It's more inconvenient then resetting your regular clock every year... How do you set a reminder for every few million years... What do you set a reminder on, for every few million years... In 10 thousand years, everything presently including our bones will be dust...
I hate when people do this. If you actually bothered to watch the entire video, it’s only five minutes, he will literally explain it to you piece by piece and you will understand it and can stop making these stupid comments.
Tiny advancements and discoveries really stack up. One person couldn't do it, but together the global scientific community can do mind blowing things over time.
The mark of a great, nay brilliant teacher, ..taking complex subjects and making them both easily understandable , and entertaining. Thank you , once again Bill. :)
Makes Bill Nye look like the slacker guy. This guy is obviously a skilled and knowledgeable engineer who knows his stuff and stays out of camps he isn't qualified to prance around in.
ThatOneEngineeringStudent Walk the talk! Make your own atomic clock then come back to us and show the world how, with your high school level alone of chemistry and physics, you really grasped it all 👌🏻
I just wanna say I LOVE your videos!! Thank you for putting these out for the world to learn... I love the engineering perspective you give on things, you've made me look at a cell phone differently ever since I'd seen that video. Keep up the good work!!
"The way that atomic clock amazes me... let me explain with how the very first one worked... I'll start with Jello." - You sir are a comedian and a scholar.
not sure how people don't follow this guy, he's explaining the stuff incredibly clear and as simple as possible, i mean, i'm from finland i understand everythign he's saying..., i went to school tho, did u? ;)
GPS calculations also have to factor in general relativity for accuracy. 1) The velocity of the satellites slows down their clocks AND 2) Their position within Earth's gravitation field speeds up their clock. Without these corrections the results would be off by a hundred meters laterally and thousands of feet vertically.
This happens because the physic laws is related to the frame of observation. (General relativity) The error actually with not correction is some cm/sec.
Did Einstein consider the atomic clock (or analog clock) in his relativistic time dilation because of gravitational distance? How do these two devices are differentiated against gravity?
So it's not just me? BTW, Mark Hamill is also the voice of the Joker. Has been for twenty years. Batman: The Animated Series (and any cartoons, films and games related to it), the first few "Batman: Arkham…" games, and DC Universe Online to name a few.
Bill I love your videos and put a link on line every friday to one of them for my students. However, watching series 4 you seem to have lost your sense of humour. Bring back the fun quips at the end at least please. They are still brilliant but leave folk with more of a smile if you let us see your smile. Thank you for all you do.
I'm a bit tired and I am not sure if I got everything immediately, but I'd like to ask how long it lasts before you're going to need to change a part for maintenance of such a device.
No moving parts and no exposure to outside air combined with microscopic scales means that, discluding being shoved into the center of a brick of C4, the atomic clock never needs any fixing.
But then how is this related ot the SI definition of a second or the caesium standard? From Wikipedia: "A caesium standard or caesium atomic clock is a primary frequency standard in which electronic transitions between the two hyperfine ground states of caesium-133 atoms are used to control the output frequency." It also says that a second is defined as exactly 9,192,631,770 transitions of those two states. I don't see how that number of transitions between the low energy state and the high energy state is important for the functioning of this atomic clock.
From what I remember from physics class is that the SI units is determine by the time light takes to travel a certain distance. Since light is a constant, a frequency or pulse using light can keep a measure of change which is time. A long time ago Galileo measured time using his heart pulse.
I'm almost clicked on the link for that book but, I'll wait to have couple more videos down. Those references for the book are getting more interesting with every video though....
the jello really effective to me. i have watched various videos with the same topic but I don't understand them well. the jello helps me to get the idea better. thanks
You say "the most accurate of atomic clocks", and though I know this is pedantic, you'd really rather say "the most *precise..." Accuracy of a clock is in how you set it. Precision is its timekeeping abilities, that it will stay perfectly consistent. If you don't reset your clock over Daylight Savings, it'll be inaccurate by 1 hour, but it could still be perfectly precise for thousands of years.
For instance, my clocks and watches are mostly very imprecise (especially my watches; they're super cheap, but fun), but they're all set very accurately, because I'll wait upwards of a minute just to set them exactly to the second from my computer or phone, so that they're all withing a couple seconds of eachother. Insofar as the source time I get from those is accurate, so are the rest, though some may veer off time after awhile.
Fascinating. But don't we need to use an even more accurate clock to know that we calibrated this one correctly? Wouldn't we need one that loses 0s in a quintillion years to determine that this one loses 1s in 138,000,000 years?
That's a good question. I think that is done theoretically. The definition of one second is theoretical. So error of the practical clock is estimated compared the theoretical definition of one second.
johnnytremp Yeah I know that definition is about counting the oscillation of the atomic states of cesium but the practical problem is about error that builds up over time in the clock. So what I wanted to say is that a perfectly accurate clock is not needed to estimate the accuracy of another clock. We should just know the definition of the second. They just do the math and calculate the probable error.
Great video. The GPS is actually experiencing time travel while in the space, the time difference should also be added in order to get the precise location.
Is anyone else confused by the illustration? At 3:45 he says circumference of a circle but highlights the surface area. Also the illustrated location is inside the surface area, but should be somewhere on the circumference. So what is being said is correct and the illustration is misleading since the overlapping parts of two spheres should indeed be the circumference. Or am I missing something here?
Thanks. Good video by the way. You can maybe make an update with the Galileo system (or future GPS updates) which has an even more precise method to measure time. No quartz involved.
A GPS receiver needs *THREE*, not "at least four" satellites to locate its positron on the Earth. And the "one satellite to correct the time of the receiver, three to locate its position" is utter BS - time is deduced from the location solution even with only three satellites available. If four satellites are available, a 3D location + time will be computed (latitude, longitude, altitude, time). If only three satellites are available, the solution will be 2D so altitude will not be computed - but the location and time will (latitude, longitude, time). This is basic stuff widely available in books and online for many years, there is no excuse for spreading wrong information on a presumably technically-oriented RU-vid channel.
corisco tupi You need four satellites for accurate measurements of position. Of course, you can get a position with only three satellites and possibly only two, but do you know why? Three satellites will result with two points and you have to choose which one is probably the right one. You make assumptions. You can, for example assume that you are, on average, about 6371 km from the center of the earth and take that as basic altitude. But that isn't always true. This is an average value that will be wrong most of the time, for example when you are on a mountain. When you are closer to the poles you will be 6357 km from the center of the earth and near the equator it will be 6378 km. If you have some cheap GPS receiver it will, of course, make that assumption and probably get a result that is somewhat right but still off by a bit. But if you are in a plane you need precise results and assumptions of altitude won't work. You need all four sats visible to calculate position, altitude and time. The fourth sat increases the accuracy of your position and gives additional data about it, with only three you are just making a wild guess and hope it's right. Technically you can also make a good guess where you are with only two sats in the sky but it will be horribly inaccurate. TL;DR You are wrong. You can't get a position out of three satellites. You either need a fourth satellite or make an assumption of your height.
MrEyecikjou Sorry, you are wrong. First off, you *CANNOT*get a position fix with two satellites, the minimum is three. Also, the difference from a position fix from 3 satellites to 4 is that the former gives a 2D position (no altitude information so the fix will be on the geoid surface, approximately sea level - but latitude and longitude WILL be acurately given), while with 4 satellites you get 3D (lat, long, alt). Of course, the more satellites, the better the accuracy but this holds true for any increase, not just from 3 to 4 satellites. I.e., 5 satellites gives a better accuracy than 4, 8 is better than 7, etc, assuming the satellite geometry at the moment and receiver location is adequate.
corisco tupi If you make a few more assumptions you can work out a position with only 2 sats, it's just VERY inaccurate. And you always will need an altitude when calculating with 3 satellites, as 3 sats resolve to 2 possible positions, additionally the position itself is less accurate.
My impression is that the "losing 1 second over millions of years" just illustrates the accuracy of the clock. It's like saying 1 mile per minute vs. 60 miles per hour. The accuracy of losing 1 second per x million years is the kind of accuracy you might need for applications like GPS. Bottom line, I think you're right: we don't really expect to use the same device over millions of years.
Good explanation of Cs clock but suggests that example unit shown in beginning of video uses the same principle. It does not. Feedback control for Rb cell is quite different.
Yes, slower satellite clock tickrate can correct for time dilation. What about the variance in speed of light, and refractive index of the atmosphere depending on the angle from the device to the satellites? I guess you could compute and correct for that with enough to make it negligible?
The intersection of a circle and a sphere occurs at two points, not one as the video says. That's why you need the fourth satellite, to narrow it down to a single point.
I've watched that part over and over again. I can't believe I heard that part so wrong. 1. I misheard. You are correct. 2. Yes you clearly did, but by the looks of the "walkthrough" of how a position is defined you only explain three satellites. 3 satellites = 2 points. 4 satellits = 1 point.
One of the proves of theory of "Relativity" effect , as "atomic clock" has very accurate time device , and show us very clearly the effect of "time dilation" if you travel long time at high speed . you can watch this on tv documentary "The illusion of time" by Prof. Brian Greene.
Why not use the discarded higher energy atoms at the first magnet as well? Maybe they can be redirected to a second clock for fail-safe or calibration?
First eevblog and then mikeselectricstuff featured YT teardown videos on the cesium clock modules used for cellphone sites. The latter pretty much shredded his unit by opening up EVERYTHING. Go watch those to learn more.
If you use three satelites you will actually reduce the posible locations to two points. You can therefore either use the fact that only one of those points are located on the surface of the earth or use a fourth satelite. I didn't know how a atomic clock worked. Thank you for the clear explanation! Edit: fourth satelite.
You need four satellitles because the gps receiver does not have an atmoic clock on it; you are solving four equations, four unknowns: x,y,z, and t. This will give you the two spots - one on the earth, one off; as you note you choose the one on the earth.
What's even more amazing is that optical ion clocks now far surpass even atomic clocks in accuracy. The most accurate optical clocks now neither gain or lose 1 second in about 4 billion years.....ie. the age of the planet.
Nive video, I remember back in the days whene we hade to calculate gps coordinate in Matlab, all the classe couldn't get a fix. this is where our professor told ud that the time on the satellite is slower than the clock on the receiver du to it speed. Epic moment
I think you need atleast 4 satellites to obtain a pin point location on Earth. 2 satellites gives you 2 intersecting spheres, giving a patch of area on the geoid. 3rd satellite reduces this area to an arc anywhere within this area. and the 4th satellite pin points your location on the arc.. Please correct me if I am wrong. I love your videos..keep going :)
Three satellites narrow your position to either of two points (not an arc) where the three spheres intersect. In a truly void space, you would need a fourth satellite to know which of those two points is your actual location. In practice, though, one of those points will be nicely on the surface of the Earth while the other will be far out in space and/or moving impossibly fast, so a little common sense can decide which one is the correct one. In essence, the Earth becomes the fourth sphere.
as the engineering guy said the fourth satellite is used for time. In a perfect world with no time errors you need three satellites to solve three equations containing three variable, xyz of receiver. Fourth satellite gives a fourth equation to solve delta t, or time difference or in other words a time correction. A combination of Satellites A,B,C,D using only 3 like ABC, BCD, ACD produces three receiver locations that will need to converge down to one solution using multivariate Newtons method ie it's an iterative method to converge to one solution
