• The forum upgrades are now largely complete.
    Please read this thread for more details.
    New user registrations are currently disabled.

UFO's

It can't. Again, that's a classic pseudo-scientific misrepresentation. Stop telling people that. It's wrong.
In this interpretation of quantum mechanics the status of the cat is unknown so you can think of the distinct probabilities of it being alive and dead as simultaneously existing.

When you observe (open the box) the probabilities (or the wave function in QM) collapses to an eigenstate (the cat is observed to be dead OR alive but never both)
 

It can't. Again, that's a classic pseudo-scientific misrepresentation. Stop telling people that. It's wrong.

Can you explain why he's wrong?

As far as I can tell, his description seems completely in line with the idea of superposition described by the thought experiment, and by a number of the most prevalent interpretations, such as the Copenhagen Interpretation.

There are some interpretations that reject the idea of superposition, but they're by no means the most popular interpretations.
 
In this interpretation of quantum mechanics the status of the cat is unknown so you can think of the distinct probabilities of it being alive and dead as simultaneously existing.

When you observe (open the box) the probabilities (or the wave function in QM) collapses to an eigenstate (the cat is observed to be dead OR alive but never both)
You're confusing our models of reality with actual reality. They are not the same thing. It's like saying a calendar and the passage of time are the same thing. You can use a calendar (model) to describe time, but it doesn't represent an accurate description of reality.

The mistake people often make is when they try to visualise abstract mathematical models. You can't. Nobody can. You'll always get it wrong. You'll come away with completely wrong ideas. The only way to understand it is by using mathematics.
Can you explain why he's wrong?
He's attempting to describe an abstract mathematical model using words and visualisations. It's impossible. Nobody can. Any attempt to will lead to confusion and misleading conclusions.

I couldn't explain it without using maths, and tbh, I lack the expertise to do it properly. It's incredibly hard.
 
Last edited:
The mistake people often make is when they try to visualise abstract mathematical models. You can't. Nobody can.

Which was my whole point.

We can't imagine that a cat is both dead AND alive at the same time, your (our) puny minds can't really imagine that, by imagine I mean picture it in your minds eye, it doesn't make sense to us.

I hear many people say "that can't be true, it doesn't make any sense" and what I'm trying to say is that doesn't really stand up because there are lots of things that "don't make sense" but are true anyway
 
Watch Susskind's "little sermon" from 5:27. It's only a few minutes long, but repeats what I've said above in more detail.

You must be logged on to see media items

Right, OK, so it's not so much that you're criticising the other poster's description of the Schrodinger's Cat thought experiment (which he did correctly), it's that you're criticising the Schrodinger's Cat thought experiment itself for being an inaccurate description of quantum mechanics (even though it's only an analogy, clearly hypothetical, and has been adopted by the scientific community as a good starting block from which it becomes easier to visualise the differences in the various interpretations of quantum mechanics).

Fair enough.

I disagree, but at least now I can see where you're coming from.

Interesting video by the way. I like Susskind. I found it interesting that when he's talking about the apparatus, the questions from the audience seem to be from people who seem to really struggle to follow what he's saying (the part of the video I found the most straightforward) but then when he moved onto the maths stuff, they were all absolutely fine with everything he was saying (the part of the video I was struggling to follow).

It was as if halfway through the video they swapped out the original audience of small town gas station attendants and street sweepers, and replaced them with a crowd of seasoned mathematicians. :D
 
Last edited:
So what’s at the border of something and nothing ? We have “space” then just no colour ? A invisible wall?
We have the sky and the then the Firmament, We live in a pressurised sealed realm with a flat earth the those who don't believe this are victims of years of conditioning by the media
 
So what’s at the border of something and nothing ? We have “space” then just no colour ? A invisible wall?
Nothing isn't an "it".

I like the description on Space.com....

"To answer the question of what's outside the universe, we first need to define exactly what we mean by "universe." If you take it to mean literally all the things that could possibly exist in all of space and time, then there can't be anything outside the universe. Even if you imagine the universe to have some finite size, and you imagine something outside that volume, then whatever is outside also has to be included in the universe.

Even if the universe is a formless, shapeless, nameless void of absolutely nothing, that's still a thing and is counted on the list of "all the things" — and, hence, is, by definition, a part of the universe.

...

When you imagine the universe, you might think of a giant ball that's filled with stars, galaxies and all sorts of interesting astrophysical objects. You may imagine how it looks from the outside, like an astronaut views Earth from a serene orbit above.

But the universe doesn't need that outside perspective in order to exist. The universe simply is. It is entirely mathematically self-consistent to define a three-dimensional universe without requiring an outside to that universe. When you imagine the universe as a ball floating in the middle of nothing, you're playing a mental trick on yourself that the mathematics does not require.

Granted, it sounds impossible for there to be a finite universe that has nothing outside it. And not even "nothing" in the sense of an empty void — completely and totally mathematically undefined. In fact, asking "What's outside the universe?" is like asking "What sound does the color purple make?" It's a nonsense question, because you're trying to combine two unrelated concepts.

It could very well be that our universe does indeed have an "outside." But again, this doesn't have to be the case. There's nothing in mathematics that describes the universe that demands an outside."


 
I like the description on Space.com....

"To answer the question of what's outside the universe, we first need to define exactly what we mean by "universe." If you take it to mean literally all the things that could possibly exist in all of space and time, then there can't be anything outside the universe. Even if you imagine the universe to have some finite size, and you imagine something outside that volume, then whatever is outside also has to be included in the universe.

Even if the universe is a formless, shapeless, nameless void of absolutely nothing, that's still a thing and is counted on the list of "all the things" — and, hence, is, by definition, a part of the universe.

...

When you imagine the universe, you might think of a giant ball that's filled with stars, galaxies and all sorts of interesting astrophysical objects. You may imagine how it looks from the outside, like an astronaut views Earth from a serene orbit above.

But the universe doesn't need that outside perspective in order to exist. The universe simply is. It is entirely mathematically self-consistent to define a three-dimensional universe without requiring an outside to that universe. When you imagine the universe as a ball floating in the middle of nothing, you're playing a mental trick on yourself that the mathematics does not require.

Granted, it sounds impossible for there to be a finite universe that has nothing outside it. And not even "nothing" in the sense of an empty void — completely and totally mathematically undefined. In fact, asking "What's outside the universe?" is like asking "What sound does the color purple make?" It's a nonsense question, because you're trying to combine two unrelated concepts.

It could very well be that our universe does indeed have an "outside." But again, this doesn't have to be the case. There's nothing in mathematics that describes the universe that demands an outside."



You must be logged on to see media items
 
He used to be a bit prickly but in the last couple of years he has become an aggressive bully and I no longer watch it.

Yeah, I went through a phase of watching it a few years back but tailed off after a while.

Too much mute button, threats of cutoffs and actual cutoffs.

No need, IMO. He has logic on his side.
 
Right, OK, so it's not so much that you're criticising the other poster's description of the Schrodinger's Cat thought experiment (which he did correctly), it's that you're criticising the Schrodinger's Cat thought experiment itself for being an inaccurate description of quantum mechanics (even though it's only an analogy, clearly hypothetical, and has been adopted by the scientific community as a good starting block from which it becomes easier to visualise the differences in the various interpretations of quantum mechanics).

Fair enough.

I disagree, but at least now I can see where you're coming from.

Interesting video by the way. I like Susskind. I found it interesting that when he's talking about the apparatus, the questions from the audience seem to be from people who seem to really struggle to follow what he's saying (the part of the video I found the most straightforward) but then when he moved onto the maths stuff, they were all absolutely fine with everything he was saying (the part of the video I was struggling to follow).

It was as if halfway through the video they swapped out the original audience of small town gas station attendants and street sweepers, and replaced them with a crowd of seasoned mathematicians. :D
No I was disagreeing with his interpretation of the argument that Schrodinger put forward. It often gets stated, usually by respected physicists, that "the cat is both alive and dead at the same time", and it's completely wrong. It's a terrible attempt by the physicist to explain an abstract idea, QM, to the general public without using abstract maths, which is impossible. They unintentionally mislead people when trying to explain it, and you end up with people like the lad above telling others about a magical quasi-cat.

The "cat" Shrodinger was talking about was a particle. Not a cat. It doesn't apply to cats. A cat is a cat. It's either there or it isn't, regardless of whether or not it's in a box.

And I can't be arsed to do the umlaut's over Schrodinger's O's so you'll just have to just imagine they're there.
 
.
No I was disagreeing with his interpretation of the argument that Schrodinger put forward. It often gets stated, usually by respected physicists, that "the cat is both alive and dead at the same time", and it's completely wrong. It's a terrible attempt by the physicist to explain an abstract idea, QM, to the general public without using abstract maths, which is impossible. They unintentionally mislead people when trying to explain it, and you end up with people like the lad above telling others about a magical quasi-cat.

The "cat" Shrodinger was talking about was a particle. Not a cat. It doesn't apply to cats. A cat is a cat. It's either there or it isn't, regardless of whether or not it's in a box.

And I can't be arsed to do the umlaut's over Schrodinger's O's so you'll just have to just imagine they're there.

Schrodinger's Cat analogy was originally intended as a criticism of the Copenhagen Interpretation of quantum mechanics, which states that a quantum system remains in superposition until exposed to the outside world. The thought experiement was a reductio ad absurdum to an extent, but one that fit so well it was adopted by the scientific community.

In Schrodinger's example, the cat can be said to be both alive and dead at the same time because the cat is considered to be the quantum system of the thought experiment. As you rightly say, the cat is purely analogous to a particle in superposition, where the two states of superposition are "alive" and "dead". Until the box is opened, the wavefunction is yet to collapse. Once opened, it collapses into one state or the other. Until then, it is in both states according to Copenhagen.

Of course there's the argument that the cat can be considered an observer. The Relational Interpretation for example suggests that the cat is an observer of the internal system, whereas the experimenter is an observer of the larger system, allowing the two observers to have different information about the system. In this interpretation, the cat has already witnessed the wavefunction collapse before the box has opened, whereas to the experimenter the system remains in superposition until the box is opened.

In the Wigner's Friend thought experiment, a friend of the experimenter checks the box without telling the experimenter. In this scenario, from the perspective of the experimenter, the friend becomes a part of the wavefunction, having different information about the quantum system than the experimenter has.

There are other interpretations that deny that superposition ever happens at all, and the cat is only ever alive or dead.

There's also the often misquoted Many Worlds Interpretation that states that the universe itself splits into two separate decoherent universes, one within which the cat is alive and one within which the cat is dead.

That's the one that bugs the shit out of me when I see folks misquoting it. Entire sci-fi TV shows and movies have been created based on the concept that "every decision you make splits off another universe, and there are an infinite number of universes where everything is possible..." NO, JUST f***ing NO. :lol:
 
Last edited:
Back
Top