Probability in quantum mechanics

[@Zfaza54]

Mr. Carlson, your clear, concise videos on QM are extremely valued, thank you for taking the time to make them and share them with the world! I am a senior physics major in a well known university and with true sincerity I can say your lectures are contributing more to my understanding than class time and in person instruction. That speaks to your exceptional teaching abilities as well as to the changing face of education at all levels. Thanks for being a positive force in the world (in all coordinate systems!).

[@dk0r51]

10:28 I think the answer is (b). Precision indicates an ability to repeatedly obtain the same value from the same measurement. Assuming that the probability to find the particle in each plot is 1, then the area under each curve is also 1. To maximize precision we could minimize the area below the P-versus-x curves while maximizing the value of P. Perhaps I'm mistaken. Comments?

[@zeeshanchaudhry3324]

I think you are right, but I'm not quite sure of your reasoning. I arrived to the same conclusion via strictly viewing these plots through the lens of statistics. The precision would correspond to the span or range of the data (meaning the domain over which the domain over which the function the P(x) exists) and the accuracy (though not relevant for answering this question) is the related to the difference between the average (or mean) value of the distribution and the true value. By the latter, it should be (b) since the domain it covers is small, so there is a larger precision with respect to the mean value. All in all, the many measurements that are being made are roughly close to the same value; and the same cannot be said for the other choices. Regardless, the area under the curve should be 1 in all of these graphs, otherwise they just wouldn't be indicative of a probability function.

[@dbf72829]

@@zeeshanchaudhry3324 he has probably graduated by now and now perhaps he teaches these topics so I think he got his answer a long time ago lol

[@dbf72829]

Bro what you doing now? It's been a long time? What our future holds??

[@dbf72829]

@@zeeshanchaudhry3324 one year huh You commented this before covid ironic

[@brno322]

where can we find the answers to the questions at the end of these videos

[@No-oneInParticular]

Spoiler alert: It's b

[@lovelymarga]

Thank you!!! I’m grade 9 and we are learning this at school, I never understood it when my teacher was explaining but you made it very clear. Thank you very much mr. Carlson

[@deltalima6703]

Those grade 9 teachers are always sloppy with QM.

[@katgirl3000]

This and esp the end is a Wonderful description of the statistical interp of ψ and I loved the approach to the wave function collapse on measurement! Looking forward to the other lectures!

[@Lucas747G]

is it B?

[@vishakhawasule6083]

Thankyou sooo sooo much Mr. carlson U r a saviour we have semiconductor physics and quantum mechanics in 1st yr in engineering and it is really difficult but U made it much better and easily understandable .....❣thankyou

[@chonchjohnch]

Lmfao my professor directed our class to these videos and I was already subbed

[@6thMessenger]

I’m just beginning to learn about QM, so forgive me if my question is horribly ignorant... You mention that the measurement of a quantum particle create a new universe, or what I’ve been calling a probability timeline. It seems to me that probability is a product of the wave function within the quantum space. So, gravity seems to be the byproduct of the compression of quantum space within an object. The more compressed the quantum space, the higher the gravity of the object. Time, it seems, is also a byproduct of the wave function, which would explain the slowing of time the nearer you are to a high gravity, object. So, could a black hole basically be a blind spot in our observable probability caused by the absence of quantum space within that object? And if an object no longer has quantum space for the probability wave function to exist, does that object become a certainty?

[@paulj8213]

You explained this very well. I am grateful. Thank you.

[@bonbonpony]

07:57 What experiment shows that this is not the case?

[@gyorgydudau]

The wave function collapses and becomes narrow, right? Could that possibly have any links with the idea that particles are different when unobserved and when observed, or that you can only know the velocity or the position but not both, or quantum superposition? Or maybe it's just a coincidence.

[@apm77]

9:30 "the interpretation issues in quantum mechanics are really fascinating" ... and Einstein's complaint with QM was all about people's failure to engage with them. (BTW, obviously this summary of the many worlds interpretation is crude, because it can't be anything else without first covering entanglement, but it doesn't claim to be anything other than crude so that's OK.)

[@drisal]

Great video. One could ask: why is the imaginary part of the quantum wave function necessary? It makes no intuitive/rational sense. And the answer is: without it, things just don't work. The equations don't "add up" to give quantitative physical predictions. Bohr said: Everything we call real is made of things that cannot be regarded as real. If quantum mechanics hasn't profoundly shocked you, you haven't understood it yet.

[@montassarzaghdoud4107]

Thank you Dr Carlson for these videos. However, I would like to discuss the measurement and collapse technique. I think that it is too crisp to pass from probability curve to 1/0 around a specific expected ball or energy position on a given position space. My question is : is there a chance for a possible ignorance ? if yes then dual 1/0 doesn't well work?

[@deltalima6703]

Universe does what it does. It does not care what you you think it should do.

[@saksdaniel819]

Very interesting presentation

[@mishima3991]

i feel very high after researching QM for 5 hours.....what is real?

[@No-oneInParticular]

...No more

[@jacobvandijk6525]

@ 4:10 These functions have different outcomes: a real number and a complex number. In my simple world this means you can't draw them indepently in one graph (what's on the y-axis then???). Only the sum of the two can be drawn, because that's a complex number (psi). But then again, the squared modulus is just a real number (so what's psi doing on the y-axis???).

[@markuspfeifer8473]

If by „you can show mathematically that ‚the particle was at c all along‘ cannot be the case“ you mean Bell experiments, you’re wrong. Bell experiments only rule out interpretations that are both local and real at the same time. Moreover, this depends on a certain formalization of local and real that does not necessarily capture your intuition about locality or realism.

[@cgiarch3623]

Ok, so, why do we take ψ to be a complex number in the first place? in waves, we do it only to make the calculations easier and then we take the real part as the wave equation. Why not do the same here? "We don't have to because ψ is not a measurable quantity" is not a reason. We don't not have to either. And this end's up us having to square the complex to get a probability, which obviously gives a different result than if we just took the absolute of the real part, so surely we must select the better way, that which gives the closest to the observed results at least. So, is that the case? was it a matter of a better fitting to the data or was there a pre-thought reasoning behind the choice?

[@mannmann2642]

So find the range in between the area to this display and solve it with probability

[@kibby881]

is this Borns rule?

[@Dyslexic-Artist-Theory-on-Time]

Do you think it is logical that if the future is unfolding relative to the atoms, if we look down at the individual atoms we will find probability? This is an invitation to see a theory on the nature of time! In this theory we have an emergent uncertain future continuously coming into existence relative to the spontaneous absorption and emission of photon energy. Within such a process the wave particle duality of light and matter in the form of electrons is forming a blank canvas that we can interact with forming the possible into the actual! The future is unfolding with each photon electron coupling or dipole moment relative to the atoms of the periodic table and the individual wavelengths of the electromagnetic spectrum. As part of a universal process of energy exchange that forms the ever changing world of our everyday life the ‘past’ has gone forever. At the smallest scale of this process the ‘past’ is represented by anti-matter annihilation with the symmetry between matter and anti-matter representing the symmetry between the future and the past as the future unfolds photon by photon. In such a theory the mathematics of quantum mechanics represents the physics of ‘time’ with the classical physics of Newton representing processes over a period of time, as in Newton’s differential equations. In my videos I explain how this process is relative to temperature and the phase changes of matter.

[@No-oneInParticular]

Fascinating

[@TheCriticalAppraisal]

That C was there all along cannot be excluded 100% so shouldn't be scribbled out. There is a cognitive bias towards a non-deterministic Universe, and theories such as superdeterminism , although are unpopular, are equally as viable. It may have been more open minded to say "There are some experiments that bring serious doubt on the 'C was there all along' theory"

[@aabbccxxyyzz000]

Helpful

[@buckrogers5331]

I wonder why people keep saying the measurement is not easy to understand when folks have built the bloody instruments. No as if they are just trying their luck?

[@turboleggy]

Dank

[@mechanicclemont4799]

Collabse (x) Collapse (o)

[@jamesdolan4042]

I am having an existential crises?

[@lowersaxon]

Colla b se? Collapse has the meaning of to fail also. That seems to me a more profound interpretation. The wave function fails to give meaningful answers.

[@prometheus5770]

How can the universe split 😂😂😂

[@rummanmuhammad927]

STOP GULPING CANDY SPIT NOW AND THEN, OFTEN & OFTEN..BUT GOOD JOB OTHERWISE..U DESERVE THE BEST..JUST QUIT THE UNCONTROLLABLE CANDY GULPS..

[@etienne7774]

The universe splits I think is a dumb interpretation. Zero evidence for that. There is one physical universe but there are other spiritual dimentions the Bible talks about. View Howard Pitman. Your thoughts and intentions contain energy that can have effect on sub atomic particles, if they exist. What do you think of theoria aposthasis videos?