this post was submitted on 15 Oct 2023
111 points (95.9% liked)
Asklemmy
43803 readers
767 users here now
A loosely moderated place to ask open-ended questions
Search asklemmy ๐
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
Of ur moving fast enough the doppler effect.
Did you consciously try to make yourself look as dumb as possible?
They're just not moving fast enough, or possibly in the right direction.
Sooooo, wavelengths (ฮป) become longer when something moves away (redshift) and become shorter when something moves towards you (blueshift).
For a red flag (ฮป0=610nm) to become a green flag (ฮป1=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 ฮป 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.)
Well, instead of moving the flag, we could collapse the space in between us rapidly. Would that be easier? I think I have some dark energy around here somewhere...
pssst hey you missed the conversion from seconds to hours, your answers are in kilometres/miles per second and need to be another 3600 times larger.
Are you sure about that? From m/s to km/h you multiply by 3600 (for the time) and divide by 1000 (for the distance) which leads to a factor of 3.6.
Personally i always remember 25 m/s = 90 km/h = 56 mph because of the somewhat round numbers.
They did the math
They did the monster math
Just checked ur comment history and i think ur a little insecure about ur intelegence. Dont worry ill let u have the last word.