Is The Future Predetermined By Quantum Mechanics? 

Out of all the episodes of Space Time, this one is the one that left me feeling like a caveman the most.

"Wubba lubba dub dub" Damn Matt, i'm so sorry to hear this, I hope you feel better in the Future. I know these are tough times but i just want you to know that we will always be here for you :)

I've learned so much from this show. And yet, every time an answer spirals out from an exploded question, two more new questions also are discovered. I love it, thank you for all you do at PBS Space Time.

I love the face he makes when he reads a line that kind of breaks the brain. Like he's trying to keep his head from exploding. It's the best.

3:21 "The wave function is real". Actually the wave function is complex. :-)

“We’ll have plenty of time for time, another time, on space time.” You’ve gone too far this time!

I'm learning more and more about this (bit of advice, watch more than one video on the same subject and rewatch videos too) and it is honestly changing the way I understand my own existence more than anything else ever has.

Sometimes I think our physics is just from human perspective and at times is limiting to our overall interpretation of the world. I think an advanced enough society may look at physics outside of their own perceptions which would probably mean they’re beyond war as conflict solution.

So it doesn’t matter what Lottery numbers I pick as long as I pick them at the right time and have enough orange cats watching me. Got it.

Col. Sandurz: Now. You’re looking at now, sir. Everything that happens now is happening now. Lord Dark Helmet: What happened to then? Col. Sandurz: We passed it. Lord Dark Helmet: When? Col. Sandurz: Just now. We’re in now now. Lord Dark Helmet: Go back to then! Col. Sandurz: When? Lord Dark Helmet: Now! Col. Sandurz: Now? Lord Dark Helmet: Now! Col. Sandurz: I can’t! Lord Dark Helmet: Why? Col. Sandurz: We missed it! Lord Dark Helmet: When? Col. Sandurz: Just now! Lord Dark Helmet: When will then be now? Col. Sandurz: Soon.

I find fascinating I believe I can grasp what's going on the last two episodes even though I studied philosophy and not physics. These series are probably the best content now available on RU-vid. We are fortunate to live in a time where such quality content is available for "free" (not considering you still have to pay for the internet service most of the time). Thank you very much Dr. O'Dowd, you've become a science heroe for me.

I've always felt like this waveform collapse is a quantum "tree falling in the forest" and the uncertain fuzziness prior to observation is just another way of saying "we can't be sure, but probability states there should be a noise".

I have PhD in Chemistry and absolutely love this stuff. Having taken quantum physics, as an undergrad and P. Chem as a grad student, much of this content is vaguely "familiar", and in my mind I put it together with everything else floating around in there. What blows my mind (even more than the amazing content) is the mass appeal and genuine interest from non-scientists. This is high level stuff; if I have a PhD and it's only sorta making sense. Kudos to anyone seriously interested in this without the STEM background - I imagine everyone's mind is blown in a different way, based on their background....but everyone's mind is definitely blown by what's being suggested here (and in all these videos).

Yes, this episode was pre-determined to make my head hurt.

I'm glad I found this episode. Yesterday I had the thought that maybe time has always existed and time just behaves in a way that we really can't perceive like how a 2d being couldn't comprehend 3d and so forth. If all of time and space expanded from a singular point, time could be like a series of snapshots in which we can't perceive the breaks in like a picture book being flipped to make a short animation. Every possibility making up the multiverse. The big bang or great expansion being a multiversal expansion and not just our universe. I'm glad to hear others have thought up similar things.

This is absolutely one of the most interesting segments I have seen. In all of this I really do wonder if there isn't much more "spookiness" going on in how reality unfolds. Things like entanglement, synchronization, vortex math.. Etc. This was an outstanding and intriguing way to weave many other complex systems and theories together. I love that he simply posits on the wonderful possibilities. Well said.

11:46 "There are other interpretations that deserve mention, but [they don't deserve it enough to actually be mentioned]"

Me: time to go to bed. I need to get up in couple hours for work Also me: Great here we go down the rabbit hole once again

Love how this kinda glosses over the fact that a conscious observer collapse would imply a very high significance of our existence given that not everything can cause that collapse. Not quite deific but not far off given a direct impact on the shape of reality itself. Also probably why a deterministic multiversal solution feels the most right: clearly we're not gods. Despite what some people may think.

My problem with non-deterministic idea of these "unknown" qunatum probabilities, is that it is still ultimately deterministic. Think about it, if you are reading a book series and it is unfinished. From the perspective of the characters in the books, yes, the future is unknowable, but that does not mean the characters in the book get to influence the outcome of their future. All it means is that whatever force(in this case the author) that drives the future, has not made a determination yet. But that does not make the book itself non-deterministic.

Is it possible that I live in another branch of reality than my wife? So many times we cannot agree on our common past light cone...

My two year old watched this with me and was very into all the cats, saying "another cat!" and meowing at each of them.

6:47 This concept of "Relative Present" just makes "Many Worlds" way more intuitive than "Copenhagen".

I have re-seen this several times now. Its so interesting, every time i see it again i go to different places in my mind

Now I want a country singer to write a song about letting quantum mechanics take the wheel.

One thing is a certainty; I am going to watch this video.

I just can't tell you how much this presentation has changed my life. It has even started to change personal relationships. Thank you so much.

I listen to these over and over until I understand them. Thank you for expanding my mind. What a gift that could never be repaid with any crude matter, but I'll chip in some bones when I get paid. You've earned it.

When I saw the notification for a new Space Time video I knew I was going to have to click on it, so... yes, the future is predetermined.

What is mind? Doesn't matter. What is matter? Never mind. - Homer Simpson.

Doesn't the speed of light + relativity of simultaneity "fix" the 2nd example? Observers in your "present" can't gain any information that isn't within their light cone and therefore can't collapse your future wave function by learning about it from an observer in your future path. Or do I misunderstand?

I need CC english subtitle in this video, really like all your video. I've learnt so much about our universe in your channel. Thank you.

"Einstein's theory of special relativity combined space and time into one unified thing - spacetime" *show ends after 9 seconds*

"We'll have plenty of time for time next time on Spacetime." That's just brilliant writing right there.

“We’ll have plenty more time for time, another time, on space time.” Best valediction yet. 😆

Thank you for sharing this that was very interesting. I enjoyed it.

"But - we'll have plenty of time for time some other time in spacetime." Brilliant lol

What is predetermined is me watching this every week

The first 30 seconds of this video just 100% light bulbed the entire previous episode. I'm hooked.

scientist: "discovers entanglement" Will Smith's wife: I cheated because of entanglement. It's predetermined.

"We'll have time for time another time on spacetime." Goddamnit Matt.

The universe is infinitely predetermined, which is to say finitely unknowable, thus it makes no difference unless you’re outside it in something bigger and stranger.

This one of the best videos y'all have made.

Very well explained. Have wondered if them life moments when feeling uncomfortable with life direction could be anything to do with a gravity pull to your timeline but am understanding much clearer now that this concept is probably unlikely because every possiblity is happening but we are only experiencing one path of time but this leads me to another thought. If as 3d beings we can see everything in a 2d world. Does that mean they might be 4d beings that can see everything fully in our 3d world and is 4d time? One more things if time travel was possible going to the past would be going back on time line you have taken but how would going to future be decided what timeline it too when every possiblity is happening? Just some thoughts. All the best all.

That moment when a boltzmann brain is the simplest explanation.

"the answer depends on your favorite flavor of interpretation" - I'll interpret this as "nobody has the slightest idea"

"We'll have plenty of time for time another time on space time." Haha great.

The intersection of the conscious experience of a single branch with these interpretations is so alluring, as is the romantic notion of altered states of consciousness (like dreams) being an experience of these other possibilities.

Not gonna lie, this is the best explanation of 2020 I've come across so far. Something something collapsing future something.

I am currently picking up the pieces of my brain shattered through my room after my head exploded. Why do I always feel dumb watching your videos. I have a hard time understanding but keep coming back still.

I just read a book trilogy called, "The Three Body Problem." Highly recommend this book! It plays with multiple topics that this show is famous for. Also an episode about the sciences involved in the books would be epic!!

"The only totally coherent way for a non-deterministic wave function collapse interpretation, like Copenhagen, to give you an uncollapsed future, is if you're the only being doing the wave-function collapsing" But in a sense isn't this actually true, there is only _Being_ and we are all aspects of that being, experiencing itself subjectively

I spoke to my future self at age 7, and answered 40 years later ... remembered exactly on time! 🤯

If the future means watching PBS Space Time then yes, it's predetermined

What blows my mind is the tracking of all the alternate realities prior to the wave function collapse, if it even being tracked at all. What I consider tracking may be considered something else.

My first watch of this episode (years ago) went swimmingly but I've been around since the days of Gabe (seen erry episode, most several times). I sympathize/know the feeling though; the most difficult concept/topic covered here for me was (without doubt) time crystals (pretty much baffled to this day 🤷‍♂️).

What is the difference between an observer and just any old regular particle interaction? If an observer is just made of particles, and the particles the observer uses to interact are doing the observing, wouldn't that mean every particle interaction collapses the wavefunction?

"The only thing that is certain is uncertainty" - Probably someone in history

Congratulations on the wonderful graphics on the Copenhagen and Many Worlds theories.

Random thought: so if entangled particules are separated one at rest and the other moving near the speed of light and we measure the particule that is at rest, it does it means we affect the state of the moving particule in the past?

This is a great episode! This is the stuff that keeps us coming back. I've been interpreting the multi-worlds theory all wrong and it's not my fav... Thanks PBS SpaceTime! Bravo!

Matt asked for our help at the end of this episode! Hang on in there, my friend! Everything is gonna be fine!

Nice video. Philochrony is the theory that describes the nature of time and demonstrates its existence. Time is magnitive: objective, Imperceptible (intervals) and measurable.

@5:30 Yeah but what's the mechanism for us being the us in THAT branch, and not the others? Seems like (as I'd maybe expect) a restatement of the same exact measurement problem/wavefunction collapse in it's practical effect (we observe a particular outcome, we presume other outcomes were hypothetically possible) as is in Copenhagen.

It's me, I'm the one collapsing the wave function. I know I've made mistakes, especially as of late, but if you cancel me you do so at your own risk. Cheers!

I watched Interstellar (again) the other day which really messed up my mind and got me thinking about the idea of a pre-determined future...

Hi Dr. O'Dowd. 2 questions: wave function collapse seems to require observation, which to me seems to require life, so what if life never evolved? and if time causes gravity, and time is money, does money cause gravity?

So, what would be the "function" or you, me, everyone, etc ? Meaning, with either method (collapsed/non-collapsed multiverse) you or me or anyone ends up being the "path" created by us as we move through the multiverse. What would the equation be for that path? I'm not 100% sure that I asked that correctly but I hope you understood. Thank you.

Phew... heady stuff Matt. Still struggling with “if a tree falls in the forest...”.

You just made me questions my existence and reality

I dreamt of my fish, dead. The next day I saw my fish, dead. It's wave function collapsed.

It seems to me that the past can be defined by "information we are entangled with" and that the present is defined by the propagation of the wavefunction through our brains (hence the smearing, we can only form an idea of the "present" a few hundred ms after it is already the past). Although using this idea leads to the question of what exactly the present is and at what point the present becomes the past... Ultimately leading me to conclude that consciousness exists in four dimensions... and that the reason we experience the flow of time is by nature of consolidating disparate fragments of multiple presents. We actually SEE time... we exist across a narrow slice of time with non zero thickness. I really want to share that notion with somebody because it's blowing my mind.

The wave function probably collapsed, just in time, for Matt to deliver his final line, in a rhyme, before the final chime, of this episode of, PBS Spacetime.

I'm happy for the countless other me-s who lives in world where 2020 is a nice year

Love this video. Changed my life and the way I relate to my grown children. Now there are many free will choices they can make. They create the choices.

“Probability wave”, “Wave function collapsing”... I call it magic.

I was thinking about this a couple of days ago. If you consider the universe as a graph with nodes being Quantum states. You are a DFS algorithm through this graph looking for your death 🤯

Love the focus on metaphysics and philosophy these past 2 episodes. These are really difficult concepts to understand, and I appreciate seeing your perspective as a physicist. Question: What do you think about the “moving spotlight theory” of time as an explanation for the experience of the present?

Imagine that we actually live out all of our slices by re-combining our consciousness after death. That would be a nice reality of existence to me.

Very cool! and when learning this it feels very... comforting? Knowing that nothing is classical mechanics really happens randomly and everything has an effect on something else. If you choose to fly a plane, there are soo many things that that effected (That will spread out across the universe through entropy over time and create more causal chains) and all the things those causal chains that caused to make that decision. This is definitely something I would geek-out on lol. I also realized that even if the universe is deterministic nothing in the universe could ever predict it. (Which is probably the reason WHY we can't prove anything about how the universe operates) This is the same thing as the "Halting problem" where you can't make a machine that simulates and PREDICTS another one aka. The universe. This is why none of this actually matters you or any object or atom or molecule in universe because you can't change it, it's always BEEN the universe, and this is a better way to create a universe that FUNCTIONS then having things happen randomly that can actually effect you. (Like changing you're decisions or some stupid stuff like that). Because if randomness has an effect over only you're brain than why? Why can't atoms of your arm or any object float away and make everything into gas or clumps. To people who feel nervous or "trapped" by this I want to tell you that it doesn't matter, nothing can predict the future, and it's still okay to think about this though because we're just speculating and trying to change your future or gain free will doesn't mean anything. The universe is ordered and that's how it exists in the first place.

I love listening to this show, I memorize a few quotes and say them at dinner and people think I’m a genius.

Juan.

this is the BEST, I think, MOST accurate description of reality. FURTHER evidence is that it supports the axiom of choice from Zermelo Frankel set theory which is critical to generate modern mathematics.

Just a thought: Surely by using relativity to fast forward to the future and past universe, quantum mechanics' unpredictability adds increasing amount of uncertainty the more you fast forward away from the present. When rewinding the motion of the expanding universe back to the big bang, surely quantum mechanical uncertainties over this long period of time mean that all predictions we have about the big bang are very uncertain??

Thought experiment regarding the collapsing of wave functions: You're in your car at a friend's house about to leave but scrolling through your playlist to find the correct one before leaving. As you drive through the city, every traffic light of every f***ing cross street is red. But you know that it's not always the case as you've also ridden the "green wave" at the same time through the same streets. So, if you had not scrolled through your playlist, you would have been more lucky? Maybe. Well, aside from the fact that it already happened, you've already chosen your path but on the other hand, the traffic lights don't care. They run in their pattern, regardless if you scrolled through your playlist, drank an extra drink or went to the restroom one extra time (just to be safe). If you think...well...but your actions were random, right? I can kind of argue that with: What thought process made you search for that song? Why did you go to the restroom one extra time? Those behaviors most likely arose from your past experience...your brain connections you made that one time, you had a very uncomfortable ride with a nearly exploding bladder. Or you know that the ride is much more enjoyable with that one specific song you have in mind. If you trace back your past, you might come to a reason for every move you've made in life. The big ones like moving to a new country or the small ones like releasing some extra fluid from your body which is a basic function of your body, determined by your biological functions which is ultimately in your DNA. Which means that all those specific proteins in your body formed exactly the way (from the big bang to the present) until that very moment you were particularly annoyed at the wave of red lights which made you comment with a novel at this episode of Space Time. Hence, I do think that everything is predefined but that doesn't mean that we're just waiting for the asteroid crushing into the earth. Everything in the universe (even every atom) is a variable and our brain has plenty of those "int i" variables (if you ever programmed in C like myself). So because we have powerful brains who built powerful computers, we can think ahead and can predict things like asteroids very well and maybe have a defense strategy by the time it might happen. And then the Armageddon movie becomes the new reality (hopefully with a better remote ignition system - poor Bruce) which still was predetermined by the universe. Well, that was something for a Sunday afternoon...I'm going to clean my appartment now.

This is the better “science of Dark explained” video I’ve ever seen

Mind blowing!!!!! Great vid

Thanks to Matt and the PBS space time team for making these great videos! This time, however I find the argument at 6:50 unconvincing. The claim that the event at the bird would collapse the future of the event at the human does not seem to me to be supported within SR. Just because the human sees the cat event as simultaneous and the cat sees the bird event as simultaneous does not imply that any of the observers see the human event and the bird event as simultanous. Actually, the human, the cat and the bird would all agree that the bird event happens after the human event, and because of this the bird event could not collapse the human's light cone. In fact, there could be no observer moving at the speed of light or slower that would see the bird event as simultaneous with the human event, since these events are time like separated. The human's event and the human's future would remain uncollapsed from any observers view. At least as far as I understand SR. Please comment if there is anything wrong with my line of reasoning, so that I could understand the argument in the video,

You forgot to mention Carlo Rovelli's relational QM interpretation! My favourite interpretation, where even the very collapse of a wavefunction is relative to the observer. I feel like it would be relevant here.

Matt, hearing you say "Wubba lubba dub dub" just about salvaged my 2020, thank you!

This is one of my biggest problems with the fundamental randomness of QM. We know for certain that one observer can see another's future in its present, so it can't be undetermined in the other observer's present. It's a direct contradiction. We need a better explanation for how realities are selected from a set of potentialities, one that explains consistency between observers. That means we need a better explanation for what happens during a measurement and "wave function collapse". But it seems these questions are prohibited among physicists, who have taken "shut up and calculate" to heart as dogma.

I understood this whole video, was just digesting it all when suddenly "we don't have time for time this time, maybe next time on space time" and it's like the whole episode never happened. All I can think is next time

I thoroughly enjoy the fact they went through the trouble of adding "meows" to the cats.

Could there be many worlds in quantum reality and one observed world in classical reality both going on at same time?

This has always been in the back of my head since i was a wee lad

I want a tee shirt that says "The wave function is real"

Sounds like the Future is in a superposition of being predetermined and undetermined.

It seems valid to think that we are constantly changing realities with respect to change in condition

Other required listening is, "Story of your life" by Ted Chiang. It has the best explanation of experiencing "present" as a being that doesn't need to limit itself to existing between past and future. And if we can imagine and calculate these 5th dimensional beings, who is to say that our interpretation of existence defines it?

What if we do the same but instead of "now" to slice the block universe, we use the path light cone as reality and as soon as they leave the cone they don't exist anymore or they exists but at an undefined time (but all observers are still equally valid)?