this post was submitted on 11 Jan 2025
658 points (97.7% liked)

Science Memes

11566 readers
2106 users here now

Welcome to c/science_memes @ Mander.xyz!

A place for majestic STEMLORD peacocking, as well as memes about the realities of working in a lab.



Rules

  1. Don't throw mud. Behave like an intellectual and remember the human.
  2. Keep it rooted (on topic).
  3. No spam.
  4. Infographics welcome, get schooled.

This is a science community. We use the Dawkins definition of meme.



Research Committee

Other Mander Communities

Science and Research

Biology and Life Sciences

Physical Sciences

Humanities and Social Sciences

Practical and Applied Sciences

Memes

Miscellaneous

founded 2 years ago
MODERATORS
658
Photons (lemmy.world)
submitted 18 hours ago* (last edited 18 hours ago) by ekZepp@lemmy.world to c/science_memes@mander.xyz
top 37 comments
sorted by: hot top controversial new old
[–] mojofrododojo@lemmy.world 9 points 7 hours ago

it can take tens of thousands of years bouncing around inside the sun before they exit too. always thought that was pretty neat.

[–] Diplomjodler3@lemmy.world 16 points 9 hours ago (1 children)

Just eat your ice cream before it melts. Glad i could help.

[–] portuga@lemmy.world 2 points 7 hours ago

Or just eat them by night. It’s pretty hard to escape those thousand year photons specifically targeting OP’s icecream by day

[–] RustyEarthfire@lemmy.world 4 points 9 hours ago
[–] GooberEar@lemmy.wtf 19 points 14 hours ago (2 children)

From the perspective of the photon, this all happens more or less instantaneously. Or so I have been told. I was also told that my tongue has 5 or 6 zones where different aspects of flavor are detected and I now know that to be wrong. So maybe fuck your ice cream.

[–] psud@aussie.zone 1 points 1 hour ago

more or less instantaneously

That's relativity. The faster a thing goes the slower time runs for them. Photons are travelling at light speed and so they don't experience time at all

[–] portuga@lemmy.world 1 points 7 hours ago

Now you got me curious about photons, I mean what is wrong with your tongue? Thoughts and prayers

[–] hakunawazo@lemmy.world 11 points 13 hours ago
[–] Eheran@lemmy.world 21 points 15 hours ago* (last edited 15 hours ago) (1 children)

It is not direct sunlight that is melting your ice mate. Let's say the scoop has 10 cm² getting blasted from the sun, that's 1 Watt of heat under maximum possible conditions (Sun vertically above you, perfectly black ice, etc.). tl;dr: In total from convenction 1.8 W, condensation 2.5 W and radiation 0.65 W = 4.95 W -> maximum possible sunlight on earth would only increase this by 20 %, more realistic sunlight something like 10 %.

Actual math: Compare that to ambient temperatures of say, 30 °C, and let's again say 10 cm² cross section, which translates to a diameter of 3.57 cm, so a sphere with a surface of 40 cm². The heat transfer coefficient under normal conditions is about 15 W/(m²K), so we get: 15 W/(m²K) * 0.004 m² * 30 K = 1.8 W

Additionally, we have latent heat from water (humidity) condensing on the cold surface: Let's assume a Schmidt number of 0.6, so we get a mass transfer coefficient of: 15 W/(m²K) / [1.2 kg/m³ * 1000 J/(kgK)] * 0.6^(-2/3) = 0.0176 m/s Specific gas constant: 8.314 J/(molK) / 0.018 kg/mol = 462 J/(kgK) So the mass flux (condensation speed) is: 0.0176 m/s * 2000 Pa / [462 J/(kgK) * 273 K] = 0.00038 kg/(m²s)

Given the heat of condensation of 2257 kJ/kg water we thus get: 0.00038 kg/(m²*s) * 2257000 J/kg = 632 W/m²

And thus for our little sphere: 632 W/m² * 0.004 m² = 2.5 W

... Then we also have radiation from the hot surrounding, let's assume 30 °C again, we get: Q = 5.67E-8 W/(m²*K^4) * 0.004 m² * (303 K^4 - 273 K^4) = 0.65 W (omitting radiation from the sky)

[–] JohnDClay@sh.itjust.works 2 points 10 hours ago (1 children)

So made this meme is eating ice cream when it's below or near freezing? Because you still get ice melting below freezing due to radiation.

[–] Eheran@lemmy.world 1 points 1 hour ago (1 children)

Yes, while the radiation puts more energy in than the convective etc. cooling removes. So near 0 this is guaranteed, since the temperature difference from ice to ambient is almost 0 while radiation keeps pumping in something like 0.5 W. But who eats ice at freezing temperatures... And outside?

[–] CrazyLikeGollum@lemmy.world 3 points 54 minutes ago

I have eaten ice cream outside when temperatures were sub-zero Fahrenheit. It's not something I do regularly but it's happened and will probably happen again.

If I want ice cream, then I want ice cream. No other considerations matter.

[–] ryedaft@sh.itjust.works 44 points 18 hours ago (5 children)

Photons don't gather energy and they definitely don't move slowly through the sun.

[–] bdonvr@thelemmy.club 33 points 16 hours ago (1 children)

It can definitely take millions of years for photons to leave a star due to dense protons causing collisions.

https://futurism.com/photons-million-year-journey-center-sun

[–] stebo02@lemmy.dbzer0.com 2 points 14 hours ago (2 children)

I get what you're saying but taking a long time is not the same as moving slowly

[–] pyre@lemmy.world 4 points 7 hours ago (1 children)

v = d / t, so technically it is.

[–] stebo02@lemmy.dbzer0.com 1 points 4 hours ago (1 children)

but the distance the photon travels is very large, just in random directions

[–] pyre@lemmy.world 1 points 58 minutes ago

I know I was being pedantic about your comment because I thought it was kinda funny interpreting it out of context.

[–] stephen01king@lemmy.zip 13 points 13 hours ago (2 children)

Slowly making their way does not equal moving slowly. It describes the time it takes to exit the sun, not the speed of the particle.

[–] dave@feddit.uk 1 points 3 hours ago (1 children)

They’re also rapidly making their way and taking a long time.

[–] Klear@lemmy.world 1 points 1 hour ago

And cold wind is when slow-moving air hits you at a fast speed.

[–] stebo02@lemmy.dbzer0.com 1 points 4 hours ago

fair enough

[–] Artyom@lemm.ee 44 points 17 hours ago
  1. They're traveling in a medium, so they move slower than in space
  2. Due to the random walk caused by multiple scattering, it can take millions of years for a photon to escape the sun after bring produced in the core.

You are right that they don't gather energy, but they do multiply. What would be a single high energy x ray in the core will eventually downscatter into an army of optical photons.

[–] take6056@feddit.nl 8 points 17 hours ago

For photons, their moving relatively slow from the inside to the outside of the sun. Although, I think, it's technically a bunch of photons bumping each other into existence.

[–] Nougat@fedia.io 4 points 18 hours ago

... they definitely don't move slowly through the sun.

They kind of do. While the photons inside the Sun move at a very high speed, they can take up to about 170,000 years to get from the middle of the Sun to the outside, because they change directions a lot on the way.

[–] gubblebumbum@lemm.ee 2 points 17 hours ago

also temperature doesn't really exist at that scale.

[–] expatriado@lemmy.world 18 points 18 hours ago* (last edited 17 hours ago) (1 children)

photons are generated at the core from matter by hydrogen fusion (bigger elements later in the star life), the photons travel to the surface by absorption and re-emission taking about 100,000 years in average to escape, despite traveling at the speed of light. so the slow part depends on perspective

[–] I_Has_A_Hat@lemmy.world 17 points 17 hours ago (2 children)

And from the proton's perspective, it is created and arrives at its ultimate destination instantly.

[–] SnowmenMelt@lemmy.world 6 points 16 hours ago

Thinking about a photon's perspective is nonsensical. You are asking for a frame of reference where the photon is at rest but the very definition of a frame of reference in relativity is one where photon's are travelling at the speed of light. Therefore there cannot be a frame of refernece where a photon is at rest and so a photon can never have a perspective, and neither can anything travelling at the speed of light.

[–] henfredemars@infosec.pub 4 points 17 hours ago (1 children)

One has to imagine whether their life is satisfying provided it contains no journey whatsoever. Only destination.

[–] expatriado@lemmy.world 3 points 17 hours ago

ackchyually... the destination happens countless times before it leaves the surface of the sun

[–] don@lemm.ee 10 points 17 hours ago* (last edited 17 hours ago)

“It took me a hundred thousand years to escape the prison of a motherfucking star, and you have the gall to complain about your little ice cream cone melting?!

Fuck you.”

Me: well when you put it like that

[–] Engywuck@lemm.ee 3 points 14 hours ago
[–] LanguageIsCool@lemmy.world 5 points 16 hours ago

Everyone knows the sun’s core makes vitamin D

[–] Anticorp@lemmy.world 3 points 17 hours ago (1 children)

You so easily could have made this a happy comic instead.

[–] TriflingToad@sh.itjust.works 6 points 17 hours ago* (last edited 17 hours ago)

"to land in your Nintendo 64 and to give you the world record"
*last frame is them celebrating together with matching Mario shirts*

[–] lugal@sopuli.xyz 2 points 18 hours ago

I don't believe in conspiracy theories