Technology @lemmy.world small44 @lemmy.world 1y ago

Scientists are hoping to redefine the second – here's why

theconversation.com Scientists are hoping to redefine the second – here's why

New research has tested the latest generation of atomic clocks.

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The most relevant paragraph:

Now, using a new way of linking the clocks with ultra-fast lasers, researchers have shown that different kinds of optical atomic clocks can be placed a few kilometres apart and still agree within 1 part in 10¹⁸. This is just as good as previous measurements with pairs of identical clocks a few hundred metres apart, but about a hundred times more precise than achieved before with different clocks or large distances.
Tl;Dr They are trying to make a better atomic clock that could provide a more precise definition of a second then we currently have.
At first I was like: The second what?
- This. Same... 😅
- That's the problem when your language doesn't have capitalization for nouns
- The second division of the hour.
Can't wait for decimal time with 100,000 seconds/day /s
- Decimal time exists, thanks to the French Revolution.
  
  There are 100 decimal seconds in a decimal minute, 100 minutes in a decimal hour, and 10 hours in a decimal day. Each second is slightly shorter than a SI second.
  
  I know and nobody uses it.
- Unfortunately, there is no easy way to decimalise time for human use. If you make it useful for humans, it doesn't sync well to a day. If you make it sync to a day, the resulting units are awkward for the human mind.
  
  Amusingly, for computers, time is decimalised! UTC is a fully metric time. It's just simpler to constantly remap to and from UTC to a user's time, than to train the user to use UTC.
  
  For computers, Unix time is in binary. But yes.
  
  However, humans can get used to longer/shorter seconds, minutes and hours. Arguing the opposite is like saying the meter would never work because it doesn't have a human body relation like feet. The problem is the sheer amount of documents, equipment and SI using the 24/60/60 system, and the indivisibility of 365.24.
- I actually quite like this idea. Or we could start using number base 12 instead of 10 everywhere else.
  
  This would outdate centuries of equipment and scientific publications in the metric system.
  
  A better idea is the International Fixed Calendar:
  
  Fuck this...
- It'll likely happen once we move to living mostly in space (if we survive that long ofc)
  
  With a full switch to metric, hopefully. We’ve lost a Mars probe to unit confusion already.
Is this like when they made the kilogram some function of the speed of light instead of the weight of a metal ball in a French museum?
- They linked the kilogram to the gravitational force.
  
  It's part of an effort to clarify how we define things. We're now trying to link our recorded units to the basic forces they are related to. So now, the kilogram is defined by the gravitational force, the meter by how fast light travels, etc etc
  
  The kilogram is defined as the mass equivalent of a photon of a specific energy via the Planck constant h thus linking the speed of light and the frequency of the hyperfine level of caesium-133. The relative uncertainty of the measured value of the gravitational constant G is 10^-5 which would lead to a definition of the kilogram that has a worse relative uncertainty than using the former definition defined via an international prototype. The Wikipedka article is more detailed than this short summary.
  
  So yes?
- I misread that as "meat ball", and now I'm kind of disappointed that we don't use meatballs as a standard unit. "I'm 6 meatball subs and 3 balls high", "The yacht is about 18 giant party subs long", etc.
  
  Unfortunately this is a bit like the imperial system where you get multiple units of measurement. There is the standard foot-long, which is twelve inches, and there is the $5 foot-long™, which is only 11 inches
- Not exactly. The kilogram was redefined in a fundamentally different way, moving from an artifact, which will change with time, to a fundamental property of nature, that as far as anyone knows, will be the same at all times. The second was already defined in such a way. Any such definition still requires some sort of measurement though to get something usable. Different ways of measuring the same type of definition can be more precise, and in this redefinition they think they've found a more precise method that works in the same fundamental manner. Both measure the oscillation rate of atoms, but the proposed element is thought to give better precision.
Hey! Wait a sec
- Could you be more specific?
Would this affect our lives on Earth?
- Most likely indirectly, like how GPS has to account for satellites not matching the passage of time on earth due to relatively.
- You can now be more accurately late for work. Or your coffee is more accurately taking a long time to come out.
- Relativistically.
- If they can predict earthquakes and eruptions more accurately, as suggested in the article, then yes for all the people who don’t die.
- I better not have to buy a new watch because of this.
Wont that fuck up the other measures that use the second as a basis?

61 comments