**Nov 11, 2017 06:09 AM (This post was last modified: Nov 11, 2017 06:16 AM by C C.)**

**C C**
Quantum Dream Time

http://fqxi.org/community/articles/display/224

EXCERPT: [...] The nature of time is one of those paradoxes. In the 1960s, physicists John Wheeler and Bryce DeWitt made a major push toward mathematically unifying quantum mechanics and general relativity, deriving a new version of the equation that describes the evolution of quantum systems, the Schrödinger equation, so that it also includes gravity. The problem: time drops out of the equation entirely, leaving physicists who believe that quantum theory is fundamental with a conundrum. [...] This notion of a timeless universe jars with our everyday experience. "It’s clearly meaningless because we see things evolving all the time!" says Maccone.

[...] Conditional probability amplitudes seem to solve Wheeler and DeWitt’s problem of vanishing time, says Maccone. An "inside" observer, correlated with the quantum clock, would see the system change over time, but someone watching from the outside could only observe the static properties of the combined systems. "The state of the universe as seen from the outside is static, but from the inside, it is not," says Maccone. Like the dreamer, the quantum system looks to be at a standstill, while it’s actually alive with action on the inside....

MORE: http://fqxi.org/community/articles/display/224

Ask a Physicist: The Speed of Electricity

http://www.physicscentral.com/buzz/blog/...4074328857

EXCERPT: Last week, a reader named Nabilah wrote in to ask:

What you've been told is correct, but I can see how it'd be confusing—after all, when you hit the light switch, the lights come on instantly! So let's explore what's going on here....

MORE: http://www.physicscentral.com/buzz/blog/...4074328857

http://fqxi.org/community/articles/display/224

EXCERPT: [...] The nature of time is one of those paradoxes. In the 1960s, physicists John Wheeler and Bryce DeWitt made a major push toward mathematically unifying quantum mechanics and general relativity, deriving a new version of the equation that describes the evolution of quantum systems, the Schrödinger equation, so that it also includes gravity. The problem: time drops out of the equation entirely, leaving physicists who believe that quantum theory is fundamental with a conundrum. [...] This notion of a timeless universe jars with our everyday experience. "It’s clearly meaningless because we see things evolving all the time!" says Maccone.

[...] Conditional probability amplitudes seem to solve Wheeler and DeWitt’s problem of vanishing time, says Maccone. An "inside" observer, correlated with the quantum clock, would see the system change over time, but someone watching from the outside could only observe the static properties of the combined systems. "The state of the universe as seen from the outside is static, but from the inside, it is not," says Maccone. Like the dreamer, the quantum system looks to be at a standstill, while it’s actually alive with action on the inside....

MORE: http://fqxi.org/community/articles/display/224

Ask a Physicist: The Speed of Electricity

http://www.physicscentral.com/buzz/blog/...4074328857

EXCERPT: Last week, a reader named Nabilah wrote in to ask:

Electrons carry charge, but I've been told that electrons in a DC circuit actually move slower than a snail, and in an AC circuit, they don't move at all, just shifting to and fro. Then how does that make a lightbulb light up?

Nabilah,What you've been told is correct, but I can see how it'd be confusing—after all, when you hit the light switch, the lights come on instantly! So let's explore what's going on here....

MORE: http://www.physicscentral.com/buzz/blog/...4074328857