What are the examples of thought experiments?

Question

I read about the gedanken experiments recently. in context to the one 'carried out' by Heisenberg while putting forward the uncertainty principle. Where can i find more information on these?

Answer 1

Famous thought experiments

Brownian ratchet (Richard Feynman's "perpetual motion" machine which does not violate the second law, and does not work)
Casimir cones (Basis for almost perpetual motion machine fueled by entropy)[1]
Galileo's ship (classical relativity principle) 1632
GHZ experiment (quantum mechanics)
EPR paradox (quantum mechanics) (forms of this have actually been performed)
Maxwell's demon (thermodynamics) 1871
Quantum suicide (quantum mechanics)
Schrödinger's cat (quantum mechanics)
Twin paradox (special relativity)
Wigner's friend (quantum mechanics)
Wittgenstein's rod (engineering mechanics)- an exercise in visualization
Bucket argument- argues that space is absolute, not relational

Answer 2

First of all and as you undoubtedly know... Thought experiments are devices of the imagination used to investigate the nature of things. We need only list a few of the well-known thought experiments to be reminded of their enormous influence and importance in the sciences: Newton's bucket, Maxwell's demon, Einstein's elevator, Heisenberg's gamma-ray microscope, Schrödinger's cat

As far as examples, we can cite scientists, Galileo and Einstein who were, arguably, the most impressive thought experimenters, but they were by no means the first. Thought experiments existed throughout the middle ages, and can be found in antiquity, too. One of the most beautiful early examples (in Lucretius, De Rerum Natura) attempts to show that space is infinite: If there is a purported boundary to the universe, we can toss a spear at it. If the spear flies through, it isn't a boundary after all; if the spear bounces back, then there must be something beyond the supposed edge of space, a cosmic wall that stopped the spear, a wall that is itself in space. Either way, there is no edge of the universe; space is infinite.

This example nicely illustrates many of the common features of thought experiments: We visualize some situation; we carry out an operation; we see what happens. It also illustrates their fallibility. In this case we've learned how to conceptualize space so that it is both finite and unbounded. Consider a circle, which is a one dimensional space: As we move around, there is no edge, but it is nevertheless finite. The universe might be a many-dimensional version

Answer 3

Here is an example:

People used to think that heavy objects fell faster than light objects. Galileo reasoned that this can not be the case through a thought experiment. Think of a light stone and a heavy stone connected by a rope and let them free fall from the top of the Pisa tower. Now if the assumption wis right the heavy stone will fall faster and the light one will fall slower. Because they are connected by a rope, the light one will be slowing the heavy one, and both of them together would be falling at a speed which is slightly less then what would be the speed of the heavy stone if it was falling alone.

But on the other hand because the light stone and the heavy stone together form an object heavier than the heavy stone itself, together they must be falling faster than what would be the speed of the heavy stone if it was falling alone. These two situations can not occur at the same time. So our assumption that heavier objects should fall faster must be wrong

Answer 4

An example of such an experiment is Maxwell's Demon. In this experiment, Clerk Maxwell. The following is from The Human Use of Human Beings by Norbert Weiner:

"Suppose that we have a container of gas, whose temperature is everywhere the same. Some molecules of this gas will moving faster than others. Now let us suppose that there is a little door in the container that lets the gas into the tube which runs to a heat engine, and that the exhaust of this heat engine is connected byh another tube back to ghe gas chamber, through another door. At each door there is a little being with the power of watching the on-coming molecules and of opening or closing the doors in accordance with their velocity.

"The demon at the first door opens it only for high speed molecules and closes it in the face of low speed molecules coming from the other container. The role of the demon at the second door is exacetly the opposite. . . The result is that the temperature goes up at one end and down at the other thus creating a perpetual motion of the 'second kind': that is, a perpetual mothion which does not violate the first law of thermodynamics, which tells us that them amount of energy within a given system is constant, but does violate the second law of thermodynamics, which tells us that energy spontaneously runs down hill in tempertaure. In other words, the Maxwell demon seems to overcome the tendence of entropy to increase."

Answer 5

i'm guessing your "parables" stem from the economic cliff and no count if or no longer we ought to consistently boost the tax cuts for the wealthy. Your argument is that some human beings are biologically smarter than others and by this the traditional human beings with person-friendly to diminish IQ won't in any respect ever be smarter than the folk who've "clever". mutually as your bench pressing analogy is extremely relaxing you circulate away out the certainty that maximum people who bench press generally decide for different people who're liable to get greater suitable. i think of we call them well being fanatics. those reliable individuals decide for to help individuals get greater suitable even nonetheless our genes exhibit that the weaker guy won't in any respect grow to be as reliable because of the fact the biologically muscular guy. whether you experience that in view that human beings would be wealthy and a few human beings would be unfavorable that the wealthy shouldn"t help the less fortunate out by utilising paying taxes. this means that your thoughts do no longer line up fairly properly alongside with your center arument. lots of the wealthy do no longer decide for to pay greater taxes even nonetheless which will earnings the "proles".

Answer 6

Hi. An experiment that is reasoned out rather than tested. Einstein used them for explanation to laymen (laypersons?). Try Schrödinger's Cat.

Answer 7

Try not to think of an elephant.

Oh, I loved Schroinger's Cat!

Actually, more massive objects do fall faster, because they have more mass and exert more gravity. Galileo was wrong.

Answer 8

http://en.wikipedia.org/wiki/Gedanken