Vacuum and quantum uncertainty
Created | Updated Dec 1, 2006
Vacuum is what people call 'empty' space- that deviod of any visible matter/energy. However, there is no such thing as actual empty space, and this entry will describe why.
At the heart of quantum mechanics lies the Heisenberg uncertainty principle. This basically states that is it not possible to know with 100% certainty both of two conjugate values.
For example, it is not possible to know with 100% certainty both a particle's momentum and location.
The most accurately that we may measure something is such that the uncertainty in any two measurements is greater than or equal to half of the reduced Plank's constant.
Here is where this is important for 'vacuum': one of the conjugate uncertainty pairs is time and energy. However, if something is totally empty, that would mean its energy would be exactly 0, for any time (say one second). However, this would violate the unceratinty principle, and thus cannot happen. So basically, space is teeming with particles that have low energy and appear for little time [on the order of 10^(-34) seconds] but they are there.
You are of course right to be sceptical, however, rather amazingly, there is already solid experimental evidence for this phenomenon. Low-energy electrons fired through modified 3-slit apparatus has shown that the elecrons were deflected when there was nothing to do so, and the only explanation is the particles, with their electric charges, as predicted by quantum theory.
Space it self is not acually empty anyway, due to dust particles etc., as well as dark matter and dark energy, which is practically everywhere anyway...
On a side note: vacuum cleaners and other such equipment, indeed anything man-made, with the word 'vacuum' on it is not actually devoid of visible matter, because thermodynamics would ensure that some gaseous particles would still prevail; they just have lower pressure than their surroundings, and that is what causes air to be sucked in/blown out etc.
At the heart of quantum mechanics lies the Heisenberg uncertainty principle. This basically states that is it not possible to know with 100% certainty both of two conjugate values.
For example, it is not possible to know with 100% certainty both a particle's momentum and location.
The most accurately that we may measure something is such that the uncertainty in any two measurements is greater than or equal to half of the reduced Plank's constant.
Here is where this is important for 'vacuum': one of the conjugate uncertainty pairs is time and energy. However, if something is totally empty, that would mean its energy would be exactly 0, for any time (say one second). However, this would violate the unceratinty principle, and thus cannot happen. So basically, space is teeming with particles that have low energy and appear for little time [on the order of 10^(-34) seconds] but they are there.
You are of course right to be sceptical, however, rather amazingly, there is already solid experimental evidence for this phenomenon. Low-energy electrons fired through modified 3-slit apparatus has shown that the elecrons were deflected when there was nothing to do so, and the only explanation is the particles, with their electric charges, as predicted by quantum theory.
Space it self is not acually empty anyway, due to dust particles etc., as well as dark matter and dark energy, which is practically everywhere anyway...
On a side note: vacuum cleaners and other such equipment, indeed anything man-made, with the word 'vacuum' on it is not actually devoid of visible matter, because thermodynamics would ensure that some gaseous particles would still prevail; they just have lower pressure than their surroundings, and that is what causes air to be sucked in/blown out etc.
