# Heisenberg uncertailnly principal

the uncertainty principle, also known as Heisenberg's uncertainty principle, is any of a variety of mathematical inequalities asserting a fundamental limit to the precision with which certain pairs of physical properties of a particle, known as complementary variables, such as position x and momentum p, can be known simultaneously.

Introduced first in 1927, by the German physicist Werner Heisenberg, it states that the more precisely the position of some particle is determined, the less precisely its momentum can be known, and vice versa The formal inequality relating the standard deviation of position σx and the standard deviation of momentum σp was derived by Earle Hesse Kennard later that year and by Hermann Weyl in 1928:

The position and momentum of a particle cannot be simultaneously measured with arbitrarily high precision. There is a minimum for the product of the uncertainties of these two measurements. There is likewise a minimum for the product of the uncertainties of the energy and time.

$$\Delta x \Delta p \geq \frac{h}{4 \pi}$$ $$\Delta E \Delta t \geq \frac{h}{4 \pi}$$ $$\Delta x = \text{uncertainty in position}$$ $$\Delta p = \text{uncertainty of momentum}$$ $$\Delta t = \text{uncertainty in time}$$ $$\Delta E = \text{uncertainty in energy}$$ $${h} = \text{Planck's constant}$$ $$\pi = pi$$

This is not a statement about the inaccuracy of measurement instruments, nor a reflection on the quality of experimental methods; it arises from the wave properties inherent in the quantum mechanical description of nature. Even with perfect instruments and technique, the uncertainty is inherent in the nature of things.

One of the biggest problems with quantum experiments is the seemingly unavoidable tendency of humans to influence the situati¬on and velocity of small particles. This happens just by our observing the particles, and it has quantumphysicists frustrated. To combat this, physicists have created enormous, elaborate machines like particle accelerators that remove any physical human influence from the process of accelerating a particle's energy of motion.

Still, the mixed results quantum physicists find when examining the same particle indicate that we just can't help but affect the behavior of quanta -- or quantum particles. Even the light physicists use to help them better see the objects they're observing can influence the behavior of quanta. Photons, for example -- the smallest measure of light, which have no mass or electrical charge -- can still bounce a particle around, changing its velocity and speed.