Measuring energy of photon to within some accuracy

AI Thread Summary
To measure the energy of a photon with an accuracy of 10^(-15) Joules, the discussion highlights the relevance of the Heisenberg uncertainty principle, which relates energy and time through Planck's constant. The initial attempts to solve the problem involved considering the relationship between energy, frequency, and wattage, but these approaches were deemed inadequate. The realization that the uncertainty principle is key to deriving the necessary time measurement was a breakthrough for the participant. This emphasizes the importance of understanding fundamental physics concepts when tackling such problems. Overall, the discussion underscores the connection between energy measurement accuracy and quantum mechanics principles.
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Homework Statement



Estimate the minimum length of time needed to measure the energy of a photon to an accuracy of 10^(-15) Joules.

Homework Equations



E = hv, where v is the frequency of the photon and h is Planck's constant in J*s

Watts = Joules/second

The Attempt at a Solution



I can think of two ways to get the units to work out right, but I'm fairly certain they're not right. One would be to ignore the specific frequency of the photon, assuming that E is proportional to Planck's constant in J*s, and dividing to obtain an answer in seconds. But that seems unreasonable to me since the wavelength of the photon should plausibly matter.

The only other thing that comes to mind straight away is to somehow utilize the definition of watts, to determine how long it would take to get some wattage, but I don't feel that this is right, either.

What am I missing? I'm sure this is a simple, 30 second problem, I'm just having a mind block... :rolleyes:
 
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Are you certain you need to use E = hv?
I think this is a problem dealing with the Heisenberg uncertainty princple, relating energy with time and Planck's constant. Maybe you should read up on it?
 
aha, that's perfect! I can't believe I didn't even think of it. I knew I was missing something easy. It's easy to derive the uncertainty principle with commutators, too, in case one has forgotten that as well. Thanks!

(See what 4 months of break from school does to the mind?? )
 
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