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1587 clicks; posted to STEM » on 25 Oct 2021 at 3:56 AM (5 weeks ago)   |   Favorite    |   share:

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That is incorrect

Sure thing, Peggy.

/nice sweater BTW

It makes sense.  Spacetime is warped by mass.  more warp, more difficulty flowing.

At the risk of sidetracking the giggity...

After correcting for non-gravitational effects that could shift the frequency, the clock's frequency changed by about a hundredth of a quadrillionth of a percent over a millimeter, just the amount expected according to general relativity.

When I was at CU-Boulder [the place where this experiment happened, yay!], during a Junior year electronics lab the professor called us all over to show us a minor experiment he had set up.

It was a digital frequency counter connected to a quartz crystal oscillator.

"Look at this, look at how many digits there are on the display."  There were like 14.  Few other meters in the lab have more than 5 or 6 digits.  Most have 4 or less.

"Now notice how many are changing, varying due to precision limits."  One.  One digit, the least significant, was flickering back and forth between two adjacent values.

"Notice how many digits there are, and how many are changing on this one."  It was a digital multimeter, measuring the resistance across a precision (1%) resistor.  There were four digits, and the two rightmost ones were slowly changing across a range of about 20 parts per thousand.

"We can measure frequency and time far, far more precisely than any other physical quantity.  When you design experiments, try to choose your parameters so that you make measurements using time or frequency.  Not temperature.  Not resistance.  Not voltage... in fact, all of those other measurements are actually measuring current or voltage in some fashion.  We can measure those, at best, to a few parts per million.  But time, and therefore frequency, we can measure precisely to less than one part per trillion.  And it's continually getting better."

I have never forgotten that moment.

/1986 iirc

That's not what she said.

James - Laid (Version 3) [Official Video]

leeksfromchichis: It makes sense.  Spacetime is warped by mass.  more warp, more difficulty flowing.

Your mom has so much mass, she warps spacetime relative to the earth.

Atomic clock stuff.

NASA Tested Deep Space Atomic Clock For 2 Years, Here's Why

That depends. Is she massively overweight?

How many beers have I had?

Does this remain true if you're a power bottom, like me?

You may last longer, but the probability of something breaking is higher.

eKonk: Does this remain true if you're a power bottom, like me?

Not sure, what happens when you run out of power?

bughunter: At the risk of sidetracking the giggity...

After correcting for non-gravitational effects that could shift the frequency, the clock's frequency changed by about a hundredth of a quadrillionth of a percent over a millimeter, just the amount expected according to general relativity.

When I was at CU-Boulder [the place where this experiment happened, yay!], during a Junior year electronics lab the professor called us all over to show us a minor experiment he had set up.

It was a digital frequency counter connected to a quartz crystal oscillator.

"Look at this, look at how many digits there are on the display."  There were like 14.  Few other meters in the lab have more than 5 or 6 digits.  Most have 4 or less.

"Now notice how many are changing, varying due to precision limits."  One.  One digit, the least significant, was flickering back and forth between two adjacent values.

"Notice how many digits there are, and how many are changing on this one."  It was a digital multimeter, measuring the resistance across a precision (1%) resistor.  There were four digits, and the two rightmost ones were slowly changing across a range of about 20 parts per thousand.

"We can measure frequency and time far, far more precisely than any other physical quantity.  When you design experiments, try to choose your parameters so that you make measurements using time or frequency.  Not temperature.  Not resistance.  Not voltage... in fact, all of those other measurements are actually measuring current or voltage in some fashion.  We can measure those, at best, to a few parts per million.  But time, and therefore frequency, we can measure precisely to less than one part per trillion.  And it's continually getting better."

I have never forgotten that moment.

/1986 iirc

When I was in grad school, we had a prof who worked on atomic clocks, and had a large, ultra-high precision display of the current time mounted prominently over his lab door.  His TAs, therefore, gave him a pretty hard time when he was late to class.

Ambitwistor: When I was in grad school, we had a prof who worked on atomic clocks, and had a large, ultra-high precision display of the current time mounted prominently over his lab door. His TAs, therefore, gave him a pretty hard time when he was late to class.

I hope the prof's response was "precision and accuracy are two different things."

eKonk: Does this remain true if you're a power bottom, like me?

Ask yourself how many times your top let go before you did.

bughunter: At the risk of sidetracking the giggity...

After correcting for non-gravitational effects that could shift the frequency, the clock's frequency changed by about a hundredth of a quadrillionth of a percent over a millimeter, just the amount expected according to general relativity.

When I was at CU-Boulder [the place where this experiment happened, yay!], during a Junior year electronics lab the professor called us all over to show us a minor experiment he had set up.

It was a digital frequency counter connected to a quartz crystal oscillator.

"Look at this, look at how many digits there are on the display."  There were like 14.  Few other meters in the lab have more than 5 or 6 digits.  Most have 4 or less.

"Now notice how many are changing, varying due to precision limits."  One.  One digit, the least significant, was flickering back and forth between two adjacent values.

"Notice how many digits there are, and how many are changing on this one."  It was a digital multimeter, measuring the resistance across a precision (1%) resistor.  There were four digits, and the two rightmost ones were slowly changing across a range of about 20 parts per thousand.

"We can measure frequency and time far, far more precisely than any other physical quantity.  When you design experiments, try to choose your parameters so that you make measurements using time or frequency.  Not temperature.  Not resistance.  Not voltage... in fact, all of those other measurements are actually measuring current or voltage in some fashion.  We can measure those, at best, to a few parts per million.  But time, and therefore frequency, we can measure precisely to less than one part per trillion.  And it's continually getting better."

I have never forgotten that moment.

/1986 iirc

At the risk of being both "that asshole" and being shouted down as a conspiracy nut:

I had a professor in college who did something very similar to this to demonstrate the amazing precision of atomic clocks and GPS based timing devices. He had five different handsets on a table and was showing us how their clocks were all synchronized so precisely...

Until he realized the clocks werent synced at all, varied by about 2 minutes, and in frustration turned them off and said something like "Well, they're SUPPOSED to be synced. You get the idea."

I never forgot that either. Make the margins for success wide wide enough, and failure ceases to be an option.

akallen404: bughunter: At the risk of sidetracking the giggity...

After correcting for non-gravitational effects that could shift the frequency, the clock's frequency changed by about a hundredth of a quadrillionth of a percent over a millimeter, just the amount expected according to general relativity.

When I was at CU-Boulder [the place where this experiment happened, yay!], during a Junior year electronics lab the professor called us all over to show us a minor experiment he had set up.

It was a digital frequency counter connected to a quartz crystal oscillator.

"Look at this, look at how many digits there are on the display."  There were like 14.  Few other meters in the lab have more than 5 or 6 digits.  Most have 4 or less.

"Now notice how many are changing, varying due to precision limits."  One.  One digit, the least significant, was flickering back and forth between two adjacent values.

"Notice how many digits there are, and how many are changing on this one."  It was a digital multimeter, measuring the resistance across a precision (1%) resistor.  There were four digits, and the two rightmost ones were slowly changing across a range of about 20 parts per thousand.

"We can measure frequency and time far, far more precisely than any other physical quantity.  When you design experiments, try to choose your parameters so that you make measurements using time or frequency.  Not temperature.  Not resistance.  Not voltage... in fact, all of those other measurements are actually measuring current or voltage in some fashion.  We can measure those, at best, to a few parts per million.  But time, and therefore frequency, we can measure precisely to less than one part per trillion.  And it's continually getting better."

I have never forgotten that moment.

/1986 iirc

At the risk of being both "that asshole" and being shouted down as a conspiracy nut:

I had a professor in college who did something very similar to this to demonstrate the amazing precision of atomic clocks and GPS based timing devices. He had five different handsets on a table and was showing us how their clocks were all synchronized so precisely...

Until he realized the clocks werent synced at all, varied by about 2 minutes, and in frustration turned them off and said something like "Well, they're SUPPOSED to be synced. You get the idea."

I never forgot that either. Make the margins for success wide wide enough, and failure ceases to be an option.

A man with one atomic clock knows what time it is. A man with five atomic clocks is never sure.
-- Ancient Chinese Proverb (updated)

I want to know about the o-scope they measured that with

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