Schrödinger’s Kittens - The Boundary Between Quantum And Classical Mechanics
Schrödinger’s cat is a famous thought experiment in Physics. It goes as follows.
A cat, flask of poison and radioactive source are put in a box. If the monitor in the box (Geiger counter) detects radioactive decay, a hammer falls on the flask, the poison is released and the cat is killed.
Since there is a 50/50 chance of decay occurring; logic tells us there is a 50/50 chance of the cat surviving. There is a 50% chance of the cat being dead and a 50% chance of it being alive and it is either dead or alive.
Quantum mechanics however tells us that very small particles exist in a state of quantum superposition. This means that properties such as there exact location are undetermined until we measure them. Before measurement there is only a probability of the properties they can have. Does this mean that the cat exists in a superposition of being simultaneously dead and alive and only upon opening the box does this collapse into one state of being dead or alive?
The cat thought experiment was used by Schrödinger to show what he saw as a problem in quantum mechanics when it is scaled up to larger sizes. He wanted to show that we can't think of a cat as both dead and alive and so the interpretation of quantum mechanics is wrong. Einstein agreed with Schrödinger as he was a critic of quantum mechanics. He thought it was crazy that reality depended on our observations to determine its properties. He also thought the dependence on probability was just Physicists not understanding the laws of Physics correctly and famously wrote "God does not play dice".
The standard interpretation of quantum mechanics however does suggest probabilities are involved and observations do affect a particles properties.
So if it seems absurd that Schrödinger’s cat exists in a state of superposition, how big do things get before quantum properties start to disappear and we see the quantum-classical transition that is highlighted by Schrödinger’s thought experiment.
Latest experimental results show that Schrödinger’s Kittens (objects between the atomic scale and the size of the cat) can be put in quantum states where you can't definitely say which properties the system has until they are observed. Things the same size as bacteria and viruses have been able to be put in these states which asks the question: How big can things get while still preserving quantum properties. Physicists are continuing to work their way up and attempt to put larger and larger objects in superposition. As objects get bigger we may be able to also see how gravity effects quantum behavior. This could then offer hints in how to develop a theory of everything (quantum gravity) which unites the incompatible theories of quantum mechanics an general relativity.
To read the full article on this topic click the link below
https://www.quantamagazine.org/real-life-schrodingers-cats-probe-the-boundary-of-the-quantum-world-20180625/
Thanks for reading. If you enjoyed this post or any of my others, follow and subscribe to my blog. Feel free to discuss anything related to this post in the comments below.
A cat, flask of poison and radioactive source are put in a box. If the monitor in the box (Geiger counter) detects radioactive decay, a hammer falls on the flask, the poison is released and the cat is killed.
Since there is a 50/50 chance of decay occurring; logic tells us there is a 50/50 chance of the cat surviving. There is a 50% chance of the cat being dead and a 50% chance of it being alive and it is either dead or alive.
Quantum mechanics however tells us that very small particles exist in a state of quantum superposition. This means that properties such as there exact location are undetermined until we measure them. Before measurement there is only a probability of the properties they can have. Does this mean that the cat exists in a superposition of being simultaneously dead and alive and only upon opening the box does this collapse into one state of being dead or alive?
The cat thought experiment was used by Schrödinger to show what he saw as a problem in quantum mechanics when it is scaled up to larger sizes. He wanted to show that we can't think of a cat as both dead and alive and so the interpretation of quantum mechanics is wrong. Einstein agreed with Schrödinger as he was a critic of quantum mechanics. He thought it was crazy that reality depended on our observations to determine its properties. He also thought the dependence on probability was just Physicists not understanding the laws of Physics correctly and famously wrote "God does not play dice".
The standard interpretation of quantum mechanics however does suggest probabilities are involved and observations do affect a particles properties.
So if it seems absurd that Schrödinger’s cat exists in a state of superposition, how big do things get before quantum properties start to disappear and we see the quantum-classical transition that is highlighted by Schrödinger’s thought experiment.
Latest experimental results show that Schrödinger’s Kittens (objects between the atomic scale and the size of the cat) can be put in quantum states where you can't definitely say which properties the system has until they are observed. Things the same size as bacteria and viruses have been able to be put in these states which asks the question: How big can things get while still preserving quantum properties. Physicists are continuing to work their way up and attempt to put larger and larger objects in superposition. As objects get bigger we may be able to also see how gravity effects quantum behavior. This could then offer hints in how to develop a theory of everything (quantum gravity) which unites the incompatible theories of quantum mechanics an general relativity.
To read the full article on this topic click the link below
https://www.quantamagazine.org/real-life-schrodingers-cats-probe-the-boundary-of-the-quantum-world-20180625/
Thanks for reading. If you enjoyed this post or any of my others, follow and subscribe to my blog. Feel free to discuss anything related to this post in the comments below.
Cool blog! Have you ever read about entanglements?
ReplyDeleteI've watched a couple of videos giving brief explanations but I haven't done anything in depth yet. I hope to in the future though!
DeleteThis book will explain it all as well as giving future uses for entanglements .
DeleteAlsoo the part about observations affecting a particles properties, do you mean for example, electrons not having positions until you measure them? Or are you talking about what Heisenberg originally thought was uncertainty in that by observing a system you disturb it? Or am I just being dumb and you are talking about something completely different?
ReplyDeleteYes I'm referring to electrons having a probability of possible positions until measurement.
DeleteWould highly recommend Quantum Chance by Nicolas Gisin it's to do with this kind of stuff
ReplyDeleteThanks does that book include some of the maths in quantum mechanics? Or is it just explanations from a purely conceptual point of view?
DeleteIt includes some maths but it's quite simple. It has the bell inequality which is really interesting but again simple it's basically an inequality that must be obeyed if nature is local but then you learn about these nonlocal correlations made possible by entanglements and quantum indeterminacy its all explained really well in the book.
DeleteI guess there is no real explanation for entanglements that we know of so there isn't any maths when it comes to explaining that. It's more theoretical. They do have a no cloning theory by which it is impossible to produce a quantum clone which cool.
DeleteAlright thanks! I'll definitely take a look at it in the future and do a review on it.
DeleteYES, I look forward to reading your review!
Delete