Physics X Extraordinary Concepts in Physics Distance Scales

Physics X Extraordinary Concepts in Physics Distance Scales in the Universe II taught by: Robert J. Nemiroff

Physics X: About This Course a. Pronounced "Fiziks Ecks" b. Reviews the coolest concepts in physics c. Being taught for credit at Michigan Tech a. b. c. d. Michigan Tech course PH 4999 Aimed at upper level physics majors Light on math, heavy on concepts Anyone anywhere is welcome a. Wikipedia, web links, and lectures only d. No textbook required

Scales of the Universe: Motion: Distance over Time a. Velocity: dx/dt a. minimum: zero b. minimum predictable: Δp Δx > h; v ~ Δv > (h/m) Δx c. maximum: c (speed of light) b. Acceleration: d 2 x/dt 2 a. minimum: zero b. maximum: unknown c. Higher orders of motion a. Must be nonzero for an object at rest to move b. Jerk: d 3 x/dt 3; Jounce: d 4 x/dt 4 c. Even higher orders. Is there a limit?

Universe: Analog or Digital? a. Analog Principle a. Everything is fuzzy if you look close enough b. A line on a page appears crisp only from afar c. Uncertainty principle b. Digital Principle a. Everything is discrete if you look close enough b. Seemingly fuzzy patterns are made of discrete dots c. Quanta, string theory c. Which is more correct?

Planck Units a. Unitless measures of length, mass, time, and charge to which measured quantities can be normalized • Composed of fundamental constants o c, G, h, ε 0 • More basic than length, time, mass, and charge? o c => m/s o G => m 3/kg/s 2 o h (angular momentum) => m 2 kg/s o ε 0 => C 2 s 2 /kg/m 3

Planck Length a. ~1020 times smaller than the radius of a proton b. Never been imaged c. Significance experimentally unknown d. Black holes: lp 2 ~ minimum area of an event horizon (possibly) e. String theory & Loop quantum gravity: lp 2 ~ minimum area that a single bit of information might occupy.

Planck Mass a. ~2 x 10 -8 kg • Defined by when the Compton wavelength (h/mc) is equal to the Schwarzschild radius (2 Gm/c 2) for a particle • Not minuscule: a flea can have a mass of several Planck masses

Planck Time a. The time it takes for light to travel one Planck length. a. Before this time near the Big Bang, the universe was so dense that quantum effects will dominate general relativistic (GR) gravitational effects.

Interactive Universe Zoom Secret Worlds: The Universe Within

Movies and Interactive Web Sites a. Powers of Ten a. 1977 movie version of 1957 book "Cosmic View" b. Earlier version: 1968 Cosmic Zoom