# Quantum Mechanics and Entanglement

I'm hearing a guy ( Tom Cassidy ), which supposedly has a master in physics, saying that what we expect in a physical experiment ( for example, observing some particle ) can actually interefere with the workings of the experiment. Is he distorting quantum mechanics terms and facts to use it with his purpose ( what we think internally can actually interfere with the external world ) ?

Here is more or less of what he said :

We can measure an electron to be at two different places at the same time.And we can also observe an electron as a particle or as a wave depending on what we set the experiment to observe.. It makes no sense but WHAT we are actually looking for, creates the result. Because its all the experiment, it's not humans thinking "oh, it would be nice if the results came that way ... ". What we expect to see, we see ... then we design the experiment in a different way and expect something else ... and thats what we see ! It makes no sense, thats why we don't understand Quantum Mechanics. The scientists know this. When you are doing a quantum mechanics experiment, you are looking to observe somthing as a particle, you open up a box ( figurative ) and what you see is a particle. What you are looking for, it knows you are looking for .. thats how quantum mechanics works .. An electron will exist in the bottom of an energy well, it has really low probability of getting outside of that energy well ( the energy required is insane ) but every so often electroncs magically tunnel into the walls ( energy walls ) .. Why do they do it ? I don't know ... and anyone who says they know why it works, they are lying ... they don't know, nobody knows why quantum mechanics is the way it is ...

Then some people might directly think that Quantum Mechanics is like Law of attraction : "You think and it happens ". But it's not as simple as that.What we found is that this is the way of how results are found in quantum mechanics. Quantum mechanics works for the very very very very small , but recently , just last week i was reading a study which says that Quantum Mechanical entanglement effects have been observed in much larger things ... groups of atoms as high as fifty. Last week, there was a study in the New Scientist in the UK which reported that quantum mechanical effects have been observed between pairs of diamond crystals. And the relation of size between Diamond crystals and our brain is a lot smaller than the difference between particles and diamond crystals. Now, the final question is ... how big are thoughts ? It's so when you start thinking " its actually real ". You talk of people between the law of attraction and they say, oh its so mambo-jambo, now they can think its ideas are actually based on science ...

So, is there at least some truth to it ( even if its not true that quantum mechanical effects work for a pair of diamonds ) ?

Thanks a lot in advance.

EDIT : Just did some search and it seems like the final part of the top answer in this link Quantum Entanglement - What's the big deal? might suggest some kind of influence of one electron in another electron, physically distant from it"

• I posted an answer, but in retrospect, I'm not clear on what the question is. – DanielSank Jun 27 '14 at 21:43
• I just wanted to know if theres some truth to the claim that the observer actions ( even his thoughts ) can actually influence the results of the experiment ... – nerdy Jun 28 '14 at 3:11

## 1 Answer

We can measure an electron to be at two different places at the same time

That's already a dodgy statement. If you measure the position of an electron you'll find it at one place. You actually can't do any single measurement to completely map out a quantum state, so saying that we can measure an electron to be in two places at once is kind of wrong.

What you can do is:

1. Prepare electron in state $|\Psi\rangle$.
2. Measure something (eg. position) on the electron.
3. Prepare the same electron (or a different electron) in state $|\Psi\rangle$ again.
4. Go to step 2.

If you repeat this procedure you can reconstruct the state $|\Psi\rangle$ from your many measurements. Note that you rely on the assumption that you prepare the same state $|\Psi\rangle$ each time.

And we can also observe an electron as a particle or as a wave depending on what we set the experiment to observe.

The way measurement works is a lot less complicated than folks like to pretend. You have a system under study, $S$. You have a measurement device $M$. When you do your measurement you are physically interacting $M$ with $S$. This has to be represented by an interaction Hamiltonian:

$$H_I = H_S \otimes H_M.$$

You can actually show that the basis in which $S$ collapses is just the bases that diagonalizes $H_S$. So, this whole business about whether an electron acts like a wave or a particle is completely explainable and not weird. It is dependent on how the mesurement is done, but in a completely quantifiable way.