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Author Topic: Can the door be unlocked using quantum uncertainty?  (Read 2506 times)

Offline Atomic-S

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Let us suppose that I have arrived home, and prepare to unlock the door, only to discover that I forgot my house key, which is inside the house. If I had the key in hand, I would be able to retrieve it and unlock the door and then put the key back where it was. I am aware that the action of putting the key back where it was is at least conceptually possible, much as is finding, outside a nucleus, a subatomic particle that belongs to the nucleus, that phenomenon being blocked only by the potential barrier that keeps it inside the nucleus. I recall that despite the potential barrier, such particles are sometimes found outside the nucleus, enabling the nucleus to decay in defiance of the conservation of energy. So it occurs to me that the possibility of the key being returned to its current location after unlocking the door, suggests that I could borrow against that fact long enough to obtain the key and unlock the door. Any way to exploit this idea?


 

Offline CliffordK

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Re: Can the door be unlocked using quantum uncertainty?
« Reply #1 on: 21/08/2012 03:31:20 »
I find it is quicker to climb through the window as one might spend a lot of time sitting by the door wishing the key was in one's hand (or that the lock tumblers were magically in a different position).
 

Offline Emc2

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Re: Can the door be unlocked using quantum uncertainty?
« Reply #2 on: 21/08/2012 08:02:43 »
one thing you have to remember, is that no matter how far away from understanding the "laws" that apply to all matter on the sub-atomic level humanity may be.   There are laws that even these minute particles must follow.

  the trick is getting the technology and understanding as to exactly how those laws work.

 while it is true, that uncertainty can lead to almost anything being possible, in reality there is order and certainty in all of nature.

  human beings have only been technology and observationally active for a small fragment of a section of the history of all of it, and it is foolish to think that in such a short time, that we are going to unlock all of the secrets of the universe.......

  but it is fun as heck to try and figure it all out, lol...
 

Offline lightarrow

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Re: Can the door be unlocked using quantum uncertainty?
« Reply #3 on: 21/08/2012 12:28:04 »
Let us suppose that I have arrived home, and prepare to unlock the door, only to discover that I forgot my house key, which is inside the house. If I had the key in hand, I would be able to retrieve it and unlock the door and then put the key back where it was. I am aware that the action of putting the key back where it was is at least conceptually possible, much as is finding, outside a nucleus, a subatomic particle that belongs to the nucleus, that phenomenon being blocked only by the potential barrier that keeps it inside the nucleus. I recall that despite the potential barrier, such particles are sometimes found outside the nucleus, enabling the nucleus to decay in defiance of the conservation of energy. So it occurs to me that the possibility of the key being returned to its current location after unlocking the door, suggests that I could borrow against that fact long enough to obtain the key and unlock the door. Any way to exploit this idea?
I actually don't know the answer, but I know that energy conservation is always valid, you can't challenge it.
 

Offline damocles

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Re: Can the door be unlocked using quantum uncertainty?
« Reply #4 on: 21/08/2012 22:07:25 »
There is no real challenge to energy conservation,
BUT
there is a time/energy uncertainty relationship analogous to the position/momentum relationship, which means that you can "borrow" energy that is not really there, provided that you are doing it for a sufficiently short time.
The "uncertainty" (meaning statistical standard deviation of a distribution) in energy multiplied by the uncertainty in the time of observation must be greater than or equal to (Planck's constant)/4π. It is therefore theoretically possible to fool the auditors who are checking up on the energy accounting, provided you repay an energy debt within a short enough time. This is one basis you can use for providing a model of quantum-mechanical tunnelling.
 

Offline imatfaal

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Re: Can the door be unlocked using quantum uncertainty?
« Reply #5 on: 22/08/2012 15:22:20 »
There is no real challenge to energy conservation
BUT
it gets very difficult in general relativity to be strict about it - physics faqs sums it up energy conservation in curved spacetime and importantly the flat limits as 
Quote
In special cases, yes.  In general it depends on what you mean by "energy", and what you mean by "conserved".
 

Offline Bored chemist

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Re: Can the door be unlocked using quantum uncertainty?
« Reply #6 on: 22/08/2012 20:49:03 »
It may be quicker to just hope you quantum tunnel through the door.
 

Offline CliffordK

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Re: Can the door be unlocked using quantum uncertainty?
« Reply #7 on: 22/08/2012 23:03:41 »
It may be quicker to just hope you quantum tunnel through the door.
If you get a good run at it....
You may get a quantum tunnel through it.
Or...
You may end up with either a sore shoulder, or a shattered door frame...  or both.
 

Offline lightarrow

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Re: Can the door be unlocked using quantum uncertainty?
« Reply #8 on: 23/08/2012 10:30:06 »
There is no real challenge to energy conservation,
BUT
there is a time/energy uncertainty relationship analogous to the position/momentum relationship, which means that you can "borrow" energy that is not really there, provided that you are doing it for a sufficiently short time.
The "uncertainty" (meaning statistical standard deviation of a distribution) in energy multiplied by the uncertainty in the time of observation must be greater than or equal to (Planck's constant)/4π. It is therefore theoretically possible to fool the auditors who are checking up on the energy accounting, provided you repay an energy debt within a short enough time. This is one basis you can use for providing a model of quantum-mechanical tunnelling.
This is a legend I also believed for a long time. People much more prepared than me guaranteed me that energy conservation is *always* valid. I remember some discussions about this in "Physics Forums"; make a research there, if you want.
 

Offline damocles

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Re: Can the door be unlocked using quantum uncertainty?
« Reply #9 on: 23/08/2012 11:00:53 »
That is OK lightarrow. It is not necessary to believe in this particular representation because there are always alternative ways of looking at things to get around quantum mechanical tunnelling and spectral line broadening -- the two main areas where I have found this idea useful. The ideas of exponential decay of transmitted wave when a moving wavefunction is reflected from a barrier for tunneling, and spectral broadening as the result of doppler shift arising from uncertain collision parameters, each involve only position/momentum uncertainty, and can readily be transformed to/from time/energy uncertainty. I find that the latter is much more convenient, but am quite prepared to mend my ways and transform my equations for those who do not want to believe that it is valid.
 

Offline Emc2

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Re: Can the door be unlocked using quantum uncertainty?
« Reply #10 on: 24/08/2012 08:17:39 »
belief depends on "proof" or acceptance in absence of truth...just as in all things...

  it is possible, considering that we know so little of the sub atomic world, yet do know some cool things...

  but a lot of theories are possible, and very plausible....

 since none of us have proof on many of these things, it comes down to believing someone else's "best" guess, or coming up with your own "best" guess,

but this is how questions get answered "sooner or later" in all things..
 

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Offline lightarrow

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Offline evan_au

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Re: Can the door be unlocked using quantum uncertainty?
« Reply #12 on: 24/08/2012 11:40:16 »
Every particle has a wave function, representing the probability that you will find it in a particular position if/when you measure its position. It is possible that you may find an electron distant from the nucleus of its atom, with a finite probability.

However, the probability of finding a macroscopic object like a key a few yards from its location on the other side of the door is vanishingly small.

If you tried to "borrow" energy to move it, you would have to borrow it for such a small time that you would not have time to unlock the door.
 

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Re: Can the door be unlocked using quantum uncertainty?
« Reply #12 on: 24/08/2012 11:40:16 »

 

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