Throwing a tennis ball through a wall

[ZapperZ]

Yes, but then we go back to the fact that many very very smart people specialized in the subject have written books about the possibility. Books that are used to teach graduate level classes on Quantum Mechanics.

Where in a graduate level QM text does it tell you that a tennis ball call tunnel through a wall?

Zz.

 

[Greenman]

In Takagi's book. He describes how cohesive environments can be achieved and maintained and how macroscopic tunneling can occur in these environments.He actually uses a tennis ball and a wall as an example.

 

[ZapperZ]

In Takagi's book. He describes how cohesive environments can be achieved and maintained and how macroscopic tunneling can occur in these environments.He actually uses a tennis ball and a wall as an example.

And he has how much experimental evidence for this?

Look, I've given you examples of the Higgs, and the Delft/Stony Brook experiments. Especially in the Delft/Stony Brook experiments, they are doing nothing more than "textbook physics". Yet, these are still important experiments to show that, yes, a "macroscopic particle" CAN exhibit quantum properties. All they are doing is show how Leggett's scheme can, in fact, work! It was THE experimental verification. We didn't just sit back and applaud Leggett's cleverness at making such logical derivation out of what is essentially textbook physics!

You've jumped way past that already in your devotion to Takagi's book! This doesn't worry you at all? Forget about tunneling through a wall. Did you ever insisted to be shown this experimental evidence of a tennis ball being in such a coherent state FIRST? If there is one, please give me such a reference. Till then, I'm done with this discussion.

Zz.

 

[imiyakawa]

You can measure very accurately the position of the ball and its momentum simultaneously, and follow the trajectory of the ball every single step of the way. These are physical behavior that you cannot do with a quantum object.

According to professor Brian Greene, you can't. People just think they can because for all practical purposes a macroscopic measurement appears accurate, but it never really is.

 

[ArjenDijksman]

In Takagi's book. He describes how cohesive environments can be achieved and maintained and how macroscopic tunneling can occur in these environments.He actually uses a tennis ball and a wall as an example.

Maybe it would be better if he referred to more easily realizable experiments: http://link.aps.org/doi/10.1103/PhysRevLett.102.240401" by A.Eddi et al.

 

[ZapperZ]

According to professor Brian Greene, you can't. People just think they can because for all practical purposes a macroscopic measurement appears accurate, but it never really is.

It NEVER really is?

A "classical particle", by definition, obeys the standard classical laws. Now we can go on and argue that this is nothing more than a set of quantum laws that have undergone a gazillion decoherence, or we can argue that we are observing it using a "coarse-grained" measurements (do a search on here and you'll see that I've written several posts on this). It still does not detract from the issue that you have two separate domains here. If it is THAT easy to explain away the classical behavior, then someone should tell all those people who are working in the mesoscopic scale physics to stop wasting their time and go do something else!

Zz.

 

[boumbh]

It's just a curiosity and I'm searching for an estimation too... Like this kind of a stupid question:

I'm deliberate to apply Newtonian mechanics in a situation where it doesn't apply. On a flat surface (let's state that the Earth is flat and infinite). One train is traveling at 100km/h. An other is traveling at 100km/h on the top of the first train. The speed of the second train is therefore 200km/h. How many trains must I superpose so the top one reaches the speed of light?

This question has an answer even if it states a lot of aberrant assumptions. The answer is 10,792,529 trains (if I'm correct ). I know that to try out this experiment would require the train at the bottom to be very robust and very long (about one million km long to make it possible for all the trains to reach the speed of 100km/h), and a lot of gasoline. Also, the experiment would disprove this calculation since the principle of relativity should make a difference here.

We could also calculate the answer of this stupid question: assuming that my mother doesn't leave home, how much time must I drive my car at 100km/h, to catchup the age of my mother? (Due to time dilatation in the principle of relativity - which has been verified by experiment, so the result is expected to be a good approximation of the reality.)

I would like to know, for example, if I throw a pure graphite ball of 1/2 centimetre radius through a pure graphite wall of 1 millimetre width with a speed of 1m/s. Let's state the ambient temperature at 300K. We neglect the effect of air molecules, gravity, etc. What is the probability of the ball passing through the wall without damaging itself nor the wall? Is there a formula of the quantum principles that, outrageously applied to this case would give a result? Just to have a wrong approximation of an absurd fact, and then try to represent it.

For example : If an answer is 10^(-10^30), we can illustrate it:

If 6,000,000,000 people begins to write zeros right now with an average of 2 per second and per person, without sleeping, drinking nor eating (yes, they would die within 3 days, but), they would need 176 times the age of the universe to write down all the zeros of the number of time you need to throw a graphite ball etc. This is such an understandable illustration...

 

[pedrapgwilym]

As I see the basic nature of QT; every time you throw a tennis ball against a wall, some of it (a vanishingly small some of it) probably does 'tunnel' through the wall. You would have to keep at it for the remainder of the life of the Universe to accumulate enough of the ball on the other side of the wall to make it an observable quantity.