ไม่สามารถเล่นวิดีโอนี้
ขออภัยในความไม่สะดวก
ฝัง
- เผยแพร่เมื่อ 7 พ.ค. 2012
- "I Don't Think It Means What You Think It Means" examines scientific theories that have taken on a life of their own in popular culture & we help you understand what they really mean in scientific terms. Today we take on Schrodinger's Cat, the famous thought experiment by Austrian physicist Erwin Schrodinger.
Like SciShow on Facebook: / scishow
Follow SciShow on Twitter: / scishow
References for this episode can be found in the Google document here:
dft.ba/-2DJZ
How about Schrodinger's spider? you know the one that you step on, and you arent entirely sure if it is dead or not, until you lift your foot...
Except the fact that you KNOW that the force of you stepping on the spider will for sure kill it, and there is no 50/50 possibilty - you did step on the spider and you surely killed it. It's different with the atoms - they will either decay or not, and that's what creates the 50/50 possibility and the superposition. In summary, you don't know if the atoms decayed or not, but you KNOW that you stepped on the spider.
I like how only science nerds respond with a serious answer
Herkus Kaminskas And what may I ask, was the purpose of that? All you managed to accomplished was restating what the video already explained.
Herkus Kaminskas it looks like you've never step on a spider... Not only it was a joke, but you didn't understand it, there are spiders that remain alive even after you step on them, so when you step on a spider you don't actually know if it's dead or alive. (I know this has nothing to do with quantum physics, but... Whatever)
don't abuse arachnids
I learned this theory from my choir teacher. He said that there was a universe where the cat was alive and a parallel universe where it was dead and every time something happened, ever conceivable outcome formed a parallel universe.
...He then used this concept to tell us, when we messed up, that we could have been in the universe where we sang every note correctly.
That's multiverse theory
+Melvin No
No, you didn't because those doors and donkeys don't actually exist. But if they would then yes, you'd make 100 parallel universes
Your choir teacher has a very poor understanding of the Schrodinger's cat thought experiment. It was devised as a counter-example to illustrate the absurdity of applying quantum mechanics to macroscopic systems.
LOL SAVAGE
@@Monochromicornicopia while it is true that it is absurd to apply superposition to macroscopic objects, the cat is an important learning tool. Living and dead are two states that people easily recognize and the thought experiment was used to explain the superposition using familiar terms, it was never meant to literally be applied to cats or any other macroscopic objects.
However, if we assume that the multiverse theory is true, and that the cat is in fact a cat (not a subatomic particle) and that the cat has a random chance of being alive or dead, it does actually very precisely explain a point in time at which a split in the multiverse may occur. This isn't the original meaning of the thought experiment to be sure but it is a good way of explaining how a random event may lead to two equally likely scenarios becoming two separate reality streams. This is an appropriation of Schrodinger's cat that does, in its own right, make sense.
But the cat can be both alive and dead. It has nine lives, therefore it can lose one and be dead, yet still be alive with 8 lives remaining.
Checkmate, science.
+TheInnovative It would revive in poisenous gas... so I'm sorry for the cat but until someone opens the box and lets the gas out it will likely continue to die eight times more.
+anynamebutmyrealone it was actually an iron cage, therefore the cat will be fine
Publish your refutation, pal!
+TheInnovative
Me: Ok, lets see if the cat is dead or- What the heck? You're alive?!
Cat: Yah. I have 9 lives, duh. Thanks for wasting 5 of them, Brainiac.
TheInnovative unless.... those other 8 lives have already been used up... and they're still there at the same time..
These people need to understand it before saying, " just put a camera in a box or put it in a transparent box"
+Logan Perry What if you only put part of the cat in the box? Say its tail? You still have no way of seeing or observing what it is inside, but the reaction of the cat would inform us which had happened?
+Impulse Reaction ANY observation at ANY stage would violate QM's laws
+Logan Perry It doesn't work that way
The cat is both dead and alive
The observer won't know the out come until they open the box
hahaha people actually say that?
+Logan Perry It doesnt help, the very moment you put a camera means you are observing, the very moment you are observing means a superposition doesnt take place at all. So you see the cat either die or be alive which is like simple probability, so no use of a camera or transparent box.
IDTIMWYTIM: IDTIMWYTIM: Schrodinger's Cat... you're going to have to do this again, because apparently most of the commenters missed this entire part: 2:50 - 3:10
The whole point of this thought experiment is not to see if that cat is alive or dead, or even matters that the cat can observe things too but simply to point out that THERE IS NO UNIFIED THEORY between NEWTONIAN PHYSICS AND QUANTUM PHYSICS.
There are two different scales at work here, neither of which play well together. Schrodinger was trying to point out that THIS DOES NOT MAKE SENSE and that they are missing a large part of the story here.
For quantum particles, superposition works. On the Macro scale, it does not work. So, that means you (or rather the scientists back then) need to STOP USING NEWTONIAN PHYSICS TO ARGUMENT OR DESCRIBE QUANTUM PHYSICS and vice versa. ..
Let's see if that gets across to anyone... >_
Erudite So, you don't think that means what they think that means?
Erudite Oh I get it. So you're saying Isaac Newton didn't like cats. Thanks for clearing things up!
THANK YOU, FELLOW COMMENTER.
Erudite but the macro particles are also made up of quantum particles afterall then why does it not need to work???
(In my Ant Man voice) “Do you guys put the word ‘quantum’ in front of everything?”
When they say "observe", it doesn't mean a conscience person has to see the event for it to leave a superposition, observe more nearly means interact. So as soon as one thing interacts with another, it is observed.
What if the cat is experimenting with us and we are only alive when they observe us?
Danny Huang Then I guess that would make you not alive
+NeonsStyle no it would make you a cat. :p
Just like "If a tree falls in a forest and no one is there to hear it, does it make a sound?"
Danny Huang you are observing only your self because only your awareness of being here on a planet is creating that.
.
My friend and I came up with a movie idea where Shrödinger's Cat started a Zombie Apocalypse where the zombies must be observed to be stopped. The movie would contain Einstein, Shrödinger, Isaac Newton, and other various scientists. There would be a lot of math and science jokes and stuff. The idea was pretty hilarious to discuss.
I made a box for the cat and there is a film inside the box, in the film the cat is seen drinking in a cocktail bar contained in the box, but the cat is both alive and dead,
the cat- at this time - representing quantum particles.
The music for the video inside the box, which can be seen in full is by the Chinese composer Jia Guoping, if you would like to see the box go to the link: th-cam.com/video/FJ04vgzv-B8/w-d-xo.html
How’s it coming along so far?
My cat died watching this.
OR he's alive and is currently resting comfortably in your lap...
The reply did better than the actual comment
none of us can observe your cat. so if we all reject your testimony, your cat holds it's superposition and is still alive and dead, and it's fate until we see said cat, shall be at the mercy of our own assumptions, until we can make our own observations... if it is really dead, exhume the the remains, and post a pic or video.
Proof or it didn't happen, and mittens is still sipping milk while you are a cat's slave cleaning up it's poop!😁
only 5 days after like the ring
Overlord9001 I think you mean and as it can’t be confirmed if his comment was a joke or not.
Okay ... here is a topic.. Cows... yes ... cows can tell when it is going to rain. They lie down and start chewing the cud. WHY? .. when cows eat grass they are also ingestic air @ say 1 atmosphere. The outside atmospheric pressure drops causing moisture in the air to precipitate causing rain. Inside the cows 4 stomachs the air pressure is still at 1 atmosphere, thus making the cow feel bloated. Perhaps this is why cows lie down before rain falls. This should be easily testible by leading a cow into a hyberbaric chamber and slightly lowering the external pressure. What do you think?
This makes the Schrodinger's Cat theory now makes sense to me. Thank you. I also looked at it as the old fashioned 'the cat is either either dead or alive, opening the box makes no difference' but this video shows what was meant by the theory. Excellent job and I appreciate being given the full story, Traditional, Quantum, and the attempted combination of the two.
I tried 4 times to understand this experiment, and only now, after watching this video, my eyes are finally open. Thank you, SciShow . You guys are made of pure awesomness.
But wouldn't the cat be observing whether the atoms decay and break the poisonous gas? And therefore there would be no superposition?
It's all about what humans observe, not the cat
so only humans can observe things??
Yup, humans are bias towards their own species.
i'm pretty sure the cat has eyes and can therefore observe. if one person (or cat) observes something, but another doesn't, then is there still a superposition for the one who didn't observe it until they find out?
Metal Marauder
This is exactly the point of the thought experiment: Scroedinger wanted to show, that the copenhagen interpretation is nonsensical: If the cat in the box doesn't do it for you, you can imagine another human inside the box: The copenhagen interpretation is exactly the same from outside the box: The human /inside/ is now in a superposition of dead and alive...
All this goes to show is that the copenhagen interpretation is wrong, and so, another one is needed, e.g. the manyworlds interpretation.
If he superposition can't be observed and collapses once you would observe it, couldn't the cat be considered an observer, thus not allowing the superposition to form at all?
*the
Emily Angstadt Good point. My only argument would be that it hasn't been proven (at least I don't think it has) that cats have consciousness. I've heard from Michio Kaku that consciousness may cause the superposition to collapse.
the geiger counter collapses the superposition state. quantum world is a lie, you can't test it in a lab. it is just a mathematical probability
A H LongUsername There are proofs for quantum physics, if you would look it up instead of being a lazy ass, and calling it a lie.
Emily Angstadt - ok, then change the cat to a bomb.
Is the bomb exploded and not at the same time?
or is the bomb an observer?
why would the geiger counter collapse the wave function? the geiger counter and all of the environment is just made of particles, electrons like the observed one.
And of course cats have consciousness - as we speak of that usually.
A H LongUsername - You can see the probability waves with the double slit experiment. as well as the role of the observer. what are you even talking about?
Schrodinger's Cat, Schrodinger's Cat,
Where are you hiding, where is it you're at?
He gave nine lives as a quantum rat;
It's Schrodinger's, Schrodinger's Cat!
©2015 Qermaq. All tights perturbed.
+LivyLew42's Awesome Party of Videos Which Spiderman theme?
+LivyLew42's Awesome Party of Videos
I believe you're thinking of the spiderman theme song from the 1960s cartoon. :o)
#QuantumRat
Dear God - thank you - this was sending me insane how people kept insisting the cat was dead and alive - it's either dead or alive - nothing in between
The Double Slit experiment - an idea for the "I Don't Think It Means What You Think It Means"
+poweredbyaaron99 99% of internet think it porn ._.
Not even joking I cracked my phone while watching this video I should of have left it on the ground so that it would be broken and not broken at the same time lol
I always used it to mean "the outcome will only be determined once you've observed it," i.e. the principle that the uncertainty collapses once observed. I always thought of it as an illustration of uncertainty and superposition rather than an illustration of the illogical discrepancies between quantum physics and "normal" physics, even though that's what motivated the thought experiment's inception.
So far the best explanation I've seen on the matter.
Does this mean the atoms have a consciousness? How can they tell whether or not they are being observed?
Georgia B The reason quantum mechanics can't be observed is because observation has the prerequisite of interaction and said interaction cause's superposition to fail. For example, for us to see something, light must reflect off of it which is an interaction.
My Entropy Thanks!
+Georgia B Think of it like checking the tyre pressures in a car. In order to measure the pressure, your device will open the valve letting some of the air out, thereby lowering the pressure. By observing an atom, we are interacting with it, thus altering its behaviour.
+My Entropy Thanks so much! This question always left me completely confused about how observation causes anything to happen. Now it makes so much more sense!
+Joseph Boyd but won't light reflect off those particles anyway, regardless of whether there is anything to receive the light? It would still reflect off the particles, right? That is what baffles me.
Y'all should do one for Netflix and Chill
When I searched up "Schrodinger's Cat" I expected some long, boring explanation of it. Thank you for proving me wrong in both matters. Short, sweet, and a touch of humor. Nice. Subscribed, liked, favorite.
I asked a librarian if she had a book about Pavlov's dog and Schrodinger's cat. She says it rings a bell but she wasnt sure if it was there or not.
Schrödinger's Cat walked into a bar.
and Din't
A big problem with this experiment is that a cat has 9 lives ;)
john cenicola i tell you im kidding, as can be shown in my ";)" smile
+John cenicola Please tell me you're not that dumb.
the one thing that I'm so glad about is that science and the art of acquiring knowledge is being endorsed on TH-cam so heavily, with channels like MinutePhysics, VSauce, and SciShow among others all kicking around to make learning fun. So thanks, SciShow. Sanks.
You have to define "observe", in this experiment observation is defined as shining photons on it, bouncing electrons on it, or anything to this effect as "observation", or like the geiger counter, detecting particle decay.
Correct me if I'm wrong. Why do we need an "observer" to prove something exists? Why do we need an "eye" to verify that the cat is alive or dead? Wouldn't the cat itself confirm that it is alive when it can see around and lick it's paws? So consider humans in the place of cats. If the radioactive element doesn't decay, then we are alive because we "know" we *exist*. Why do you need some observer to prove that we exist?
because you (the observer) are proving existence of something to yourself not to the thing you're observing.
if you were in the place of the cat, you would know if you existed but untill someone else observed your existence, to everyone on the outside of the box your self observation would be irrelevant as they wouldn't have access to it and thus, from their point of view, you would equally exist and not exist.
It's all the matter of observation. Untill it is observed you have no way of knowing. Self-observation is also an observation. You yourself couldn't assess if you were dead or alive if you were in no position to make an observation - say, you were unconscious. Again, you would know only when you observed it (regained consciousness).
So yes, to prove something exists we need an observer.
Rozamunduszek Thanks for the insight; now that I have another doubt: Observing requires a light source and the light reflected back from the cat to our eyes which confirms that it exists. But what if there wasn't light there at all. If I were to go into a pitch-black room with black walls and a black cat there and no light source at all, I wouldn't know if the cat exists or not, even though it *is* alive. So, observation requires a light source, and is completely dependent on the light reflected back from it?
+Paneesh PunIntended you overcomplicate.
If you are able to make an observation, you make an observation.
And if you're not able to make an observation, you're not and that's it.
There is no reason to list every possible obstacle that would or could prevent you from making an observation. Because the possibilities are endless. There could be no light. You could be blind. Your other senses might be also impaired. The cat could be in a box... Yes. Cat being in the box has just the same effect on you being able to observe it as there being no light. It ALL comes down to your ability to make an observation.
And the ability to make an observation itself? Easy. If you can observe something, you can; and if you can't, you can't (including all the possible obstacles)
Rozamunduszek Alright man thanks.
This isn't important, but the "o" in Schrodinger has an umlaut. It's Schrödinger.
I wish I had a name with an "umlaut" in it!
@@tonyboyle354 Ok Töny…
There's no umlaut on my keyboard brobeans
@@Monochromicornicopia Here you go: ö Ö
What device do you have? You should be able to hold down the “o” and it’ll give you options. If not, you can copy and paste the above 😎
@Mister Winkybluff
Doesn't work and can only hold one item in copy - not gonna permanently reserve it for umlaut lol
I've only been really into science a couple years and I was amazed when I understood this wasn't just some isolated thought experiment but a quantum physics one. I mean, science communication and teaching are doing something wrong (well, we're doing it wrong) when most people know something about quantum physics without realizing that they do.
Best description of Schrodinger's cat I've ever come across.
I had a dead cat, I put it in a box. It didn't worked!
It's not the act of a sentient being observing that collapses the quantum probability field, but the interaction with it. The decaying atoms flinging their particles out to the Geiger counter is the interaction that collapses the probability field.
Peter Martinson Nope. The interaction interpretation has long since been replaced...
Nope, you're wrong.
That's helpful isn't it? Why don't you explain?
Peter Martinson
Yes, yes alright...
Actually, I've already explained it in other threads on this video (a recent one started by Jordan Kelly, and one about 9 month ago with Alex McNally), but basically the reasoning is (briefly) as follows: Since physics isn't "local" (as seen by the bell inequality experiment), the interaction interpretation implies that, if I meassure one of two objects in an entangled superposition, a "signal" is sent out from the obejct I'm meassuring to the entangled object to insure that the wavefunction of that object is suitably collapsed (these are the "spooky actions at a distance" as Einstein called them). The mechanism for these interactions would have to be spooky indeed, since they are able to travel instantaniously to any part of the universe that is entangled with the meassured object, and change them, and _only_ them, in just such a way as to match the observation - one might go as far as to call these interactions "incredible" ;).
If you want a more thorough explanation, please try and read the other threads that I've mentioned above...
I don't see how any of that contradicts what I said. The probability field can still collapse on one particle and its quantum entagled partner.
The theory of relativity limits the transmission of information faster than light, but there is no information transmitted in quantum entagled states being determined.
There is a problem if you take the interaction picture seriously: If particles (or whatever) collapses due to you interacting with them, how can the quantum objects be non-local? Interactions are always local so you interact only with one part of the entangled object, and so, if interaction is neccesary for collapsing wavefunctions, how do the other parts of the entangled system get interacted with so that they know to collapse? Instantaniously? (whatever that means...)
The short answer is: we have experimentally seen this.
One of the experiments that baffled physicists into studying quantum mechanics was the double slit experiment (there are some good videos on here of it). The act of observing the state of the electrons actually did change their behavior.
But the math says so too, and math is king. The cat experiment is actually one way of showing this property. By observing the box, we eliminate the superposition simply because we see the state of the cat.
Scishow not only educates me but just cheers me wayy upp :DD
wait a sec if alternate worlds are possible with different physics , does that mean somewhere there is a actual pony land :D
The laws of physics are probably not different in different worlds.
Of course. The point is that we don't know. In this reality, I don't know, you don't know, but in that alternate world, we could both be frolicking around in pony world. *I just don't know.*
Ellie Sara How did you make the text bold? o.O
in infinite alternate universes, every possibility is contained. So yes.
Does that mean that somewhere there is a X that contains Y (and of course wearing A hats and B suspenders)
no matter what you can imagine, there are a set of laws that can be designed to fit that world. This has more to do with an outcome from mathematical modelling than actually observable physics.
verbw002 Use * around the word(s) you want to be bold. Use _ for italic and - for strikethrough
Spoiler ! It's not about the cat
Excellent video, I have heard a lot of Schrodinger's Cat explanations but none of them explained the point of the experiment, now I got it.
Best and easiest to understand explanation I've heard of this theory thus far!
In another reality I'm not commenting. In another other reality I'm not even watching. In a second another other reality I'm not interested in science and I'm an old hag. Scary stuff!
What makes you think the cat was ever alive anyway? Maybe the only living thing is you, and everything else is your mind trying to make sense of the world by adding other life forms and materials. Which is why things can only be measured when observed...
ZeaMoore4 nigga u goin way too deep
When she says "go deeper"
ZeaMoore4 Quantum mechanics are things that can NOT be measured when observed. Not the other way around. And this has been proven by an experiment.
The observer has to be external relative to the system in question. So depending on the system you look at, you're right. Those are all valid observers. The Geiger counter observes the system of the radioactive material. So when the radioactive material decays (or doesn't), the counter ticks (or doesn't). However, if you expand your system to include the counter, then the hammer would be the observer. And you can continue to expand the system to include components. (cont'd)
Thanks for sticking with me on this, it's hard to find anyone around who likes thinking about this stuff, most just roll their eyes and wander off! I think big science is amazing. I see that I am one step behind on this stuff, I must read up on dark energy I think.
Do you have a video about Pangea?
Gee, Shrodinger's Cat is a much less thoughtful theory than I initially imagined. So it's a theory whose sole purpose is to explain a lack of conclusion. Seems pointless, but I guess there's no other way to explain something you don't understand than explaining WHY you don't understand it.
+Graphomite It's not a theory at all. It's a thought experiment to clarify some misconception.
All I know is that somewhere there is a cat in a box, and I extend to get him out.
It's actually just a joke erwin schrodinger was writing to einstein back in the day about how crazy quantum mechanics was. He was basically saying in a joking way that if these ideas of quantum mechanics are true then lets apply them realistically to a cat and a poison vial to show how crazy this whole field of physics was.
You don't know whether it has decayed or not decayed until you observe it. This is the idea of quantum superposition, that something is and is not at the same time until it is "observed" (this doesn't necessarily mean looked at with eyes, it could be a camera or other apparatus). This exact principle is what is applied to the idea of electrons as both waves and particles until the point of observation. To answer your question: it will do both because you cannot know which it has until you see it
Meassurement: An observation if "the observer" can tell what the result is, otherwise an entanglement.
It is not obvious that the double-slit experiment is relevant: In that, one immediately observes whether the beam was in a superposition or not, but in this cat-experiment, everything happens in a box, which _prevents_observation_. That is the key point: In CH, this means that everything in the box simply entangles with everything else (cat,Geiger counter,atom), rather than "collapse".
My biggest question is why was the cat necessary? Couldn't you just have the hammer break a piece of pottery if the Geiger counter went off?
Because who doesn't like cats. They're fluffy and adorable. Why not.
+w4tif The cat is not necessary. It was added just to highlight it's absurdity. We all understand intuitively that cats can't be dead or alive at the same time.
+Kucas Mukas He explained the purpose of the cat. "To prove that the quantum world doesn't mesh together with the-well ya know like normal world"
Adam Holliday He didn't say that at all. He said Schrödingers 'point' wasn't blahblah... Not the point of the cat, but the experiment. All nicely taken out of context and misplaced. I guess now is the time we embark on an endless journey of pointless arguments. Einstein first came up with this experiment and there was no cat or any other kind of living creatures involved. Einstein got it wrong and Schrödinger got it right? Don't think so buddy.
www.pitt.edu/~jdnorton/teaching/HPS_0410/chapters/quantum_theory_measurement/index.html
Energy cannot be created nor destroyed. Where would the energy come from to create an entire universe just so a cat be alive or dead?
Jordan Fischer essentially the energy is only conserved along a single timeline, so all that is required is for the energy in each of the new universes (after the meassurement) to be the same as the energy of the universe before the meassurement (or, strictly speaking, the average of the energies of the new universes should be the same as the "old" universe)
*****
How exactly do we know dark energy exists for a fact. I am pretty sure you are mistaken. Dark energy and dark matter are a good explaination for what we see in the cosmos but neither has ever been observed or mathematically proven to exist.
Norman Gurtler
*All* we have concerning dark matter and dark energy is observations. Noone has a really good explanation for what dark matter is (it's thought to be a new fundamental type of particle, but _that_ hasn't been proven yet), and noone has any explanation at all of the nature of dark energy - as such, we don't _know_ that they obey energy conservation. How could we? We don't know how dark energy/matter is created or how (precisely) they interact with the rest of the universe. However, I'd be shocked if they didn't both obey the conservation of energy: It's been a universal principle for everything observed in the universe so far...
listen m8, u need 2 reed teh bibl and jezus wil show u teh way. ty god 4 my life. amin.
*****
No we know there is accelerated expansion, and dark energy is a good way to explain what we see. Dark energy is not known to exist by an stretch. We simply don't know enough about the universe to say for certain.
Change the scenario slightly. The
cat is inside the box and there is the same atomic emitter and receiver. But in
my box, there is a vile of acid (which
would also be broken when the receiver reached the designated count from the
emitter) rather than poison. Needles in the box, mounted under the cat
across the only space within which it would have to move would ensure that it
remained standing while alive. If it were to fall as a product of its death
when the acid vile is broken (releasing
the acid fumes), it would be skewed by the needles and affect the mechanism
holding the acid vile which would cause it to tip over and spill its contents
on the floor of the box.
When the acid finally eats
through the bottom of the box, it is because the cat is deterministically dead.
There is no wave function to collapse. The observation is forced by the string
of deterministic events ending in the acid dripping to the floor after having
eaten through the box. The observation is after the fact not prior as in the
original scenario and thus, it cannot be defining of that event in any way or
measure. Can anyone resolve this, explain the merits of it or the lack?
Thank you for the explanation I've been looking for since Sheldon Cooper uttered Schrondinger's cat.
Silicon Valley brought me here.
Ryan Kennedy hahahhaha
Ryan Kennedy hahahhaha
I still don't get it :(
When nothing is interacting with the cat (you aren't looking hearing it etc) the universe "forgets" about the cat because there is no need for the cat to exist. it is only when something interacts with the cat that it needs to exist so the universe makes a descision, is it dead, or alive?
Wow! Thanks. That did help actually :P
+Evan Hagen Oh my gosh, I sort of understood it after the video but your comment made it so much more clear. It's like a lightbulb went off in my head just now, haha.
+Evan Hagen I agree with the others, thank you for the insightful comment.
+Evan Hagen This was a vivid explanation. I think I comprehend it better now.
Here's some stuff that works for my limited brain: Physicist friend said we cannot observe quantums like cats without interference, they don't emit anything we can measure without getting in the way. So in order to measure a quantum state, we fiddle with it, like you touch a ball to see if it's still there but when you do, you apply energy to it, so it starts rolling off. That's why you can only know how fast a quantum particle is or where it is but never both at the same time. Weird but cool.
The point of the Cat "experiment" is that the quantum wave has to collapse at some point. If it never collapsed then even opening the box and looking at the cat wouldn't fix the cat in a particular state, instead it would envelop you into the superposition.
As I understand it, we have learned through our attempts at creating quantum computers that the superposition is actually a very unstable state for a particle to be in. Any sort of quantum noise will collapse it which is why room temperature quantum computers have eluded us. They have to be kept super cold so stray particles don't collapse the qubit states prematurely.
Exactly what does this experiment prove? That a multiverse exists? I am sorry, but I have watched hundreds of videos and so many interpretations that I still don't get this paradox. -.-
J Lander It doesn't "prove" anything as such, it just shows that there are some very weird consequences to the copenhagen interpretation (which was prevalent at the time) of quantum mechanics. While schrodinger was proven wrong in assuming that the cat (or more precisely, a large object) can't be in a superposition (that's his "paradox"), the thought experiment can be tweaked to show that _something_ isn't right in the copenhagen interpretation - thus the need for some other interpretation, e.g. the multiverse theory
'Thought experiments' are never able to prove anything, as it was not a real experiment. In fact "proving" doesn't really exist in physics, just gathering evidence and drawing connections. Proofs exist in mathematics only.
But designing a hypothetical experiment using accepted physics theory is a good way of analysing consequences of that theory and what it might mean in different scenarios.
i dont like calling it the multiverse theory, rather alternate universes because in fact these are two different things. The multiverse is just other universes outside ours that we can see, go inside of and feel, and they are all linked together in a cosmic web thus called the multiverse, alternate universes are where anything and everything is possible and there is an infinite number of possible outcomes for each situation and each outcome creates a new universe, if you think of something it exists and you have just created a universe because you thought of it therefore it now exists.
VestaGamingCo
It's true that there is two seperate things concerning "many universes", one coming from the interpretation of quantum mechanics and one related to the inflationary period of the early universe.
However, be careful: Not every universe exists in either case - it has to be allowed by the laws of quantum mechanics (and the rest of physics), which (contrary to common belief) rules out almost everything.
You misunderstood him. The many universes theory is just one possible explanation that would resolve the paradox of Schrodinger"s cat. Many universes would explain the cat, the cat does not explain many universes.
Fraulein? Fraulein? HEY FRAULEIN!!!?
We would make beautiful children :3
Jeez i just watched that
this explained the concept so much better. I took the story from the newtonian p.o.v. and couldn't understand why observation has a direct influence on outcome (such as mr. "get a transparent box"). knowing now that it's a metaphor for quantum physics makes more sense.
The strange thing about it is, that one cannot come up with an explanation of all experiments (in paricular, the bell inequality) that assumes that the radioactive isotope is _either_ decayed or not, and we just don't know: One has to assume that the isotope actually is in a superposition of the two states as opposed to us just not knowing which state it is in. Schroedinger tried to argue against this in this thought experiment, which shows that this superposition can translate onto the cat.
Who else came from Echo Ruins Death?
Just make a transparent box lol
Po Yao Cheong You can't beacuse as Quantum Mechanics say, Superposition CAN NOT be Observed.This applies to the stuff inside AND the outside.
*****
¯ \ _ ( ツ ) _/ ¯
edward6000 Beacuse that's how Quantum Mechanics work.
edward6000 Instead of asking me, google it up ;D
Po Yao Cheong In order to observb, you need light, so a transparent box is permeable to light.
The light needs to reflect from the object for us to see, when it does, it alter the quantum state inducing one of the possible states.
The point of having a box, is that the quatum event is isolated, so ONLY when you open it up, you interact with the event colapsing the quantum state.
I don't know if it was intentional, but I love the fact that the segment called 'I Don't Think It Means What You Think It Means' then goes on to describe something that is largely 'INCONCEIVABLE!"
Which makes me think the cat could also be "Mostly Dead" as well... :-)
The tree question is more about the question of identity, specifically about the definition of sound.
We know that if a tree falls in the woods, no matter what it's going to create pressure waves in the air. But do we define sound as pressure waves travelling through a medium? Or do we define sound as pressure waves interacting with an observer's ears? Or what if there was a deaf person around? Does sound require a response from the brain?
No superposition here. Just definitions.
I am new to your channel and have no idea if you have already done it, but as far as IDTIMWYTIM goes, my big pet peeve is negative reinforcement. People almost always assume that it refers to, what in fact is positive punishment. It is very difficult for people to grasp the concepts of positive and negative reinforcement and how they differentiate from positive and negative punishment. I think this would be a great topic for discussion if you have someone on staff that is enough of a psych nerd (like me) to keep them straight.
They already used this cat experiment in anime. The anime is called hellsing. (In both forms, I believe). I love it btw!
and steins;gate focus everything about time and space
The idea of a superposition is based off of probabilities. When you solve quantum equations, you get multiple possible answers for the states that particles can exist in at any given moment, with a probability given to each state. But we don't know which state they exist in until we observe them.
So the idea of this experiment is, until we observe the cat, we can't know for sure which state it's in (alive or dead). We just know that it has a 50/50 chance of each. Once we open the box (cont'd)
requesting a video on the new findings in the journal nature about knowing what the cat will do ahead of time
the fact that quantum physics work differently and randomly compared to regular physics is the point this video was trying to make. you are looking at it from the point of view i was until i actually read more about it.
The discusion is whether the geiger counter is an "observer" or not. If it is an observer, it collapses the wavefunction. That's how you know it's an observer in CHI. If it is not, the geigercounter becomes entangled with the atom, and indeed it is hard to maintain entangled states, because it is hard to not meassure them. What I said is that, contrary to what was previously thought, macroscopic objects _can_ be entangled, and thus, it is not obvious that the geiger counter would be an observer.
Thankyou. This concept never madesense to me before you explained it!
Most explanations of this completely ignore most of the stuff after 2:08, this way makes so much more sense.
I might be wrong but it seems like you cannot know the position and speed of a particle such as an electron or photon because the TOOLS that we currently have: If we try to measure the precise position A at time B we will alter its velocity C; and if we determine its velocity C then we cannot know it's position A because it would have to stop moving which means it would no longer have velocity.
Thank you so much for that. I always wondered what the point of the thought experiment was. You put it in a way that I could easily understand.
superposition is the possibility of all outcomes being possible, but in the act of observation, only one outcome is viewed.
My subscription to scishow brought me here....around a year ago.
Fantastic explanation
This whole thought experiment is somewhat akin to the saying, "if a tree falls in the forest with no one around to hear it, does it make a sound?"
Please do an IDTIMWYTIM about the difference between and relationships of fact, hypothesis, law, and theory. So many people treat 'theory' as 'guess' and it makes the tiny, little bespectacled Hulk in my brain smash things
Could you do one of these segments on the atom? A lot of people have only ever seen the Bohr's diagram of an atom, which isn't completely accurate.
Schrodinger was basically repeating back to Einstein an idea Einstein had previously told him in a letter. Given than Einstein responded by saying how brilliant it was, I don't think Einstein remembered coming up with the idea in the first place. However, the point that each had made with their versions of what is now called Schrodinger's Cat, was that the idea that the wave function collapses when you observe the results of the experiment makes little sense. This is similar to what you said, but it was more specific than just that Quantum Mechanics is weird and doesn't play well with classical physics, it was an argument against a particular view in the then-hotly debated interpretations of Quantum Mechanics.
Incidentally, the Many World's view, while attractive in its simplicity, has difficulty creating a coherent theory to account for the different probabilities associate with different outcomes of quantum experiments. It seems to require not only an infinite number of universes, but a high order infinity, since sometimes you have a probability of one universe or another that isn't even a rational number.
Really great explanation.
The reason we don't count them as observers in this situation is we're defining the system inside the box, thus making us the external observers. The cat obviously observes the reaction. But until we open the box and observe the state of the cat, we have no way of knowing what state the system is in.
What this proves maybe that what you observe appears relative to what you use to measure it and where that thing(person) and or tool seem located in spacetime.
Great show!!! Gonna be watching a lot more of this
In this example, there is 50:50 change of decay/death in one hour. How about if you look only after 1/2 hour? Keeping with the analogy, the cat was in a superposition with probability 75:25 .
No problem, I'm glad to share :). With regards to the dark energy stuff, there isn't all that much to learn: We genuinly don't know how it works, or where it comes from - it just turns that if we stick an arbitrary energy into the basic equations (of general relativity), the equations match the observed facts.
Ofcourse, various people have suggested ideas on it, but to my knowledge, no one theory has been accepted as yet.
yeah right, I am now deeply in thought about what I was thinking before you thought this one out.
I love you videos because it gives people knowledge and we all know that "There is only one good, knowledge, and only one evil, ignorance". And I hate to correct you on one thing, and this is an extremely common mistake you can find all over the internet and in all kinds of English literature. This brilliant man's name is Erwin Schrödinger, not Schrodinger. If you are unable to write an "ö" for whatever reason, the correct way would be to write an "oe" instead of the "ö" but an "o" is simply wrong. Btw. the same works for "ä" and "ü".
Anyway... great work, as usual. Keep it up!
I feel as if it would be beneficial to do a brief video describing the inherent differences between a hypothesis and a theory. I feel as if there is a large misconception between the two as people are often more likely to use the term "theory" when describing what is most certainly a hypothesis. As an undergrad my professors made it a point to emphasis the fundamental differences between the two since they obviously recognized the prevalence of this misconception.
Please disregard this comment if you have already made a video concerning the nature if my suggestion and thank you for your insight as always.
The many worlds interpretation meshes quite nicely with alternate, "what if" history and provides real-life settings for alternate scenarios to take place - just not in this particular universe!
According to most sources I have read, Schrodinger's goal with the cat thought experiment was actually to disprove quantum physics, by showing the absurdity of the outcome. Along with a few of his contemporaries, after helping discover and develop quantum physics, he spent the rest of his life trying to disprove it. The fact that this thought experiment is now used to teach quantum physics is a bit of irony.
The point is precisely that the particles _wouldn't_ reverse trajectories, they would continue to behave as we are used to. This (more or less) implies that entropy will keep rising.
The reason why it is no longer relevant is (as far as I understand) that the discovery of the acceleration of the expansion of the universe "negates" the mechanism that would have led to big crunch.
That's beside the point. Were we talking about about three states of being instead of two, it would be a 33% chance instead of 50%, but that would be a different problem altogether. The experiment is completely untestable in its described form, but that doesn't make it any less valuable as a model to illustrate the concept. Look at all the folks who have posted things like "now it makes sense". That's the point.
It's the 50/50 probability that's important, not what you use to describe it.
Very good explanation
Wish I had found this channel sooner!
When i explain it i use the cat as having the superposition because most people would understand it better that way. Also, the shock value gets me my jollies.
After reading some of Dan Simmons' work I can't help but agree with you on the plot device part x) It's pretty awesome
As the years go by our cameras get better and better and yet youtubers get closer and closer.
Because in the double slith experiment photons influenced the behaviour of quantum particles, so it made sense to take those out of the mental experiment.
Still, when the counter mesure the decay, the superposition (aka the random variable, for the matematicians) collapse into a precise state, namely a realization of the random variable (also for the matematicians), so you don't need to open the box at all, the setup of the experiment does the observation for you...