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Originally posted by DenyObfuscation
What evidence is there that biological processes are slowed?
Time is the movement of particles in an atom
researchers at the National Institute of Standards and Technology (NIST) in Boulder, Colo., registered differences in the passage of time between two high-precision optical atomic clocks when one was elevated by just a third of a meter or when one was set in motion at speeds of less than 10 meters per second.
www.scientificamerican.com...
Originally posted by DenyObfuscation
reply to post by Biigs
Time is the movement of particles in an atom
What does that actually mean?
Look at this
researchers at the National Institute of Standards and Technology (NIST) in Boulder, Colo., registered differences in the passage of time between two high-precision optical atomic clocks when one was elevated by just a third of a meter or when one was set in motion at speeds of less than 10 meters per second.
www.scientificamerican.com...
Is this an example of actual TIME differential between the clocks or just a difference in timekeeping accuracy caused by changing conditions? They are not both "accurate" as only one would be capable of keeping proper time, say with respect to a sidereal day.
They are perfectly accurate. When subjected to speed through space or gravity they are always as accurate and never "incorrect".
Under the International System of Units (via the International Committee for Weights and Measures, or CIPM), since 1967 the second has been defined as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom.[1] In 1997 CIPM added that the periods would be defined for a caesium atom at rest, and approaching the theoretical temperature of absolute zero, and in 1999, it included corrections from ambient radiation.[1] This definition refers to a caesium atom at rest at a temperature of 0 K (absolute zero). Absolute zero implies no movement, and therefore zero external radiation effects (i.e., zero local electric and magnetic fields). The second thus defined is consistent with the ephemeris second, which was based on astronomical measurements.
en.wikipedia.org...
That's a very complicated question to answer. The answer is sort of yes and sort of no. As always, the devil is in the detail.
Originally posted by DenyObfuscation
There seem to be some tight limits on that definition. I don't think atomic clocks are "automatically" accurate. They need to be calibrated for their conditions, no?
If there's no gravity, it won't work, which hopefully is obvious in this diagram, since gravity pulls the cesium through the microwave cavity.
FIGURE 3: Gravity pulls the ball of cesium atoms back through the microwave cavity. The microwaves partially alter the atomic states of the cesium atoms.
I would slightly amend your statement about calibration...it's not so much a calibration issue. I'd say the clock must be designed to operate in the environment in which it's intended to be used.
I'd say the clock must be designed to operate in the environment in which it's intended to be used.
You did just cite the study where velocity and gravity were independent variables and they saw each effect, here: www.abovetopsecret.com...
Originally posted by DenyObfuscation
I'm thinking that maybe velocity alone wouldn't have an effect. Like I said before, all velocity we've observed in experiments occurs within gravity fields and maybe it's actually inertia(?) that causes the dilation rather than speed.
This explains why the temperature constraint mentioned in your previous source isn't such an issue, because it's how the measurements are made with this type of clock, at near absolute zero.
There are numerous laser cooling techniques, but cesium fountains generally implement a scheme known as optical molasses. This technique exerts a damping force on the atoms by using three pairs of identical oppositely directed lasers (Fig. 16). The lasers are tuned to a frequency slightly below the optical resonance of the atoms. Atoms at the intersection of the six laser beams are cooled to a temperature of 1 μK or below in a few hundred milliseconds. As if they were moving through thick molasses, the cold cesium atoms slow down to about 1 cm/s, as opposed to their ~100 m/s velocity at room temperature. This allows a large sample or “ball” of atoms to be gathered together and confined in one place.
Originally posted by DenyObfuscation
Actually it's the other way. A clock ticks slower in higher gravity.
Originally posted by Angelic Resurrection
Originally posted by DenyObfuscation
Actually it's the other way. A clock ticks slower in higher gravity.
If that was the case, the universe simply wouldnt be.
Because an observer on the ground sees the satellites in motion relative to them, Special Relativity predicts that we should see their clocks ticking more slowly (see the Special Relativity lecture). Special Relativity predicts that the on-board atomic clocks on the satellites should fall behind clocks on the ground by about 7 microseconds per day because of the slower ticking rate due to the time dilation effect of their relative motion.
Further, the satellites are in orbits high above the Earth, where the curvature of spacetime due to the Earth's mass is less than it is at the Earth's surface. A prediction of General Relativity is that clocks closer to a massive object will seem to tick more slowly than those located further away (see the Black Holes lecture). As such, when viewed from the surface of the Earth, the clocks on the satellites appear to be ticking faster than identical clocks on the ground. A calculation using General Relativity predicts that the clocks in each GPS satellite should get ahead of ground-based clocks by 45 microseconds per day.
The combination of these two relativitic effects means that the clocks on-board each satellite should tick faster than identical clocks on the ground by about 38 microseconds per day (45-7=38)! This sounds small, but the high-precision required of the GPS system requires nanosecond accuracy, and 38 microseconds is 38,000 nanoseconds. If these effects were not properly taken into account, a navigational fix based on the GPS constellation would be false after only 2 minutes, and errors in global positions would continue to accumulate at a rate of about 10 kilometers each day! The whole system would be utterly worthless for navigation in a very short time. This kind of accumulated error is akin to measuring my location while standing on my front porch in Columbus, Ohio one day, and then making the same measurement a week later and having my GPS receiver tell me that my porch and I are currently about 5000 meters in the air somewhere over Detroit.
Originally posted by DenyObfuscation
Originally posted by Angelic Resurrection
Originally posted by DenyObfuscation
Actually it's the other way. A clock ticks slower in higher gravity.
If that was the case, the universe simply wouldnt be.
Well it is the case and yet the Universe still seems to simply be.
One more time, just for you. The clocks on GPS sats run fast despite their increased velocity relative to Earth. Being in an orbit higher than 1900 miles, the net effect of the decrease in gravity allows the clocks to run faster. That's just the way it is. If you disagree then please explain why.
ETA: Why do you think the Universe wouldn't exist just because clocks tick slower in higher gravity?
What does the behavior of a clock subjected to different conditions have to do with TIME?edit on 17-3-2013 by DenyObfuscation because: (no reason given)