Basic Understanding of uncertainity principle

Take a box equipped with a shutter and a clock.The box is lined with perfectly reflecting mirrors and contains photons.The clock is very accurate and acts as a timer.Precisely at a certain time 't1' the shutter opens releasing one photon.The shutter is closed at time't2'.By making the interval 't2-t1' as small as possible we will know with high accuracy,the time when the photon escaped.therefore the error in 't' can be made as small as we please.the energy of the photon can also be accurately determined by subtracting the final weight of the box from the initial weight,and finding the energy by the mass-energy equation.Or the error in energy and time can be made as small as possible,which is a violation of the uncertainity principle!Is this argument valid?If no why?

Gedanken in QM(Will help you understand that ideas of CM should be carried over to QM with a pinch of salt)

As in a fermi gas all fermions can't occupy the same quantum state.Therefore if a fermi gas reaches 0 Kelvin only a single fermion will occupy zero energy state,other fermions will have some kinetic energy.Also as the temperature of a body is because of the virtue of the motion of the particles constituting the body,the fermi gas should have a temperature.This contradicts our earlier assumption that the fermi gas is at 0 Kelvin!
Hence,can a fermi gas ever reach 0 Kelvin?

Another gedanken on relativity

DOPPLER SHIFT AND HAWKING RADIATION

Consider an event of pair production by a photon with energy > 1.02 Mev.
(NOTE-Pair production can take place by a single photon when it interacts with a massive( as compared to itself)body.)
Now consider the same event to be viewed from a frame in which the original photon was red shifted so that its energy was < 1.02 MeV. In this frame the pair production could have taken place only if the excess energy of the electron and the positron would have been negative.This leads to the conclusion that either there exists a potential energy function which has different values in different inertial frames or the event would not have taken place i.e. the electron and the positron will still be seen as a photon from the other frame(If the second assumption is assumed to be correct also consider the case when the pair production results in Hawking radiation.)Which of the above conclusions is correct?

Priyank

Gedanken onnnnnnnn......RELATIVITY!!!!

It seems appropriate to start this blog with a gedanken on relativity,which in itself is the most beautiful gedanken in history of science.

The thought experiment is as follows-

Consider two observers near an isolated system in the form of a finite mass and finite length rod in the frame of the observer(A) at rest w.r.t the rod.The second observer(B) moves with v~c towards the rod parallel to the it and towards it.In the frame of B the mass of the rod tends to infinity while its volume tends to zero.The gravitational field of the system in B's frame is radically different from that in A's frame.This will result in different outcomes of any gravity dependent experiment even though the two observers are in uniform translatory motion relative to each other.

PS- Even though the above may seem to be silly at first to some of you,I just wanted to introduce the rest to a powerful tool of theoretical science that gedanken are.

Priyank

Greetings!

Hiya everyone!

This blog will have some thought experiments(gedanken) I come up with from time to time.