If you have the chance to see a rose blue shift, you’re probably already dead.
Roses
Submitted 6 days ago by fossilesque@mander.xyz to science_memes@mander.xyz
https://mander.xyz/pictrs/image/656b4eca-c58e-4261-88c3-36288a8dd5d1.png
Comments
Ganbat@lemmy.dbzer0.com 6 days ago
TowardsTheFuture@lemmy.zip 6 days ago
I… how fast would it need to be going for a red rose to look blue.
gandalf_der_12te@feddit.org 5 days ago
assuming we want the frequency to double,
going by this formula: en.wikipedia.org/wiki/Redshift
with the wavelength ratio 1 + z we want 1 + z = 1/2 so v/c = -3/5 c = -0.6c if i calculated correctly (i did this in my head without a napkin), where the source moves away from the observer with velocity v. so it would have to move towards you quite rapidly.
InvalidName2@lemmy.zip 6 days ago
According to Ebay, Amazon, Walmart, Temu, Etsy, and so on, you can buy blue rose seeds.
morto@piefed.social 5 days ago
They manage to do it by delivering them to you reeeeeealy fast
j5y7@sh.itjust.works 6 days ago
This one made me smile.
Slovene85@sh.itjust.works 5 days ago
Roses are red
Roses are blue
Dress is blue/black
It’s white and gold too
Kongar@lemmy.dbzer0.com 6 days ago
I mean that’s cute but not quite correct right? Depends on their distance from you I think. A very very long distance.
Contramuffin@lemmy.world 6 days ago
You’re confusing 2 different but related concepts. Blueshift and redshift does depends only on velocity. In the cosmological sense, redshift (the opposite of blueshift) occurs because everything is moving away from everything else due to the expansion of the universe, and so the distance of an object can be calculated based on how much redshift there is in the light. Basically, on a cosmological scale, distance and velocity are connected
Kongar@lemmy.dbzer0.com 6 days ago
Right, I was thinking of redshift. But now I’m even more intrigued. How does a thing moving toward me shift light blue? It’s not like the space inbetween us is shrinking…. And the speed of light is constant…
What the heck is blue shift? I need to go hit Google/wikipedia/something smarter than me ;)
gandalf_der_12te@feddit.org 5 days ago
actually cosmological redshift occurs not so much because a velocity difference between source and observer, but because space is expanding while the wave is in it, or so i was told. so the wave continuously gets stretched out, which causes it to redshift. calculating it that way gives slightly different results from normal doppler redshift, i think. so it does matter.
gandalf_der_12te@feddit.org 5 days ago
Basically, on a cosmological scale, distance and velocity are connected
yeah btw to comment on this: this phenomenon is probably more important than it seems at first glance. because it implies that, while there is neither an absolute position nor an absolute velocity in relativity theory, there is a connection between position and velocity. so, for each position in space, there is an associated zero velocity, or reference velocity, which is the velocity of the cosmos at that location. or at least that’s what i’m lead to believe.
now, this is not at all obvious. one might argue that that’s bullshit, frankly, but it appears at least 3 times in various aspects of standard models of cosmology:
- for one, contemporary microwave background. it’s said to be isotropic (and has the shape of a black body radiation) but only if the observer moves with a certain velocity. if you move extremely fast in either way, one side gets blueshifted while the other one gets redshifted, so it’s not isotropic anymore. there’s exactly one (finite!) velocity for which it is most isotropic, which is the “average velocity” of the radiation.
- then there’s the whole question of how a vacuum energy could possibly be lorentz-invariant. the way i see it, if there is radiation in space everywhere, then that would have to be similar to microwave background (just at another frequency). so it again would have to have a certain average velocity. note that this is different from the previous point because while the previous point uses other objects as reference frame (that might not be present in an alternative universe), this one does not. you cannot have a universe with the same laws as ours that’s completely empty of vacuum energy, so there’s always some reference frame.
- then there’s the issue that if you go really far back in time, the cosmic expansion is not lorentz-invariant. well, at least not if you look at this curve:
if you tilt it somewhat, it’s not isotropic anymore. because while expansion rate is accepted to vary with time, it should be homogenous in space. now, if you do a lorentz-transformation, these two things cannot hold at the same time. so, cosmic expansion wouldn’t be lorentz-invariant?
Elting@piefed.social 6 days ago
The doppler effect you can hear when something loud passes you happens to light too. It would have to be aproaching very fast indeed however to make a red rose appear blue. (Like fast enough to fuse atoms in the atmosphere)
Kongar@lemmy.dbzer0.com 6 days ago
Thanks! I just learned this - makes sense at fast speeds. Just never thought it was from anything other than space expanding :)
Draconic_NEO@mander.xyz 5 days ago
Doppler shift is based on speed, the result of red shift is that stuff which is moving away fast enough to produce red shift is far away by virtue of being fast and stuff and stuff that is blue shifted needs to be far away or it will collide with you very quickly or just pass you by. The relative speeds required for doppler shift are pretty high speeds so you normally observe it in stuff that’s far away, but distance isn’t really a requirement for doppler shift to happen or be observed.
garbage_world@lemmy.world 6 days ago
Clean
Septimaeus@infosec.pub 5 days ago
[deleted]tetris11@feddit.uk 5 days ago
Smush them together and then have a poo
FTFY
BlueberryWalnut@sopuli.xyz 6 days ago
Roses are red Violets are red Poppies are red Oh fuck the garden is on fire again
boonhet@sopuli.xyz 6 days ago
Again?!