Unintended color commands

[A.T.]

@Sagittarius A-Star
Please stop coloring the text. It's unreadable in dark mode.

 

[Dale]

You describe 4 events (E1 ... E4).

E1: clock A shows 100s
E2: clock B shows 80s

E3: clock B shows 100s
E4: clock A shows 80s

I call the coordinates of frame A (x, y, z, t) and the coordinates of frame B (x', y', z', t').

1) => Events E1 and E2 happen simultaneous for observer A: $\Delta t_{21} = t_2 - t_1 = 0s$.
But events E1 and E2 do not happen simultaneous for observer B, if they happen at different $x$ coordinates, according to the Lorentz-transformation: $\Delta t'_{21} \neq 0s$.

2) => Events E3 and E4 happen simultaneous for observer B: ##\Delta t'_{43} = t'_4 - t'_3 = 0s ##.
But events E3 and E4 do not happen simultaneous for observer A, if they happen at different $x'$ coordinates, according to the Lorentz-transformation: $\Delta t_{43} \neq 0s$.

So there is no contradiction.

The Lorentz transformation for time depends on $\Delta x$:
$\Delta t '= \gamma (\Delta t - v \Delta x / c^2)$.
If $\Delta t=0$, then $\Delta t '= -\gamma v \Delta x / c^2$.

The inverse Lorentz transformation for time depends on $\Delta x'$:
$\Delta t = \gamma (\Delta t' + v \Delta x' / c^2)$.
If $\Delta t'=0$, then $\Delta t = \gamma v \Delta x' / c^2$.

It is best to avoid setting explicit colors. In dark mode your whole thing disappears:

@Greg Bernhardt maybe something to think about. Instead of specifying explicit colors perhaps users could be given named colors like “highlight 1” that could be mapped appropriately. That might add a lot of work on your side, so maybe it isn’t worth it. But just an idea.

 

[Sagittarius A-Star]

@Sagittarius A-Star
Please stop coloring the text. It's unreadable in dark mode.

I can't stop coloring the text because I didn't color the text.
I don't work in dark mode. Screenshot:

​

In edit-mode (toggle BB mode) I see color commands, but I didn't enter them.
I will try to delete them.

 

[Dale]

I didn't color the text.

Interesting. There are explicit color directives in there. I wonder how they got there.

Did you do some editing in another program and copy paste the result?

 

[Sagittarius A-Star]

Did you do some editing in another program and copy paste the result?

No. Now I deleted the color-commands.

 

[Ibix]

Interesting. There are explicit color directives in there. I wonder how they got there.

This happened occasionally pre-style update too, but the text wasn't completely invisible in the old dark style.

 

[A.T.]

In edit-mode (toggle BB mode) I see color commands, but I didn't enter them.

OK, sorry. Did you maybe copy & paste the text? If yes, then look for a 'paste as plain / unformatted text' in the context menu of your browser.

 

[A.T.]

@Greg Bernhardt maybe something to think about. Instead of specifying explicit colors perhaps users could be given named colors like “highlight 1” that could be mapped appropriately.

The alternative would be to invert all explicit colors, if the users mode doesn't match the poster's mode.

 

[Sagittarius A-Star]

OK, sorry. Did you maybe copy & paste the text? If yes, then look for a 'paste as plain / unformatted text' in the context menu of your browser.

I deleted the color-commands.

 

[renormalize]

In the process of writing a post to start a new thread, I realized that the editing window is almost 31% wider than the width of the thread window after posting. This can result in truncated equations and rearrangement of where images are placed in the resulting thread post. Is there a reason for this mismatch? Can I tweak a setting to narrow the edit window? Or is this a job for @Greg Bernhardt? (Windows 7, Google Chrome)

 

[A.T.]

Another example (Not sure if unintentional):

Here's my graphical attempt to help you @Mike_bb .

After a summary-and-diagram,
there is a second diagram with an exercise for you to do.


First, here's a simplified summary of radar measurements by Alice (in red) and by Bob (in blue).

• Let P' be the event "[on Bob's worldline] Bob's wristwatch reads 8".
  So, $t_{P',{\rm says\ Bob}}=8$.
  
  Alice assigns coordinates to distant-event P'
  by sending the appropriate light-signal (when her watch reads $t_s=4$) to reach P'
  and waiting to receive its echo (when $t_r=16$).
  She assigns the time $t_{P',{\rm says\ Alice}}=(16+4)/2=10$.
  Alice says the midpoint-event P ("[on Alice's worldline] Alice's wristwatch reads 10")
  is simultaneous with distant-event P' ("[on Bob's worldline] Bob's wristwatch reads 8").
• Similarly (swapping Alice and Bob, and Ps and Qs),
  Let Q' be the event "[on Alice's worldline] Alice's wristwatch reads 8".
  So, $t_{Q',{\rm says\ Alice}}=8$.
  
  Bob assigns coordinates to distant-event Q'
  by sending the appropriate light-signal (when his watch reads $t_s=4$) to reach Q'
  and waiting to receive its echo (when $t_r=16$).
  He assigns the time $t_{Q',{\rm says\ Bob}}=(16+4)/2=10$.
  Bob says the midpoint-event Q ("[on Bob's worldline] Bob's wristwatch reads 10")
  is simultaneous with distant-event Q' ("[on Alice's worldline] Alice's wristwatch reads 8").

Here what it looks like in darkmode:

 

[robphy]

Another example (Not sure if unintentional):



Here what it looks like in darkmode:

I remember selecting black
after having chosen red, trying to get out of red. Similarly for blue.

UPDATE: I see now that I should select "remove formatting".