this post was submitted on 24 Jan 2025
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Science Memes

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[–] [email protected] 5 points 6 days ago (1 children)

Uh, Einstein was Jewish and Hugo Boss made the SS uniforms. This is a bit odd.

[–] [email protected] 4 points 6 days ago (1 children)

How on earth would an average person looking at this pic of Cavill know it's Hugo Boss?

[–] [email protected] 2 points 6 days ago (1 children)

I am sorry, I thought this was a Hugo Boss ad and that that was the joke. I have never heard of Cavill?

[–] [email protected] 4 points 6 days ago (1 children)

That's the beautiful man in the photograph

[–] [email protected] 2 points 6 days ago (1 children)

As dumb as I am, that I understood from the first reply. Appreciated the help!

[–] [email protected] 2 points 6 days ago (1 children)

Sorry, wanted to make a joke :D he's a pretty famous actor. He played Geralt of Rivia in The Witcher, Superman in a bunch of DC movies, as well as many other roles.

[–] [email protected] 2 points 5 days ago

I like the mood here. Also I looked him up and he is more famous than I understood. Nice!

[–] [email protected] 66 points 1 week ago* (last edited 1 week ago) (2 children)

Uh, that discovery actually predated Einstein. He simply explained how the speed of light was constant for all observers

To be more accurate actually, he and his first wife explained it

[–] [email protected] 28 points 1 week ago (1 children)

You mean Mileva Marić and her husband?

[–] [email protected] 8 points 1 week ago (1 children)

I was blanking on her name. Sadly she is almost never given the credit she deserves

[–] [email protected] 10 points 6 days ago (1 children)

Didn't want to make you fell like you have defend yourself, just wanted to turn it around and shitpost. But yeah, she rarely does.

I was also lowkey referencing the famous photo caption from am interview with "Amal Clooney, famous and successful lawyer and human rights activist, and her husband, an actor". Referring to a certain George.

[–] [email protected] 5 points 5 days ago (1 children)

Oh I didn't feel like you were attacking me, rather I appreciated you posting her name

[–] [email protected] 5 points 5 days ago

ಠ_ಠ

This is unaceptable...you have to be assholes to each other.

[–] [email protected] 7 points 1 week ago

Einstein proved time is relative just so he could take credit for it

[–] [email protected] 46 points 1 week ago (2 children)

And it is remarkably consistent at doing that.

[–] sik0fewl 24 points 1 week ago

Relatively consistent.

[–] [email protected] 8 points 1 week ago (2 children)
[–] [email protected] 1 points 5 days ago (1 children)

But when you think about light's speed in medium it seems like absorption and re emission which shifts light's net velocity. The speed of light between the interaction is still c. That becomes obvious if you zoom into matter and find its mostly empty likr vaccum

[–] [email protected] 2 points 5 days ago (1 children)

No, that's not really a useful way of modeling it for the case of light traveling through a linear medium.

The absorption/re-emission model implicitly localizes the photons, which is problematic


think about it in an uncertainty principle (or diffraction limit) picture: it implies that the momentum is highly uncertain, which means that the light would get absorbed but re-emitted in every direction, which doesn't happen. So instead you can make arguments about it being a delocalized photon and being absorbed and re-emitted coherently across the material, but this isn't really the same thing as the "ping pong balls stopping and starting again" model.

Another problem is to ask why the light doesn't change color in a (linear) medium


because if it's getting absorbed and re-emitted, and is not hitting a nice absorption line, why wouldn't it change energy by exchanging with the environment/other degrees of freedom? (The answer is it does do this


it's called Raman scattering, but that is generally a very weak effect.)

The absorption/emission picture does work for things like fluorescence. But Maxwell's equations, the Schrödinger equation, QED


these are wave equations.

[–] [email protected] 1 points 4 days ago* (last edited 4 days ago)

I wouldn't say its a useful way, but if you think about it, everything is vaccum if you zoom enough. Also absorption can mean different things though so keep that aside and think of it as some interaction going on which in effect slows it down.

Now i looked up on youtube and this is what i meant (timestamp included). I was looking for 3b1b explaination but this one works too. It's arguable if we can call it absorption or not, and what I said before might be ambiguous. But this guy explains it well

Edit: The 3b1b explaination is either in this video or in this one or maybe a combination of both

[–] remotelove 12 points 1 week ago (2 children)

Yes, but light always travels at the speed of light, regardless of its speed. It travels at c in a vacuum.

[–] [email protected] 10 points 1 week ago (1 children)

Light is never late, nor is it early, it arrives precisely when it means to.

[–] [email protected] 2 points 6 days ago* (last edited 6 days ago)

Since an observer traveling through space at the speed of light experiences no time from the beginning of their journey until they decelerate (since their 4-velocity vector has non-zero values only in the 3 dimensions of space), photons don't just arrive precisely when they mean to, from the moment they are emitted, they have already arrived.

[–] [email protected] 2 points 1 week ago

Dispersion and nonlinearities would like to have a word ;)

[–] [email protected] 40 points 1 week ago (1 children)

He also discovered that the speed of light equals c.

[–] [email protected] 34 points 1 week ago (1 children)

Where c is defined as the speed of light

[–] [email protected] 9 points 1 week ago (1 children)

And that's why we take vitamin C!

[–] [email protected] 1 points 6 days ago (1 children)

And why pirates drink coffee. "Boo, tea!" they cry

[–] [email protected] 2 points 6 days ago (1 children)
[–] [email protected] 1 points 6 days ago

Now you know how I felt through this whole comment chain

[–] [email protected] 20 points 1 week ago (3 children)

I'm reasonably sure that Einstein's breakthrough was more that he assumed light only travels at the speed of light and the all the equations worked.

Every experiment since has confirmed it.

[–] [email protected] 32 points 1 week ago* (last edited 1 week ago) (2 children)

Technically everything moves at c (the speed of light) through spacetime, all the time. Most objects that have mass spend the majority of their motion in the time part, and thus move relatively slowly in space. If an object moves fast in space (where fast is a significant fraction of c) then it moves noticeably slower in time because the total spacetime vector value is always c.

Photons, being massless, do not move through time at all, and move through space at c.

[–] remotelove 16 points 1 week ago (1 children)

That'll break a few brains. To elaborate with an example: From the perspective of a photon, it's "life" is over as soon as it begins. Even though it takes about 8 mins for a photon to travel from the sun to the earth from our perspective, no time at all has passed for it.

(Correct me if I misspoke.)

[–] [email protected] 5 points 6 days ago (1 children)

Light is generally better modeled by a wave, so I would say the wave doesn't experience time. Photons are the smallest unit of energy that can be transferred between a light wave and a different particle. They have momentum and direction, but they don't really travel exactly. They just mediate the force between light waves and matter.

Worded differently, a fermion (massive particle) within an electromagnetic (light) wave with a frequency of f may absorb some multiple of h x f joules of energy, where h is a very small constant. There is no way for the wave to transfer less than hf joules to the particle at a time. There is no need to think of photons as anything other than the smallest possible quantization of the electromagnetic wave rather than a particle of light. There's no need to think of it existing for any amount of time or space.

[–] remotelove 4 points 6 days ago (1 children)

Photons are the smallest unit of energy that can be transferred between a light wave and a different particle.

That is a much better description than what I have heard for the last 30 years: "A photon is a packet of energy". That made no sense to me back then, and makes no sense to me now and, IMHO, doesn't quite give a good visualization. It's a placeholder, and I suppose it is slightly accurate depending on how "packet" is defined.

[–] [email protected] 2 points 6 days ago

That's awesome, and I totally agree. Everyone already intuitively knows that waves carry energy. We've all heard of tsunamis and earthquakes. The only difference on the quantum scale is that the amount of energy transferred is discretized.

[–] [email protected] 7 points 1 week ago* (last edited 1 week ago)

To add to this, this is always relative to an observer. If an object moves fast in space compared to you then it moves slower in time compared to you.

[–] [email protected] 8 points 1 week ago (1 children)

Any speed that light travels is the speed of light

[–] [email protected] 3 points 1 week ago

The real breakthrough

[–] [email protected] 3 points 1 week ago

The other way around. Experiments said that light always moves at C and he deduced what follows from that for space time.

[–] [email protected] 13 points 1 week ago* (last edited 1 week ago)

Camera: *flash*

“Fuck you photons, next time. Again.”

[–] [email protected] 11 points 1 week ago (2 children)

Yeah, but is it a wave or a particle, eh, Einstein? Answer that!

[–] [email protected] 21 points 1 week ago (1 children)
[–] [email protected] 3 points 1 week ago

Holy Minkowski spaces, Batman! It's the old man himself!

[–] [email protected] 5 points 1 week ago

Well, he did get a Nobel price for saying it's a particle.

[–] [email protected] 6 points 1 week ago

Put a monocle on him and make it The Speed Of Causality.