Why is the Planck length the limit?

So why is the Planck length thought to be the smallest possible length? The simple summary of Mead’s answer is that it is impossible, using the known laws of quantum mechanics and the known behavior of gravity, to determine a position to a precision smaller than the Planck length.

What happens below the Planck length?

At distances below the Planck length, we can’t distinguish ‘separate’ objects, so we can’t say there is a length between them. It’s to do with Heisenberg’s Uncertainty Principle. We can think about ‘half a Planck length’ though, just like we can think about ‘infinity squared +1’.

What is the point of the Planck length?

The Planck length is the scale at which classical ideas about gravity and space-time cease to be valid, and quantum effects dominate. This is the ‘quantum of length’, the smallest measurement of length with any meaning.

Is there something smaller than a Planck length?

If we base our calculations on what we know today, however, there’s no way to go below the Planck scale in terms of distance or time.

What is smaller than a Planck time?

But for example, the wavelength of an electromagnetic wave (which is the same thing as its periodicity in time, multiplied by c) can be much shorter than the Planck length. Arbitrarily short-wavelength photons exist; this is guaranteed by the theory of relativity.

Is the Planck length smaller than an atom?

LP = (hG/2πc3)1/2 . This defines the Planck length, which is 1.6 x 10-35 metres. To give you an idea, let’s compare it with the size of an atom, which is already about 100,000 times smaller than anything you can see with your unaided eye (an atom size is about 0.000 000 0001 meters).

What is Planck quantum theory?

Planck postulated that the energy of light is proportional to the frequency, and the constant that relates them is known as Planck’s constant (h). His work led to Albert Einstein determining that light exists in discrete quanta of energy, or photons.

Is Planck length the size of the universe?

So to summarize, the Planck length is an important order of magnitude when quantum gravity is being discussed, but it is not the fundamental pixel size of the universe. Thanks to John Baez and Nima Lashkari for answering some questions about quantum gravity.

What is Planck time and Planck units?

Planck units are defined based on physical constants rather than human-scale phenomena. So while the second is originally one-86400th of a day, the Planck time is based on the speed of light, Newton’s gravitational constant, and Planck’s (reduced) constant, which is twice the angular momentum of an electron.

How far can light travel in Planck time?

This is how far light can go in a unit of Planck time, because the speed of light is the “Planck speed.” In SI units, this is on the order of 10 -35 meters.