10 Interesting thought experiments

A list created by Lee Sonogan


“Science is not about making predictions or performing experiments. Science is about explaining.”
― Bill Gaede

A thought experiment considers some hypothesis, theory, or principle for the purpose of thinking through its consequences. Given the structure of the experiment, it may not be possible to perform it, and even if it could be performed, their need not be an intention to perform it.

List of thought experiments:

  1. Schrödinger’s cat (Quantum Superposition theory states that at a quantum level, a particle or any life form may be in an undetermined state that is sort of in-between states of existence, which collapses into a certain state only upon being observed. For example a cat in a box could be dead or alive depending on observation or opening the box.)
  2. Allegory of the cave (Some people have lived all their lives in a cave held in place by chains and facing a blank wall. They watch the shadows on the wall of things passing by the front of a fire, which is behind them. They create names for the shadows. Some of the shadows’ appear at the same time as when they get water and food. For them, the shadows are the reality. They do not even have a desire to leave the cave because they have not known any other way of life. The philosopher sees the true nature of reality, not the manufactured reality of the shadows that are thought to be the reality by those held in the cave.)
  3. Unexpected hanging paradox (In this thought experiment, a prisoner on death row is told he will be hanged one day next week between Monday and Friday and he will not know the day of the hanging in advance. This means that he cannot be hanged on Friday because if he is alive on Thursday he will know in advance of his hanging on Friday, which is the last day of the week it is possible for the hanging.)
  4. Time travel paradox (If a time machine existed that allowed a person to travel back in time and they used it to go back to kill their own grandfather, how could that person still exist? One way that quantum scientists used to explain how to avoid the time travel paradox is by using an infinite number of multiple universes. Gong back in time and killing your own grandfather would only kill him in a parallel universe that is identical to the one you come from, with the sole exception that there is no grandfather and therefore no you in it.)
  5. Brain in a jar (If a computer was sophisticated enough to both provide stimulus to the brain in the jar and react to the brain’s activity in the same ways as if it was still inside the skull of a living human being, then the brain, from its perspective, would not be able to tell that it was in a jar and would have experiences that to the brain seem exactly like reality. Or would it?
  6. The Infinite Monkey Theorem (If you had an infinite amount of monkeys that were trained to type on a keyboard, given an infinite length of time, eventually, one of them would type a Shakespeare play by typing at random. In fact, one would type all of Shakespeare’s work. Moreover, many would type copies of any finite work like a Shakespeare play an infinite number of times. Even though the probability of a monkey typing Shakespeare is extremely low, it is not zero. There is mathematical proof of this theorem.)
  7. Are you real or a copy of yourself? (Over a period of approximately seven years’ time, every cell in the human body has been replaced by a new one serving the same function as the previous one. If every cell in your body is different, are you still the same person? A different examples is there was a ship from Theseus. Over many years of use, parts of the ship began to wear out. The people of Athens kept the ship in good repair. As each part wore out, it was replaced by a new part. Over time, all the parts of the ship had been completely replaced. Is this still the ship from Theseus?)
  8. The Experience machine (Suppose there were an experience machine that would give you any experience you desired. Neuropsychologists could stimulate your brain so that you would think and feel you were writing a great novel, or making a friend, or reading an interesting book. All the time you would be floating in a tank, with electrodes attached to your brain. Should you plug into this machine for life, preprogramming your life experiences? While in the tank you won’t know that you’re there; you’ll think that it’s all actually happening. Would you plug in?)
  9. Kavka’s Toxin Puzzle (In Kavka’s Toxin Puzzle, you’re approached by a billionaire with a bottle of poison. Apart from giving you intense pain for an entire day, the poison won’t cause any lasting effects if you drink it. Afterward you’ll be totally fine.The billionaire says that if you can intend at the end of the day to drink the poison the following afternoon, he’ll give you $1 million. The money will be in your bank account in the morning, before the time you meant to drink the poison, at which point you can decide not to, and he won’t ask for the money back. It seems simple, but knowing that you could back out after the fact, Kavka suggests that it is impossible for anyone to truly intend to drink the poison.
  10. Buridan’s ass (A donkey finds itself placed precisely between two equally tempting piles of hay. There is absolutely no difference between either of the potential dinners. What will the donkey do? The hungrier it gets, the more it desires to eat and the more important its choice becomes. If neither pile has an advantage over the other, then how can the donkey pick one? It will continue pondering the choice until it dies.)

“The logic of the symbol does not express the experiment; it is the experiment. Language is the phenomenon, and the observation of the phenomenon changes its nature.”
― Carlos Fuentes, Christopher Unborn

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