Quantum 101 Episode 6: Quantum Probability Explained

When Albert Einstein famously said "God does not play dice with the universe" he wasn't objecting to the idea that randomness exists in our everyday lives.

What he didn't like was the idea that randomness is so essential to the laws of physics, that even with the most precise measurements and carefully controlled experiments there would always be some level at which the outcome is effectively an educated guess. He believed there was another option.

This video discusses how probability is determined in quantum mechanics. Let's play some dice with the universe and talk about it.

Join Katie Mack, Perimeter Institute’s Hawking Chair in Cosmology and Science Communication, over 10 short forays into the weird, wonderful world of quantum science. Episodes are published weekly, subscribe to our channel so you don’t miss an update.

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[penumbraman]

The Quantum 101 series is very well done. It takes the fundamental aspects of Quantum theory and explains it in beautifully simple terms. It also mentions the known and unknown details the theory. Keep up the good work.
This material could be very useful in high school physics class to help explain quantum theory.

[RobRoss]

Einsteins comment about “God does not play dice with the Universe” is greatly mis-understood by most people. It’s important to define the “God” Einstein was referring to as the God of Spinoza, who is more of a philosophical entity than a “God” in the modern Western sense. To Einstein, “God” is simply the laws of nature. And when Einstein said this God does not play dice, he was referring to the essence of quantum indeterminacy, regarding certain quantum effects such as radioactive emission. Essentially he was objecting to the Shrodinger’s Cat thought experiment and the like.

[notenoughyettoomuch]

The quote in the beginning from Einstein, I think is wrong. From what I’ve gathered, he never actually said those words also he didn’t believe in God and traditional sense. I see a lot of people are arguing about this and just a little too caught up on it. Einstein may have believed there something more going on obviously but it wasn’t in the traditional sense of religions like Christianity, Islam, etc.

[carrieolson]

It’s frustrating to be interested and open to physics yet have so little comprehension. This shouldn’t keep my attention, they might as well be speaking Latin. But here I am. I think that if even one piece of information made sense to me, my world view may be completely different. In a positive way. I just can’t wrap my brain cells around this stuff. Grateful for those of you that can, and do.

[mkbraj]

This is something very close to the philosophy of our perspective makes our world.. what we observe becomes our reality

[MrPedalpaddle]

Excellent as always. Thanks especially for your explanation of the “wave function”

[keopsequinox]

Your videos are excellent Katie, it makes me wish Youtube existed when I was a Physics student ;)

[TheoWerewolf]

I've always wondered by Feynman required ALL possible paths to be represented in his representation... and one line in this video, that in QM ALL possible states are happening at the same time and so must be factored into the probability analysis made me go "oh... of course... that makes perfect sense". Weirdly I knew all the parts but this was the first time it came together.

It makes me rather proud that the Perimeter Institute, creating these excellent videos and doing exceptional physics, is Canadian.

[pedrosuarez]

to be exact, a pair of entangled particles is a pair of particles that, despite the uncertainty principle, we can guarantee with total certainty that they interacted at some point or shared the same origin, their properties being correlated, there is no distance communication as such in entanglement, therefore does not violate any law. In fact, if it weren't for entanglement and quantum decoherence, quantum would be nothing more than indeterminacy, those mechanisms bring order to the matter.

[richardsaglimbene]

As an avid craps player trying to learn quantum mechanics, I very much enjoyed this segment. I now have a better appreciation for Wave theory and until this episode tied it back to how i play craps. In terms if is she an actress, yes, in much same way Sagan was an actor.

[RobRoss]

Einstein was so smart he often outsmarted himself. Poor guy. He won the Noble prize for something that essentially started the whole study of Quantum Physics. And yet for the longest time he refused to accept it. Although, he did come around in the end.

[SampleroftheMultiverse]

I really enjoyed your well produced video and concise expectations.
As always for best results sample the multiverse with care. 5:33

[Dyslexic-Artist-Theory-on-Time]

Could the wave function Ψ² represent the forward passage of time itself within an individual reference frame? Light photon ∆E=hf energy is continuously transforming potential energy into the kinetic Eₖ=½mv² energy of matter, in the form of electrons. Kinetic energy is the energy of what is actually ‘happening’ the energy of motion. The dynamic geometry of this process forms Heisenberg’s Uncertainty Principle ∆×∆pᵪ≥h/4π. That is this theory represents a probabilistic future continuously unfolding relative to the electron probability cloud of the atoms and the wavelength of the light.

[ywtcc]

The funny thing about particle collisions is the uncertainty.
It's as if planes of uncertainties emanate around some center of pure uncertainty.
From this viewpoint, the only thing we're ever really certain of is uncertainty.
I fear this inverted epistemology may be inherent to a forward looking perspective in time.
Retroactively we can say for certain that something happened, it's when you start asking questions about what happens next that all the problems with uncertainties appear.
Isn't energy itself a predictive measurement? In the sense that given some set of causes, we have grounds to assume a potential set of effects.

[harryseldon]

If a particle's position and velocity cannot BOTH be determined, does that mean it DOESN'T have both a position and velocity? Or that it does and we just can't determine both? Which is it?

[afgaadf]

How can I delete this video on the playlist

[Canda-fhxc]

The music is too loud.
It is hard to hear the lecture.
Please turn the music down, or off.

[davidhobbs]

The more i learn about quantum mechanics the clear it is that it is only an approximation. You cannot have a probalistic wave function result in deterministic behaviour without some form of mechnism to convert the two, probailoty is useful as a tool to describe things with unknown mechnisms, this feela like the case with quantum mechnics.

[WingZeroSymphonics]

Great video. Neat to ponder on just how perplexing the quantum world has been for physicists and where physicists are pointing to heading forward. Playing with a one of those dice sounds like fun. 🤣

[brianegendorf]

There is no such thing as a superposition. We use the wave function to describe the fact that there are multiple paths that may unfold that we are not sure of. They don't collapse. Its just that at each moment in time, probability plays out and what wasn't sure a moment ago IS sure now. Its not so much that the wave function collapses when we observe what happens. Its that until the process is completed, the ending can't be known. So we have to observe the result of a constantly changing probability after it is no longer changing. At lets be clear, this is actually a deterministic result. Every process is deterministic. Causality just colors the results of the deterministic process. Imagine a clock that random picks a time to show you. Yes, the time it chooses is random..but the machinery that allows it to do so is ultimately deterministic in that it uses the same arm, motor, and circuitry to operate..and even though there might be a randomizer in there..the randomizer itself, is made of something mechanical or electronic that functions deterministically. If we had to wait to observe every quantum effect to occur in order to know what happens...the universe would be permanently froze. We would never get a chance to observe it. The universe is its own relative observer. Everything in the universe is relative to everything else in the universe. Or nothing in the universe would actually work. It would just basically be one big block of ice.