.
Which is effectively indistinguishable from solipsism, at which point why does anybody bother to listen to these clowns? They're as useless as college freshman philosophers.
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But if the universe was smaller in the past (big bang theory), then wouldn't gravity have been more intense leading to different rate of time flow.
In fact, how do we know that the early inflation isn't just an artifact of a different rate of time? Since we are moving through time at a different speed now, looking back it looks like things moved apart faster in the past.
laws of physics constant? (Score:1)
Reference (Score:2)
What if it stopped? (Score:1)
Suppose the clocks stopped for 5 minutes last December. How would they know?
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Next experiment, we're going to explore whether rocks can spontaneously roll uphill if they are watched long enough.
The current quantum mechanics theories and interpretations are in favour of that possibility, but that the odds are so long that even if you watched every rock in the entire universe until all rocks have decayed, you would never see one of them move.
Smaller scale experiments, though, confirm the predictions of the theory.
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Re:Still failing to prove... (Score:5, Informative)
Science NEVER proves anything true. You are thinking of math.
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Science has made no progress _disproving_ the hypothesis that the laws of physics stay constant over vast timescales.
The only 'evidence' anybody has against that hypothesis is 'the bible' (and other traditional beliefs of illiterate shepherds). Which routinely gets laughed out of the room. But young earth creationists have two choices: Admit they're wrong, or the laws of physics _must_ change with time and distance.
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I've heard people argue "God put those dinosaur bones there to find!"
That argument is a complete waste of time; you cant reason with those people.