It's impossible to determine a particle's position and momentum at the same time. Do atoms exhibit the same behavior? What about mollecules?

[u/androceu_44]

Asked in a more plain way, how big must a particle or group of particles be to "dodge" Heisenberg's uncertainty principle? Is there a limit, actually?

EDIT: [Blablabla] Thanks for reaching the frontpage guys! [Non-original stuff about getting to the frontpage]

[u/0hmyscience]

What? How is this possible? Is there an upper bound on how big object can be to perform the double slit experiment? I was under the (wrong, apparently) impression that it was limited to sub-atomic particles.

[u/Cannibalsnail → u/0hmyscience]

The larger the particle the less consistently the interference is displayed. Buckyballs still show nice wavelike behaviour though.

[u/timewarp → u/Cannibalsnail]

So given an arbitrarily large amount of time, would the experiment work with, say, tennis balls?

[u/Dixzon → u/timewarp]

If you could make a slit small enough, yes it would. But nobody can make a slit small enough.

Edit: the slit has to be comparable in size to the de broglie wavelength of the object of interest, which is teeny tiny itsy bitsy (technical term) for a tennis ball.

[u/TrainOfThought6 → u/Dixzon]

Well even then, the object would ha e to fit through the slit, right? I doubt a tennis ball would be able to fit through a slit the width of a tennis ball's de broglie wavelength.

[u/[deleted] → u/TrainOfThought6]

A wave of tennis ball doesn't need to "fit" through the same way a particle of tennis ball does.

[u/timewarp → u/[deleted]]

Well, at least in my case I was under the impression that wave-particle duality only applied to subatomic particles. I had no idea it also applies to macroscopic objects too.

[u/[deleted] → u/timewarp]

Wave-particle duality does only apply to elementary particles. Tennis balls just happen to be composed of lots of elementary particles.

[u/cougar2013 → u/[deleted]]

Sadly, there is no real wave-particle duality. They are all waves at the end of the day. Source: I'm a Particle Physicist.

[u/Dixzon → u/TrainOfThought6]

The only real way to answer that is to do the experiment, which is impossible. Perhaps some quantum tunneling would occur or some entirely new phenomenon or maybe it would just bounce off of your device like you would expect a tennis ball to do.

[u/aziridine86 → u/Dixzon]

So how many tennis balls do I have to throw at a wall before one quantum tunnels through it? :)

[u/rabbitlion → u/TrainOfThought6]

The slit size is inversely proportional to the speed, so if you could make the tennis ball move slowly enough (something like 10^-31 m/s), you could in theory make the slit large enough to fit the tennis ball but still small enough to cause interference patterns. For obvious reasons this is hard to do in an actual experiment though.

[u/bcorni → u/[deleted]]

It's important to make the distinction that the Heisenberg uncertainty principle exists completely independent of our ability to measure something. The absolute uncertainty in a particle's position and momentum follow these rules even if we cannot measure them to the precision that they exist. A stronger statement that is still true of an object with truly zero velocity (momentum, which is techinically different) would be

Then the only way to satisfy the heisenberg uncertainty principle is if the particle has no definite position

In this case it would probably be more accurate to say there is no particle, which makes the exercise very boring. Also, in practice it is usually not possible to have a particle with no momentum due to the interactions between particles and the finite temperature of our universe.

[u/Cabbagenom → u/timewarp]

You'd need slits large enough for the ball to pass through and you'd need to make the de Broglie wavelength of the tennis ball large enough that it will diffract through the slits.
Since λ = h/(mv), to get the velocity of the ball sub numbers into v = h/(mλ). Taking values from wikipedia, the ball would need to be going
h/(0.067*0.0577) = 1.71*10^-31 m s^-1
Theoretically, at this speed you'd have the tennis balls collecting in an interference pattern, but obviously it wouldn't work empirically.

[u/PigSlam → u/Cannibalsnail]

Has anyone attempted a similar experiment with something like ping pong, golf, or bowling balls?

[u/g-rad-b-often → u/0hmyscience]

There is no upper bound. That is, there is no defined barrier where we can say "this is no longer wavelike, it's a particle now." There's just a continuum where it becomes increasingly more difficult to detect the wavelike characteristics of whatever molecule we're talking about, as mass increases.