Recent content by Robert Shaw

Here's your previous post. "Why do you think that your macroscopic nose should have a 'quantum state' ? I cannot think of any definition of 'quantum state' that can be applied to it." Please could you clarify it with a term other than "macroscopic" which you say is indefinable.

Macroscopic was your choice of term when you critiqued my post. Now you're saying that nobody can define it. Please would you clarify your previous post with language that you feel confident about yourself.

Localisation does not exist in a qubit model. Alice and Bob are not spatial. To make them so would require a much more complex model, with position variables as well as Up/Down. Same for two qubit models. Quantum information theory studies such simple models because they lead to significant...

Closed systems are idealisations. Reality seldom approximates to a closed system. On rare occasions real systems can be created that approximate to an idealised closed system. Our knowledge of such systems is from the mathematics of the idealised closed system, for which we can write down...

Reality is too complex for physics to model. Football, a game of football, obeys the laws of physics. Physicists cannot model it however, not quantum nor classical. Knowledge is the problem. We don't know enough about almost everything to write equations. Look around you. Mostly complex...

Ok let's take the simplest quantum Hamiltonian, zero potential energy everywhere. Then form a wavepacket. Wavepackets can exist in isolated closed systems. Yet they are superpositions of energy levels

In your terminology, you are assuming that subsystems for Earth and Mars are the same. That assumption is neither necessary nor correct.

You seem to be linking "reference frame" to "unitary transformation" in a way that makes no sense in the context of my question. Of course a unitary transformation will trivially produce the result you cite. That is not the point I am making. I am talking about two Earth observers and two...

Please find some references below that appear to contradict your position:Observables can be tailored to change the entanglement of any pure state N. L. Harshman and Kedar S. Ranade Phys. Rev. A 84, 012303 – Published 5 July 2011 Observables and entanglement in the two-body system N. L...

I think I like your answer, but I have doubts that you haven't addressed. The term "specified manner" sounds reasonable and reassuring but is actually vague. "I bought it at Aldi" so it's been prepared in a "specific manner". "I weighed it on my bathroom scales" so it's been measured in a...

Knowledge and lack of it are key issues. We believe that the laws of physics including quantum mechanics are universally applicable. We don't however know how to apply them to most situations. A game of football we assume follows the laws of physics but do not know how to apply them. Almost...

So macroscopic objects do not have a "quantum state" ? Please tell me where is the point at which microscopic states stop being quantum states? I'm assuming you can give me an answer that's accurate to 10 decimal places.

I think Ballentine is correct. Limiting the term is sensible. Widening it to any procedure at all strips it of purpose. The reason why the term was introduced was to ensure replicability of the state. Any old procedure is useless...it must prepare a replicable state. Regarding the example of...

The state only has to obey: ih d|state>/dt = H |state> where H is the Hamiltonian for a closed state. This does not imply that the only solution is an energy eigenstate. Superpositions are also solutions. For example a wave packet is a multi-energy superposition of plane-wave energy...

Exactly. The system is separable from Alice Bob frame of reference. It is entangled from Martian frame of reference; as you say the Martians see different subsystems. Hence the title question for this post. The answer is that separability and entanglement are dependent on the frame of...