swansont Posted November 8, 2015 Posted November 8, 2015 The probability of each just happens to be that way? i have no problem with the inherent randomness and its exponential decay rate. It depends on the instability of the nucleus. In general, larger decay energy means shorter lifetimes (true in atomic systems as well) for the same kind of decay. 1
StringJunky Posted November 8, 2015 Posted November 8, 2015 It depends on the instability of the nucleus. In general, larger decay energy means shorter lifetimes (true in atomic systems as well) for the same kind of decay. Thanks. That makes sense... it is a completely random process then.
geordief Posted November 8, 2015 Posted November 8, 2015 Is it important to decide whether randomness or determinism is fundamental to the working of the universe? Will this always be a chicken and eģg question? Is our understanding bound to be provisional and applicable to the domain in question?
StringJunky Posted November 8, 2015 Posted November 8, 2015 Is it important to decide whether randomness or determinism is fundamental to the working of the universe? Will this always be a chicken and eģg question? Is our understanding bound to be provisional and applicable to the domain in question? This is maybe a false dichotomy because it looks, to me, the two processes are parallel phenomena.
studiot Posted November 8, 2015 Posted November 8, 2015 (edited) As regards the decay, the is a difference between the rate of decay and the decay itself. The rate of decay tends towards the exponential curve as the number of trials tends to infinity. The decay itself is random. This mean that if you lined up 1,000,000 U238 atoms and i pointed to number 1093738 in the row it's decay or not would occur in a totally random fashion. That particular atom could be stable for longer than the age of the universe or it could decay in the next second, and you have no way of predetermining which will occur. That is also why we can construct a clock from radioactive decay, as I said earlier and why this process can also be used to show the need for a time coordinate as well as measure it. Length is not involved, only number. Edited November 8, 2015 by studiot 1
michel123456 Posted November 8, 2015 Posted November 8, 2015 In many atomic clocks you are not measuring the wavelength of the emitted radiation; there actually is no emitted radiation being measured. (in others there is, but you are just counting photons rather than doing a wavelength measurement) No, not really. The period is set by the length of the pendulum, not the size of any of the gearing. You, in effect, count the number of flips (more technically you measure the interference signal between a local oscillator that arises owing to the flips so that it's not a discrete number of oscillations). That's how passive microwave atomic clocks work. Is it possible you don't know as much about atomic clocks as the certainty of your posts implies? But how is it then possible to be sure, as you are, that a distance is involved? Counting gives you a number. Without units: a number How do you insert the units (of time)?
swansont Posted November 8, 2015 Posted November 8, 2015 Counting gives you a number. Without units: a number How do you insert the units (of time)? It takes a set amount if time to complete an oscillation.
StringJunky Posted November 8, 2015 Posted November 8, 2015 It takes a set amount if time to complete an oscillation. How do the hyperfine transitions happen? Are they induced by an external source?
swansont Posted November 8, 2015 Posted November 8, 2015 How do the hyperfine transitions happen? Are they induced by an external source? They can happen spontaneously from the upper state to the lower (e.g. The 21cm hydrogen radiation in the universe) or it can be induced, e.g. by absorbing a photon.
StringJunky Posted November 8, 2015 Posted November 8, 2015 They can happen spontaneously from the upper state to the lower (e.g. The 21cm hydrogen radiation in the universe) or it can be induced, e.g. by absorbing a photon. Cheers. The oscillation rate of the caesium atom, do you set it or control it for consistency, or do you just fire as many photons at it as you can and that's the rate?
michel123456 Posted November 8, 2015 Posted November 8, 2015 (edited) It takes a set amount if time to complete an oscillation. So you are counting how many oscillations in .... one second? as measured by a grand-father clock? Edited November 8, 2015 by michel123456
swansont Posted November 8, 2015 Posted November 8, 2015 Cheers. The oscillation rate of the caesium atom, do you set it or control it for consistency, or do you just fire as many photons at it as you can and that's the rate? Nature sets it, though you can modify it by a small amount. Of course, if you're trying to measure the frequency then you have to account for all of the modifications. Such as E and B fields, radiation, gravity. So you are counting how many oscillations in .... one second? as measured by a grand-father clock? Doesn't matter, though the more you count the smaller the relative error. Some measure for milliseconds, some measure for hundreds of milliseconds.
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