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.
They’re traveling in a medium, so they move slower than in space
Due to the random walk caused by multiple scattering, it can take millions of years for a photon to escape the sun after being 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.
... 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.
expatriado@lemmy.world
on 11 Jan 18:43
nextcollapse
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
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.
“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
LanguageIsCool@lemmy.world
on 11 Jan 19:52
nextcollapse
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
on 12 Jan 02:25
nextcollapse
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.
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
on 12 Jan 11:49
collapse
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.
Alright then. But at 0 °F it is not going to melt without your intervention, no matter how sunny it is.
CrazyLikeGollum@lemmy.world
on 12 Jan 16:07
collapse
Absolutely, I don’t disagree with that.
I was just sharing my anecdote as a counterpoint to your minor rhetorical point at the end, because at least to me, it’s funny since eating ice cream outside at -10 degrees is a ridiculous thing to do.
Though, I will note that while ice cream won’t melt at those temperatures, at atmospheric pressure it will still sublimate. So, in that way you could still lose your ice cream without intervention, it would just take a while.
Not quite sure how this would affect melting ice cream. It does fill in some missing pieces to climate models. There are more clouds around than the models predict, which raises the planet’s albedo.
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.
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
Just look at or don’t look at the photons; whichever way it is so they behave like a wave, and then keep your ice cream in the peaks or valleys where the wave doesn’t touch it. 🤷🏻♂️
threaded - newest
Photons don’t gather energy and they definitely don’t move slowly through the sun.
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.
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.
also temperature doesn’t really exist at that scale.
It can definitely take millions of years for photons to leave a star due to dense protons causing collisions.
futurism.com/photons-million-year-journey-center-…
I get what you’re saying but taking a long time is not the same as moving slowly
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.
fair enough
They’re also rapidly making their way and taking a long time.
And cold wind is when slow-moving air hits you at a fast speed.
v = d / t, so technically it is.
but the distance the photon travels is very large, just in random directions
I know I was being pedantic about your comment because I thought it was kinda funny interpreting it out of context.
🤯
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.
I don’t believe in conspiracy theories
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
And from the proton’s perspective, it is created and arrives at its ultimate destination instantly.
One has to imagine whether their life is satisfying provided it contains no journey whatsoever. Only destination.
ackchyually… the destination happens countless times before it leaves the surface of the sun
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.
You so easily could have made this a happy comic instead.
“to land in your Nintendo 64 and to give you the world record”
*last frame is them celebrating together with matching Mario shirts*
“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
Everyone knows the sun’s core makes vitamin D
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)
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.
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?
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.
Alright then. But at 0 °F it is not going to melt without your intervention, no matter how sunny it is.
Absolutely, I don’t disagree with that.
I was just sharing my anecdote as a counterpoint to your minor rhetorical point at the end, because at least to me, it’s funny since eating ice cream outside at -10 degrees is a ridiculous thing to do.
Though, I will note that while ice cream won’t melt at those temperatures, at atmospheric pressure it will still sublimate. So, in that way you could still lose your ice cream without intervention, it would just take a while.
The science on this is relatively recent, but it turns out there is a photomolecular effect on evaporating water that can’t be explained with heat.
news.mit.edu/…/how-light-can-vaporize-water-witho….
Not quite sure how this would affect melting ice cream. It does fill in some missing pieces to climate models. There are more clouds around than the models predict, which raises the planet’s albedo.
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.
Now you got me curious about photons, I mean what is wrong with your tongue? Thoughts and prayers
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
Love this
<img alt="" src="https://lemmy.world/pictrs/image/cbc7d1e0-be29-4293-a1c0-307d246af2e3.gif">
Just eat your ice cream before it melts. Glad i could help.
Or just eat them by night. It’s pretty hard to escape those thousand year photons specifically targeting OP’s icecream by day
Could have been worse:
lemmy.world/post/24169630
it can take tens of thousands of years bouncing around inside the sun before they exit too. always thought that was pretty neat.
Just look at or don’t look at the photons; whichever way it is so they behave like a wave, and then keep your ice cream in the peaks or valleys where the wave doesn’t touch it. 🤷🏻♂️