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Atomic Clock Turns 50
karvind writes "BBC has an interesting story on the 50th birthday of atomic clocks. The first accurate caesium atomic clock was developed at the NPL in 1955 by Dr Louis Essen. And after 5 decades In September the US National Institute of Standards and Technology (NIST) used computer chip fabrication techniques to make a small atomic clock. The final development should see a battery-operated system about the size of a sugar lump. NIST also has a page on history of atomic clocks"
It's a good thing we had atomic clocks so we could be sure it was really 50 years!
Lump of sugar has to be the oddest comparison ever...
There are exactly 42,935,718 letter sized sheets in a square mile.
I used to be obsessed with accurate clocks, still am for my servers, but after awhile its all relative anyway ;)
The more you know, the less you understand.
The atomic clock turned 49.9999999999999999999999 today!
;)
Congratulations
liqbase
It seems that more and more of everything is sync'd with this. My clock radio at home auto-updates, clock on the wall, the cellphones, my Linux and Mac PC's and cable box.
Only thing left are the clocks with a single AA battery on the wall, and at some point they are going to use the pervasive WWVB time signal that is broadcast from Colorado and operated by the National Institute of Standards and Technology
This technology has really come a long way and is deeply embedded within our lives. Especially if you consider that before the atomic clock, time varied considerably between different locales.
Newsfollow.com
That article is not precise! The atomic clock is 50.00000100121412235901293409234 years old as I'm writing this.
Four scientists, as they flip the switch on their new invention ...
... ...
#1: Gee, Ed, it looks like it works
#2: Bob, you're right! It's counting! We did it!
#1: It seems to be right on, let's fire up the chronotaph
#3: Already there, Bob, I have a solid register, five-nines. I started the paper before you hit the button.
#1: Good thinking, Stan. This is one for the record books!
#2: This is a clock for your ass, Ed! I guess we should set it now.
#4: Okay guys (looks at watch) what have you got? I'm showing a quarter past two.
There really is no market for atomic clocks. At best you will get devices that sync themselves to an atomic clock, that's located far away. Even people that do have pretty accurate clocks are always late. I find that in general, most people are late, and don't really worry too much about time in the first place. Really gets on my nerves, as i'm always on time, and always have to wait for someone.
Anthropic principle: We see the universe the way it is because if it were different we would not be here to see it.
because without NTP, we might as well be using sundials.
Anyone see that article a couple of weeks ago in New Scientist about Strontium atoms held in standing waves generated by 6 lasers? Mental. A 50 time more accurate (or something).
...the worlds first atomic wristwatch.
That's like asking how does the "clock" in your computer get set to the right time. (Not the system clock, the crystal that generates the clock frequency the electronics operate off of).
Atomic clocks just "tick", not display an actual time. They provide an extremely reliable and high frequency tick which makes them so valuable.
=Smidge=
Uh huh, that's what it wants us to think....
"This food is problematic."
Atomic clocks count the number of vibrations within an atom, so know how much time has passed to a high degree of accuracy. Absolute time however, cannot really be known, as we have no reference point to measure it from (unless we find someone who has been counting since the big bang happened!).
The standard day-to-day time system is UTC (rather mysteriously standing for Coordinated Universal Time) and it is based on the rotation of the earth. This is decided by the BIPM. As the length of a day is not precisely divisible by a second, leap seconds occasioanlly have to be added.
Atomic clocks were primarily developed to deal with former, measuring the passage of time. This turns out to be a very important and difficult problem in all fields of science and engineering. The reason is that any error is measureing the passing of time will be amplified and make all other things very wrong.
So, after using the sun, water, gears, and springs, someone finally figured out that if certain atoms were excited, they would vibrate very regularly. By counting the vibrations, we could measure the passage of time.
Now, we don't measure time in vibrations of an atom. We measure the passage of time in seconds. So how long is a second? The hand waving definition is the second is 1/60 of a hour, and the hour is 1/24 of a day, so we count the vibrations over a day, then divide by 24, and divide again by 60, that is the vibrations in a second. Of course we have to decide how to measure a day without using a clock! This can be done, and after much argument, the scientist just give up and agree on thier best guess. The key thing is that everyone agrees on how many vibrations are in a second, so we are now able to say difinitively that something takes a second, or 10 seonds, or 100 seconds, or 1.2352 seconds.
So, the measurement of the passing of time is important to science, and even important to the making sure that you don't spend an extra second in class or at work, but what does this have to do with your question, which is getting to work or class on time.
Well, ultimately that is just a decision we make. There are standard clocks that measure time in universal time(UT), which used to called greenwich mean time(GMT). This time is adjusted geographically so that 8:00 am does occur in the middle of the night in the US. And that is they key. We set the time so that 8:00 am is in the morning, and 8:00 pm is always when most good children are in bed.
How we set time, so to speak, was done by looking a the sun and the moon. You can in fact look up the data for sunrise and sunset in your area and set your clocks by this phenomemom. This is the same thing we do with calendars and seasons. Much is set around the longest and shortest days of the year. For instance, the day in which there is an equal amount of sunlight and darkness is called the equinox, and this day that occurs in the northern hemisphere, when the amount of daylight is icreasing, is curently called March 20 or 21, and is the first day of spring.
It is interesting that that while we have had accurate clocks for a long time, that is we can accurately measure a second, syncronization has a been a problem. For years we have radio signals to synchronize enabled clocks, but now with the internet we can all be on the same time. Although for some reason some clocks are still set a few minutes off in either direction.
"She's a scientist and a lesbian. She's not going to let it slide." Orphan Black
"I believe time travels slower at the equator than at the polls."
I don't know about that. When I was standing in line at the polls back in November, time seemed to drag on. Now, afterwards, it's dragging on even longer while we here in Washington State are still wondering who our governor is.
What's that? You meant poles? My mistake.
Give me my freedom, and I'll take care of my own security, thank you.
"How did they figure out how to set the clock initially? Thanks." They killed Christ. You're welcome.
No, because he's essentially correct.
In VoIP protocols, a timestamp *is* placed in every packet along with a sequence number. The timestamp is used to place the incoming audio and video packets in the correct order with regard to time. The sequence number is used to detect packet loss. So basically, sequence numbers don't help you with jitter. The timestamp is use to actually calculate the amount of jitter, so it's rather important for it to be as accurate as possible.
Show me on the doll where his noodly appendage touched you.