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location Williamsburg, VA
age 24
visits member for 1 year, 8 months
seen Feb 26 at 3:15

Theoretical Physics PhD Student


Feb
25
reviewed Approve suggested edit on Does the uncertainity principle violate the law of conservation of energy?
Feb
23
reviewed Reject suggested edit on Does electron in wave form have mass?
Feb
22
answered Soft brehmsstrahlung classical computation
Feb
21
comment On the distinction of past and future: could one theoretically reverse direction of particles and cause time to appear to go backwards?
I think you have the wrong expectation for your answer "it is possible". By the wording "it is", you seem to be thinking of a physical process that would reverse time. But that's not at all what the equations predict. What is true is that if you flip the sign of time (it's actually somewhat more complicated than that) and the sign of charge and then the sign of the spatial coordinates, the equations of physics will look exactly the same. That's all time-reversal means.
Feb
21
comment Measurement of quantum state
Ah, now I understand what you're asking. That is a good question and after thinking about it for a bit - I am not sure of the answer. I suggest making a new question on StackExchange titled something like "Is an ensemble of spin eigenstates equivalent to an ensemble of superimposed states?" Then ask the question you just asked in the comment above this one.
Feb
21
comment Measurement of quantum state
If I understand you correctly: you are asking whether an ensemble of spin eigenstates such that 50% of the ensemble is spin up and 50% of the ensemble is spin down is equivalent to a single particle in a superposition of spin up and and spin down? If that's your question, then the answer is no. An ensemble is many particles. A single particle is one particle. They are very different systems.
Feb
21
reviewed Approve suggested edit on Are metals more heavy due to the Earth's magnetic field?
Feb
21
reviewed Reject suggested edit on Defining electric potential energy
Feb
21
comment Measurement of quantum state
Yes, I know what a statistical ensemble is - I just don't see how that changes what I wrote.
Feb
21
reviewed Approve suggested edit on Is time dilation real?
Feb
21
answered Is time dilation real?
Feb
20
comment Measurement of quantum state
I don't understand your first sentence. As for a "hidden-variable"... That concept is in regards to the probablistic nature of quantum mechanics. Just because an observer lacks information in making a prediction does not mean there is some fundamental hidden variable in your theory. For example, if we tried to predict the orbit of Mercury yet didn't account for the small deviation due to Venus, this does not mean that the fundamental laws of gravity have a hidden variable. It just means we didn't account for all the interactions.
Feb
20
reviewed Approve suggested edit on How to find the center of mass?
Feb
20
answered What Does it Mean for an Extra Dimension to Have Size?
Feb
20
reviewed Approve suggested edit on Energy of a damped oscillator
Feb
18
reviewed Approve suggested edit on Eigenvalue spectrum of $L_x+iL_y$
Feb
17
reviewed Approve suggested edit on Translation Operator for Position on Momentum
Feb
17
comment Gossip in Physics
+1 for the title
Feb
17
comment Would a collapsing Universe have the density of water?
The density is the total mass $m$ divided by the volume $v$ where the volume is just the volume of a sphere with radius equal to the Schwarzchild radius. From the formulas you quoted, you should be able to get the density as a function of mass and then plug in the mass of the universe (which is not really a well-known number either, but current estimates put it on the order of $10^{53}$ kilograms.
Feb
17
comment Would a collapsing Universe have the density of water?
mixing water with water is NOTHING like two black holes merging. As I mentioned, the density is proportional to the inverse mass squared. Thus if you have two black holes, one with massses $m_1$ and $m_2$, then the density of the merged black hole will be proportional to $\frac{1}{(m_1+m_2)^2} \neq \frac{1}{m_1^2} + \frac{1}{m_2^2} \neq \frac{1}{m_1^2}$ so we see that if one of the black holes has the density of water, the merged black hole will not. (note: I included the last $\neq$ to show that even if you could sum densities, the merged black hole would still not be the density of water.