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/sci/ - Science & Math

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5168430 No.5168430 [Reply] [Original]

Wait, so if light has no mass. Then what is all that energy doing collecting in plants?

>> No.5168435

http://en.wikipedia.org/wiki/Photosynthesis

>> No.5168494

>>5168435
Still, you cant make something from nothing.

>> No.5168504

>>5168494
It's not nothing. Light is radiation. Radiation does work, ergo it can make something.

>> No.5168511

>>5168504
Then if its something, it must have mass.

>> No.5168513

>>5168494

Photons carry energy. When a photon with the right energy hits a chlorophyll, it knocks off an electron which is passed to a molecule called pheophytin, which then passes it to a quinone molecule. This is the beginning of what is known as the electron transport chain which eventually results in the reduction of NADP to NADPH. This creates a proton gradient across the chloroplast membrane which allows for the synthesis of ATP from ADP. ATP can then be broken down back into ADP by metabolic processes within the plant, a reaction which releases energy.

>> No.5168516

>>5168511

No

>> No.5168517

>>5168511

photons have momentum, but no rest mass.

>> No.5168550

Photons don't actually get converted into something solid. They power the process of photosynthesis. Plants could be more accurately described as being made from air.

>> No.5168662

>>5168430
Light has relativistic mass when moving at high speeds, but at rest it has no mass.

>> No.5168759

>>5168662

>when moving at high speeds

as opposed to what? Light always travels at c

>Light has relativistic mass

This is true, but relativistic mass is a pretty outdated concept. Just say that light has momentum.

>> No.5168764

>>5168550
If plants are maid out of air y they no blow away?
Checkmate athiets

also what is air

>> No.5168772
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5168772

>>5168759
>light always travels at c

>> No.5168773

>>5168772

it does

>> No.5168792

>>5168773
http://www.youtube.com/watch?v=EK6HxdUQm5s

>> No.5168808

How did we first "discover" photosynthesis? as in, what process did we use to find out what was chemically going on during photosynthesis.

>> No.5168815

>>5168792
>http://www.youtube.com/watch?v=EK6HxdUQm5s

The individual photons are always traveling at c. When travelling through a medium the photons are constantly absorbed and the reemmitted, making it seem like light is traveling slowly, when in reality photons are constantly being created, traveling a short distance at c, being absorbed, then being recreated some time later and traveling at c again until they are absorbed again.

>> No.5168817

>>5168808

http://en.wikipedia.org/wiki/Photosynthesis#Discovery

>> No.5168848

>>5168817
well, don't I feel stupid for not checking the Wikipedia article first...

>> No.5168926

Funny story... when an atom/molecule absorbs a photon, its mass *does* increase by a tiny amount. It doesn't matter if the energy goes into exciting an electron, or if it gets transferred into vibrational/rotational modes, or even if it excites a nucleus in some way... it's even possible to measure this, and it's all explained perfectly well by relativity.

>> No.5168935

>>5168815
http://en.wikipedia.org/wiki/Speed_of_light
"the refractive index of air for visible light is about 1.0003, so the speed of light in air is about 90 km/s slower than c"

>> No.5168969

>>5168759
you must be kidding.

>> No.5168970

>>5168935
I don't think you realise that 'refractive index' is a classical approximation.

>> No.5169166

>>5168969

kidding about what?

>> No.5169172

>>5168935

even moving through air, you will never measure a photon moving at any other speed than c. What you are saying is like if I take the long way to get somewhere and someone else takes the short way and we get there the same time that we are traveling the same speed.