this post was submitted on 15 Oct 2023
106 points (95.7% liked)
Asklemmy
43945 readers
678 users here now
A loosely moderated place to ask open-ended questions
If your post meets the following criteria, it's welcome here!
- Open-ended question
- Not offensive: at this point, we do not have the bandwidth to moderate overtly political discussions. Assume best intent and be excellent to each other.
- Not regarding using or support for Lemmy: context, see the list of support communities and tools for finding communities below
- Not ad nauseam inducing: please make sure it is a question that would be new to most members
- An actual topic of discussion
Looking for support?
Looking for a community?
- Lemmyverse: community search
- sub.rehab: maps old subreddits to fediverse options, marks official as such
- !lemmy411@lemmy.ca: a community for finding communities
~Icon~ ~by~ ~@Double_A@discuss.tchncs.de~
founded 5 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
A literal flag colored red, if you or the flag is moving towards the other so fast as to blueshift it to green.
Sooooo, wavelengths (λ) become longer when something moves away (redshift) and become shorter when something moves towards you (blueshift).
For a red flag (λ0=610nm) to become a green flag (λ1=549nm), it has to move towards you quite fast. But how fast is 'quite fast'?
Using the formula
flag_velocity / speed of light (c) = difference in wavelengths / starting wavelength
we get
flag_velocity = (610-549) / 610 * c = 61 / 610 * c = 1/10 * c
This means: the flag has to move with about c/10 = 30 000 000 m/s = 108 000 000 km/h = 67 108 100 mph. Yeah, that's quite fast.
(Disclaimer:
use info on own risk
values for λ were chosen in a way to make calculations easy. There is no info on what shade of red or green the flag is. The final result will be about the same.
With speeds at around 10% of c, I should use the formula considering the relativistic doppler effect... However, i wont. Thanks.)
So you're saying I should date her right?
uhhh maybe, idk
Well, they certainly did the math