# The life and death of Schrodinger's cat, and what it really means

Schrodinger's cat is one of the most famous thought experiments of all time, but what does it mean for science, and what happens to the poor cat?

Schrodinger's cat is one of the most famous thought experiments in all of science. It's the source of countless jokes, t-shirts, and pseudo-intellectual conversations. The idea is this: if a cat is put into a box with an elaborate quantum booby trap then when we open the box the trap will either be activated and kill the cat or not be activated at all. Quantum Physics says the cat should be in “**superposition**" while we are not looking at it, just like the rest of the quantum system. **Meaning the cat is both alive and dead at the same time until we look at it!** Zombie cat!

**Incredible! Except, Schrodinger didn't mean that at all.**

Erwin Schrodinger, quantum physicist extraordinaire, devised the thought experiment as a way to show how the Copenhagen Interpretation of quantum mechanics, the mainstream one, must be wrong. Pointing out that we cannot think of a cat as both alive and dead at the same time, but if the interpretation tells us this is the case, then it must be incorrect.

Albert Einstein, who was never completely comfortable with much of quantum mechanics, also agreed, writing to Erwin: **“You are the only contemporary physicist, besides Laue, who sees that one cannot get around the assumption of reality, if only one is honest. Most of them simply do not see what sort of risky game they are playing with reality—reality as something independent of what is experimentally established. Their interpretation is, however, refuted most elegantly by your system of radioactive atom + amplifier + charge of gunpowder + cat in a box, in which the psi-function of the system contains both the cat alive and blown to bits. Nobody really doubts that the presence or absence of the cat is something independent of the act of observation."**

Schrodinger later tried for a purely wave based understanding of quantum mechanics, but it was never as popular nor successful as the Copenhagen understanding, which is still dominant today. Of course, there are other ways to look at it, here are a few, and what happens to the poor cat in each one. There are many more interpretations than just these, but these are the most popular alternatives.

A happy cat, not in quantum superposition or a box with a trap in it.

**MANY WORLDS**: The idea of the multiverse is known to many people. In this interpretation, the cat is alive in one universe and dead in another one. The new universe was “created" when the cat is observed, there is no being alive and dead for this cat. This model of the universe is seen in *Bioshock Infinite*, and *Rick and Morty;* among other popular works.

**OBJECTIVE COLLAPSE**: These theories suggest that the system would collapse long before you open the box, either with the passage of enough time or some other simple event. Therefore, the cat is in a definite state of alive or dead long before you look. This does, however, leave open the idea that the cat is both for at least a fraction of a moment, it just doesn't stay that way long.

**All this is great in theory, has anybody tried an experiment?**

Yes, but not on a cat. Objects that are rather large, for these purposes, have been placed in superposition. These states don't seem to last long, however. We aren't even to the point of having bacteria be in a “cat state" yet. It seems like no experiment has been done, or will be done for some time.

Schrodinger's cat is one of the best known thought experiments in science. One that most people know, but few understand. While it was intended to be a simple critique, it has evolved into a key test for judging how an understanding of quantum mechanics works, and if that interpretation is a viable one. Is the cat alive? Is it dead? Is it both? How can we know? How is this possible? A quote from Richard Feynman comes to mind:

**“Do not keep saying to yourself, if you can possibly avoid it, "But how can it be like that?" because you will get "down the drain", into a blind alley from which nobody has yet escaped. Nobody knows how it can be like that."**

This is still a subject of great debate, both for physics and philosophy. Perhaps a new interpretation will be proposed which finally lays the cat to rest, or lets it live outside of the box, or both.

## Why the number 137 is one of the greatest mysteries in physics

Famous physicists like Richard Feynman think 137 holds the answers to the Universe.

- The
**fine structure constant**has mystified scientists since the 1800s. - The number
**1/137**might hold the clues to the Grand Unified Theory. - Relativity, electromagnetism and quantum mechanics are unified by the number.

## Americans under 40 want major reforms, expanded Supreme Court

Younger Americans support expanding the Supreme Court and serious political reforms, says new poll.

- Americans under 40 largely favor major political reforms, finds a new survey.
- The poll revealed that most would want to expand the Supreme Court, impose terms limits, and make it easier to vote.
- Millennials are more liberal and reform-centered than Generation Z.

## Can you solve what an MIT professor once called 'the hardest logic puzzle ever'?

Logic puzzles can teach reasoning in a fun way that doesn't feel like work.

- Logician Raymond Smullyan devised tons of logic puzzles, but one was declared by another philosopher to be the hardest of all time.
- The problem, also known as the Three Gods Problem, is solvable, even if it doesn't seem to be.
- It depends on using complex questions to assure that any answer given is useful.

### The Three Gods Problem

<iframe width="730" height="430" src="https://www.youtube.com/embed/UyOGZk7WbIk" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe><p> One of the more popular wordings of the problem is:<br> <br> "Three gods A, B, and C are called, in no particular order, True, False, and Random. True always speaks truly, False always speaks falsely, but whether Random speaks truly or falsely is a completely random matter. Your task is to determine the identities of A, B, and C by asking three yes-no questions; each question must be put to exactly one god. The gods understand English, but will answer all questions in their own language, in which the words for <em>yes</em> and <em>no</em> are <em>da</em> and <em>ja</em>, in some order. You do not know which word means which."<br> <br> Boolos adds that you are allowed to ask a particular god more than one question and that Random switches between answering as if they are a truth-teller or a liar, not merely between answering "da" and "ja." <br> <br> Give yourself a minute to ponder this; we'll look at a few answers below. Ready? Okay. <strong><br> <br> </strong>George Boolos' <a href="https://www.pdcnet.org/8525737F00588A37/file/31B21D0580E8B125852577CA0060ABC9/$FILE/harvardreview_1996_0006_0001_0060_0063.pdf" target="_blank" rel="noopener noreferrer">solution</a> focuses on finding either True or False through complex questions. </p><p> In logic, there is a commonly used function often written as "iff," which means "if, and only if." It would be used to say something like "The sky is blue if and only if Des Moines is in Iowa." It is a powerful tool, as it gives a true statement only when both of its components are true or both are false. If one is true and the other is false, you have a false statement. </p><p> So, if you make a statement such as "the moon is made of Gorgonzola if, and only if, Rome is in Russia," then you have made a true statement, as both parts of it are false. The statement "The moon has no air if, and only if, Rome is in Italy," is also true, as both parts of it are true. However, "The moon is made of Gorgonzola if, and only if, Albany is the capitol of New York," is false, because one of the parts of that statement is true, and the other part is not (The fact that these items don't rely on each other is immaterial for now).</p><p> In this puzzle, iff can be used here to control for the unknown value of "da" and "ja." As the answers we get can be compared with what we know they would be if the parts of our question are all true, all false, or if they differ. </p><p> Boolos would have us begin by asking god A, "Does "da" mean yes if and only if you are True if and only if B is Random?" No matter what A says, the answer you get is extremely useful. As he explains: <br> </p><p> "If A is True or False and you get the answer da, then as we have seen, B is Random, and therefore C is either True or False; but if A is True or False and you get the answer ja, then B is not Random, therefore B is either True or False… if A is Random and you get the answer da, C is not Random (neither is B, but that's irrelevant), and therefore C is either True or False; and if A is Random...and you get the answer ja, B is not random (neither is C, irrelevantly), and therefore B is either True or False."<br> <br> No matter which god A is, an answer of "da" assures that C isn't Random, and a response of "ja" means the same for B. </p><p> From here, it is a simple matter of asking whichever one you know isn't Random questions to determine if they are telling the truth, and then one on who the last god is. Boolos suggests starting with "Does da mean yes if, and only if, Rome is in Italy?" Since one part of this is accurate, we know that True will say "da," and False will say "ja," if faced with this question. </p><p> After that, you can ask the same god something like, "Does da mean yes if, and only if, A is Random?" and know exactly who is who by how they answer and the process of elimination. </p><p> If you're confused about how this works, try going over it again slowly. Remember that the essential parts are knowing what the answer will be if two positives or two negatives always come out as a positive and that two of the gods can be relied on to act consistently. </p><p> Smullyan wrote several books with other logic puzzles in them. If you liked this one and would like to learn more about the philosophical issues they investigate, or perhaps if you'd like to try a few that are a little easier to solve, you should consider reading them. A few of his puzzles can be found with explanations in this <a href="https://www.nytimes.com/interactive/2017/02/11/obituaries/smullyan-logic-puzzles.html" target="_blank" rel="noopener noreferrer">interactive</a>. </p>## New tardigrade species withstands lethal UV radiation thanks to fluorescent 'shield'

Another amazing tardigrade survival skill is discovered.