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Simple dimensional analysis shows that the measurement of the position of physical objects with precision to the Planck length is problematic. Indeed, we will discuss the following thought experiment. Suppose we want to determine the position of an object using electromagnetic radiation, i.e., photons. The greater the energy of photons, the shorter their wavelength and the more accurate the measurement. If the photon has enough energy to measure objects the size of the Planck length, it would collapse into a black hole and the measurement would be impossible. Thus, the Planck length sets the fundamental limits on the accuracy of length measurement.
That's a start, but it really doesn't get into the Heisenberg uncertainty principle, which defines the limits of measuring a particle's position and momentum simultaneously:
originally posted by: Justacasualobserver
a reply to: KyoZero
Maybe this will help
So no measuring technology is expected to overcome this obstacle to exactness.
In quantum mechanics, the 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. For instance, in 1927, Werner Heisenberg stated that the more precisely the position of some particle is determined, the less precisely its momentum can be known, and vice versa...
Thus, the uncertainty principle actually states a fundamental property of quantum systems, and is not a statement about the observational success of current technology.
So a second is exactly 9192631770 cycles because that's what we say it is, by definition. But when you see how the definition has changed to incorporate difficulties in measurement, you can see that measuring it is more difficult than defining it:
Under the International System of Units (via the International Committee for Weights and Measures, or CIPM), since 1967 the second has been defined as the duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom.
In 1997 CIPM added that the periods would be defined for a caesium atom at rest, and approaching the theoretical temperature of absolute zero (0 K), and in 1999, it included corrections from ambient radiation.
Heisenberg sometimes explained the uncertainty principle as a problem of making measurements. His most well-known thought experiment involved photographing an electron. To take the picture, a scientist might bounce a light particle off the electron's surface. That would reveal its position, but it would also impart energy to the electron, causing it to move. Learning about the electron's position would create uncertainty in its velocity; and the act of measurement would produce the uncertainty needed to satisfy the principle.
You thought about it but....and then you post a source that says what I already said? If you were trying to make a point I don't get it.
originally posted by: Deaf Alien
a reply to: Arbitrageur
I thought about the Heisenberg's uncertainty principle but....
At the time, the gyroscopes were the most nearly spherical objects ever made. Two gyroscopes still hold that record, but third place has been taken by the silicon spheres made by the Avogadro project. Approximately the size of ping pong balls, they were perfectly round to within forty atoms (less than 10 nm). If one of these spheres were scaled to the size of the earth, the tallest mountains and deepest ocean trench would measure only 2.4 m (8 ft) high.