7 ms·
NIST Pair of Atomic Clocks Reveal Einstein's Relativity at a Personal Scale
- xattt 6y agoNeeds a 2010 tag.
- Intermernet 6y agoOnly in your frame of reference...
- gonzo41 6y agonice, I laughed
- ortusdux 6y agoReminds me of project GREAT: http://www.leapsecond.com/great2005/ http://www.leapsecond.com/great2005/ I wish my dad threw us in the back of the minivan with three atomic clocks and drove us up a mountain just the prove general relativity. http://leapsecond.com/great2005/tour/ http://leapsecond.com/great2005/tour/
- bkraz 6y agoThanks for the really interesting link! Posts like this are why I read Hacker News.
- mulmen 6y agoI appreciate the commitment to the bit to get WA vanity plate 9192MHZ.
- CamperBob2 6y agoSadly, WA no longer allows digits on vanity plates at all. I was hoping to get 6835 MHz, but no such luck...
- toast0 6y agoIs it that digits are prohibited or that four digits followed by three letters is prohibited? When that photo was published, WA was still running sequential plates as three digits followed by three letters; since then, they ran out, and they chose three letters followed by four letters. When that runs out, they will most likely switch to four numbers followed by three letters, so it makes sense to reject personalized plates that match the future series of sequential plates.
- mulmen 6y agoYou can have numbers on a WA vanity plate. You can't have 4 numbers followed by three letters. Of course the WA DOL site is a web app that doesn't support deep linking. You can get to the web app to check plate availability and rules here: https://fortress.wa.gov/dol/extdriveses/NoLogon?Link=PersonalizedPlate https://fortress.wa.gov/dol/extdriveses/NoLogon?Link=Persona... You may have to visit https://www.dol.wa.gov/vehicleregistration/sppersonalized.html https://www.dol.wa.gov/vehicleregistration/sppersonalized.ht... first.
- prox 6y agoI wonder if we can measure gravitational waves with the articles setup? I mean gravity and time are linked afaik?
- CamperBob2 6y agoNo, the effect of gravitational waves is far too small. Those have to be detected by watching for actual movement.
- ChuckMcM 6y agoWhen I first learned about this in college it really really bothered me. (obviously it still does to some extent) That time is not constant on a scale that lets us measure it from space vs the earth much less from upstairs to downstairs is somehow deeply unsettling. If you're traveling at 10 m/s as you go out of the gravity well you go faster and faster because time speeds up, but your velocity per unit time stays the same. Something that is really hard for my brain to wrap around in any meaningful way. During some radio work this became actually a thing in that if you're doing time-of-flight measurements of originating RF energy and one receiver is in a platform flying above and one is on the ground, at high time resolutions you start having to correct for difference in the rate of time. This is definitely something you have to do if you want to get really accurate time from GPS satellites. So freaky it hurts.
- frutiger 6y agoIt didn’t bother me so much when I finally understood that the duration perceived by an observer is simply equal to the path integral of distance along their worldline. When you think about it, you will realise there’s almost nothing else it could reasonably be.
- aaomidi 6y agoI don't get what this means at all. Can you try to Eli5
- BlackFly 6y agoTo figure out how far a distance you traveled to get to my house, I need to know which path you took. To figure out how long a time you traveled to get to my house, I need to know which path you took. Our ordinary intuition is instead, "To figure out how long a time you traveled to get to my house, I need to know the time on my clock when you left and the time on my clock when you arrived." But that turns out to be wrong if you care about a high degree of precision or if you were traveling very fast.
- 6y ago
- umvi 6y ago> over a million billion times per second So... Over a quadrillion times per second? I don't get why people do this. Stephen Hawking did the same in his book ("X star is over a million million million million miles away"). Just give me the number straight. Breaking into millions of billions of trillions just makes it more confusing as I try to consolidate orders of magnitude.
- saagarjha 6y agoThere's a reason! It's to prevent confusion: https://en.wikipedia.org/wiki/Long_and_short_scales https://en.wikipedia.org/wiki/Long_and_short_scales
- thombat 6y agoExcept that the phrase the OP picked up on is "million billion". So is that 10^15 or 10^18?
- saagarjha 6y agoI suspect the reason is then that readers may not know what a quadrillion is.
- Avtomatk 6y agoAfter a thought experiment I was able to determine the meaning of "billion": - It can be said that there are one thousand million (1,000,000,000) - It can be said that there are ten thousand million (10,000,000,000) - It can be said that there are one hundred thousand million (100,000,000,000) But it cannot be said that there are a million million (1,000,000,000,000), it is said that there is a "billion". - Then, there may be a million billion (1,000,000,000,000,000,000) But there cannot be a billion billion (1,000,000,000,000,000,000,000,000), it is said that there is a "trillion" - Then, there may be a million trillion (1,000,000,000,000,000,000,000,000,000,000) - There may be a billion trillion (1,000,000,000,000,000,000,000,000,000,000,000,000) But there cannot be a trillion trillion (1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000), you say "quadrillion", and so on... Translating this with the google translator has been hell, every time I typed "one thousand million" and "million x" it translated into "billion", and every time I typed "billion", it translated into "trillion".
- ry454 6y agoPerhaps there's a way to use this difference in time velocity at different altitudes to boil water to rotate a turbine and make electricity?
- fsh 6y agoNo. Conservation of energy still exists in General Relativity.
- tarkus68 6y ago... when the clocks are stopped or lowered and placed back in the same "Frame of Reference" ?
- sasaf5 6y agoThis article reminded me of true atomic wristwatches [0]. If precision gets good enough one day, you could get a synced pair and give one to a friend and compare after the years who has relativistically aged faster :) [0] https://www.hodinkee.com/articles/richard-hoptroffs-atomic-watch-prototype-combines https://www.hodinkee.com/articles/richard-hoptroffs-atomic-w...
- mikewarot 6y agoRemember how there was a thought experiment where you couldn't tell the difference between accelerating at 1G in an elevator, or being in a 1g gravity field? If the elevator is more than a few CM taller than the clocks, now you can. Bolt one to the floor, the other to the ceiling. If they run at the same rate, it's 1g acceleration. If there is the predicted difference, you're in a 1g field.
- BreakfastB0b 6y agoYou can't tell the difference between 1g acceleration and a uniform gravitational field. The earths gravitational field is not uniform but radial.
- thombat 6y agoELI5 time - where would a truly uniform gravitational field exist?
- saagarjha 6y agoNowhere. Gravity is just inherently radial. (But if you have a very large spread it can look fairly uniform, of course. Especially if your measure of “flat” is actually curved to the same radius.)
- aardvark179 6y agoNowhere in the real world, but that’s okay since we are dealing with thought experiments. An infinite plane of mass is roughly what you’d need so that the contributions of each element add up to a uniform field.
- mhh__ 6y agoNowhere, i.e. if you are in the falling elevator the tennis balls will fall downwards if it's uniform but any real gravitational field (apart from something of infinite radius) will make them converge gradually towards eachother as they fall towards the CoG
- User23 6y ago
- erikig 6y agoStand-up Maths did a really good (and quite self-deprecating) video of both the Special Theory of Relativity the General Theory of Relativity and how they explain time dilation that helped my brain make sense of what it was having a hard time understanding. https://youtu.be/Z4oy6mnkyW4 https://youtu.be/Z4oy6mnkyW4
- ergwwrt 6y agoThere is something about weed that can slow down time, but your ability to learn is hindered too. Question is, how to slow down time and be able to learn a language overnight..
- immmmmm 6y agoWhat is even more intriguing is that this tiny deviation is responsible for you being attracted to Earth :) In weak gravitational fields like on Earth, Gravitation is only a time distortion.
- avsteele 6y agoI've had people incredulous at time dilation effects in relativity. I give them the example of this having been directly measured in the 70's. There, they put one clock in the lab and another on a jet and flew it around a bit. https://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experiment https://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experim... Also, high-resolution GPS requires SR and GR corrections to work. This is a working technology.
- basicplus2 6y agoThe real clincher is that your toes are older than your nose