The h Bar

dmckee

12:00 AM

It's not actually required for being a physicist, of course, but various kinds of weirdness seem to be common.

I think part of it is that like hacker culture, physical culture will tolerate oddness if you can produce.

At least, in the decades I've been around. Some of the stories from the early 20th century are not so encouraging.

0celo7

@dmckee Not so encouraging?

dmckee

Much more pressure to conform, and some intolerance of women and people of the wrong skin shade.

obe

12:16 AM

@0celo7 What is your disease?

0celo7

@obe No clue, but it might be morphing into bronchitis or pneumonia.

obe

D:

Sleep and take soup.

NeuroFuzzy

12:40 AM

@StanShunpike what causes this discretization? Resonance in rooms/instruments?

What would cause*

0celo7

Magic.

ManishEarth

1:21 AM

@JohnDuffield Your answer has two references. One is to a book (we don't know if that's mainstream). Show me one paper in a mainstream journal that agrees with you. The second reference is Crowell's answer (which you seem to love to quote), except you misconstrue what he says.

You may not move through a world line, but it is a directed path. The locus of all points you may be found at, and a direction in which time evolution of your frame happens. Crowell doesn't refute this. Crowell only refutes that there's a concrete motion (with a speed and all).

Physics Meta

0

Q: Streamlining the vote to close homework option page

This is a small point, but a lot of my vote to close choices have been about homework questions. Is it possible to have that homework option come up on the first page of the "Why should this question be closed", page, rather than go to another screen to vote? I have no idea of the split betwee...

feature-request

ManishEarth

CTCs and chronology protection are mainstream, according to our policy. I can cite plenty of papers right now in mainstream journals.

CTCs may be impossible, but their study is important. Theories in which functional CTCs are allowed generally need improvement. Vanilla general relativity allows CTCs until you take into account vacuum fluctuations, for example.

3

"Time travel is science fiction" is not a constructive way of adding to a discussion about mainstream CTCs.

Your citations seem to be a string of non sequiturs, actually

or straw men

> Some people will tell you that a gravitational field is negative energy, but it isn't true.

No, that's a straw man. The question is, can a gravitational field have negative energy, which is true, in the case of negative curvature

And none of that follows from

> "the energy of the gravitational field shall act gravitatively in the same way as any other kind of energy" here.

Similarly, this

> You won't get anybody doing that I'm afraid. There can be no backward travel through time because there is no forward travel through time, because there is no motion through spacetime.

does not follow from

> See relativist Ben Crowell saying the same in this answer. You move through space over time, and we depict this as your world line.

So that answer is close to non-mainstream.

obe

1:49 AM

@0celo7 This week will be difficult.

:(

Secret

2:10 AM

In ambient light, I can see from ~411 to ~720 nm
In dim lit conditions (e.g. in a dark room) I can see from 407.5 to 768 nm

The reason I can get such precise readings is because my love of colors caused me to peer through a diffractometer or monochromator that filters sodium lamp lines during my second year analytic chemistry class and I roll the wavelength drum (which is precise down to 0.1 nm) left or right until the color fades to darkness

Being able to see slightly redder than 700 does not always mean a good thing, though. For example, ever since I realise I can see output from a 750…

0celo7

@obe did you do the exercises

obe

2:28 AM

@0celo7 I didn't have time.

I'll do them.

Stan Shunpike

@NeuroFuzzy the discreteness is partly a function of the limits of the brain. There is a limit on how fast or slow a note can be or it wont be perceived at all. So naturally it has to be discretized.

user54412

3:01 AM

@StanShunpike A word of caution: the lower limit on detectable duration need not be the lower limit on detectable duration difference for typical durations. The former is akin to the smallest representable floating point number, the latter to machine epsilon (i.e. the smallest $\epsilon$ such that $1+\epsilon \neq 1$).

Stan Shunpike

3:49 AM

@ChrisWhite hmmm. I would agree those could be very different. Perhaps that is why I find errors in meter so glaringly obvious even when they are small. Would that fit with what you are saying?

user54412

6:14 AM

Ok, who upvoted this?

user54412

-1