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Pess
(Title)
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Reged: 09/12/07

Loc: Toledo, Ohio
Re: C = 0 new [Re: Pess]
      #5998885 - 07/30/13 06:14 PM Attachment (9 downloads)

.

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Ira
Carpal Tunnel
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Reged: 08/22/10

Loc: Mitzpe Ramon, Israel
Re: C = 0 new [Re: Pess]
      #5998996 - 07/30/13 07:32 PM

So why, then, does a lens bend light?

/Ira


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Pess
(Title)
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Reged: 09/12/07

Loc: Toledo, Ohio
Re: C = 0 new [Re: Ira]
      #5999146 - 07/30/13 09:28 PM

Quote:

So why, then, does a lens bend light?

/Ira




The new photon can be re-admitted along varying vectors. The atoms in a mirrored surface (or, more correctly, their electrons) can send them straight backwards so you can see your reflection. Or they can re-emit them along the same vector as glass or air does. Or they can slightly shift the vector and so the image appears shifted.

The photons can even be significantly changed such as a laser hitting a rock with the result of photons being re-emitted at infrared wavelengths (heat)

In summary, photons travel in a straight line, they travel at velocity 'c' until they hit something at which point they cease to exist and their energy is transferred into what stops them.

Pesse (cool beans) Mist


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ColoHank
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Reged: 06/07/07

Loc: western Colorado
Re: C = 0 new [Re: Pess]
      #5999180 - 07/30/13 09:47 PM

Quote:

In regards to a mirror...the photons are absorbed and reemitted in the same direction of travel they came in on so the original photons that struck the mirror are converted to energy when they are absorbed by the atoms of the mirror...this energy is dumped by the atoms in the form of a new photon.





Most of them, anyway. Some are absorbed and converted to heat energy. Thus, reflectance is always less than 100%, the amount of loss determined by the composition and quality of the reflective surface and the wavelength of the light. Also, the re-emitted photons aren't bounced back in the same direction from whence the originals came. If they were, a person could look at a mirror from any angle and still see his or her image. Reflected photon(s) will follow a path that's equal in incidence to the optic normal but opposite in direction to the incoming photon(s).


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StarWars
Mr. Postmaster Man
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Reged: 11/26/03

Loc: At the Gym >Spudtastic<
Re: C = 0 new [Re: Ira]
      #5999413 - 07/31/13 01:37 AM

Quote:

Quote:




Interesting subject!!


I have a flashlight and when the switch is pressed to the on position there is a beam of light.
When switched to the off position the beam of light is gone.

Where did the light go...


I bet there is a big difference between LED produced light and light from the sun!!




Your light is off toward the outer reaches of the cosmos. Whatever part of it isn't blocked by matter, interstellar dust or other junk will just keep on traveling forever at the speed of c. You can never catch up to it.

/Ira





Sounds logical!!


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Qwickdraw
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Reged: 03/03/12

Loc: Ann Arbor, MI
Re: C = 0 new [Re: ColoHank]
      #5999957 - 07/31/13 12:09 PM

Quote:

Also, the re-emitted photons aren't bounced back in the same direction from whence the originals came. If they were, a person could look at a mirror from any angle and still see his or her image. Reflected photon(s) will follow a path that's equal in incidence to the optic normal but opposite in direction to the incoming photon(s).




Sure they do, but only if the angle of incidence equals zero. One of the principles behind a LASER.


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Pess
(Title)
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Reged: 09/12/07

Loc: Toledo, Ohio
Re: C = 0 new [Re: Ira]
      #6000186 - 07/31/13 03:14 PM

Quote:



Your light is off toward the outer reaches of the cosmos. Whatever part of it isn't blocked by matter, interstellar dust or other junk will just keep on travelling forever at the speed of c. You can never catch up to it.

/Ira




I am not so sure. What if the Universe is closed and bounded? So that any straight line comes back on itself?

All one needs to do to catch a photon is stand from where it was emitted and catch it as it comes around.

Pesse (Bring a magazine to pass the time) Mist


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StarWars
Mr. Postmaster Man
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Reged: 11/26/03

Loc: At the Gym >Spudtastic<
Re: C = 0 new [Re: Pess]
      #6001550 - 08/01/13 03:42 PM



Sun light vs. man made light...


When I go outside I can feel the sun light as a pressure on my skin.

Mankind still does not know how to harvest the power of the sun....

Maybe if they build a solar collector with Fresnel lens...


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scopethis
Postmaster
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Reged: 05/30/08

Loc: Kingman, Ks
Re: C = 0 new [Re: StarWars]
      #6002030 - 08/01/13 08:05 PM

since light is absorbed by objects, can one squeeze light out of a sponge that has been exposed to sunlight?

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ColoHank
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Reged: 06/07/07

Loc: western Colorado
Re: C = 0 new [Re: scopethis]
      #6002283 - 08/01/13 10:50 PM

Quote:

since light is absorbed by objects, can one squeeze light out of a sponge that has been exposed to sunlight?




Why not try that and share your findings with us? First, you'll need a sponge. Then, expose it to light. Finally, take the sponge into a very dark room and squeeze it as hard as you possibly can. Be patient; it might take a long time for the light to come out.


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llanitedave
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Reged: 09/26/05

Loc: Amargosa Valley, NV, USA
Re: C = 0 new [Re: ColoHank]
      #6002415 - 08/02/13 12:34 AM

Make sure you have the supplies to clean up the mess afterward.

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Pess
(Title)
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Reged: 09/12/07

Loc: Toledo, Ohio
Re: C = 0 new [Re: ColoHank]
      #6002722 - 08/02/13 08:01 AM

Quote:

Quote:

since light is absorbed by objects, can one squeeze light out of a sponge that has been exposed to sunlight?




Why not try that and share your findings with us? First, you'll need a sponge. Then, expose it to light. Finally, take the sponge into a very dark room and squeeze it as hard as you possibly can. Be patient; it might take a long time for the light to come out.




The sponge atoms almost immediately re-emit absorbed photons...that's why you can 'see' a sponge by looking at it (your eyes detect the re=emitted photons).

However, if you squeeze hard enough to overcome the Coulomb forces, you'll generate plenty of new photons. However, make sure you hire a janitorial service to keep Dave happy because you might not enjoy the experience.

Pesse (clean up on aisle one) Mist


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derangedhermit
Pooh-Bah


Reged: 10/07/09

Loc: USA
Re: C = 0 new [Re: llanitedave]
      #6003681 - 08/02/13 06:18 PM

Quote:

Photons from the Sun's core don't make it directly to the surface. They are generaleast tens of thousands of years to dissipate outward, but it's not because any individual packet is traveling slowly. Also, since it's emitted each time in a random direction, as often as not it gets sent back inward again.



The article said the same thing ("photon absorbed, photon later emitted") was happpening in this case, unless my reading skills have failed entirely.


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wirenut
Pooh-Bah


Reged: 09/21/06

Loc: m'dale Pa
Re: C = 0 new [Re: ColoHank]
      #6005344 - 08/03/13 08:37 PM

Quote:

Quote:

since light is absorbed by objects, can one squeeze light out of a sponge that has been exposed to sunlight?




Why not try that and share your findings with us? First, you'll need a sponge. Then, expose it to light. Finally, take the sponge into a very dark room and squeeze it as hard as you possibly can. Be patient; it might take a long time for the light to come out.



you may want to wear eye protection like a wielders mask or dark sunglasses just in case it soaked up too much light.


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Ira
Carpal Tunnel
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Reged: 08/22/10

Loc: Mitzpe Ramon, Israel
Re: C = 0 new [Re: Pess]
      #6005401 - 08/03/13 09:14 PM

Does the sponge actually reemit the photons or just reflect the same photons that hit it?

/Ira


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scopethis
Postmaster
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Reged: 05/30/08

Loc: Kingman, Ks
Re: C = 0 [Re: Ira]
      #6006766 - 08/04/13 10:33 PM

I was gonna try what many have suggested but my wife won't let me go into a dark room with a sponge...

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Pess
(Title)
*****

Reged: 09/12/07

Loc: Toledo, Ohio
Re: C = 0 [Re: Ira]
      #6008297 - 08/05/13 08:38 PM

Quote:

Does the sponge actually reemit the photons or just reflect the same photons that hit it?

/Ira




1) Photons always travel in a straight line

2) Photons always travel at exactly 'c'

3) Photons do not reflect, bounce off or otherwise change direction. They travel in a straight line until they hit something. Their energy is absorbed (usually by the electron shell of an atom) and then can be re-emitted at a different wavelength, the same wavelength and/or any vector all dependent on the energy of the photon and what it hits.

When you look at a reflection in a mirror, you are not detecting a single photon that 'hit' the mirro5r. You are detecting the re-emitted photons the atoms of the mirror re-emitted after the original photons hit them.

Pesse (clear as mud) Mist


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Ira
Carpal Tunnel
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Reged: 08/22/10

Loc: Mitzpe Ramon, Israel
Re: C = 0 [Re: Pess]
      #6008406 - 08/05/13 09:33 PM

Really? I find this staggering. I never thought of it that way. So, how does gravitational lensing work if photons always travel in a straight line?And if photons are reemitted by whatever they strike why does <angle>i=<angle>r? Why aren't photons reemitted every which way?

/Ira


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llanitedave
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Reged: 09/26/05

Loc: Amargosa Valley, NV, USA
Re: C = 0 [Re: Ira]
      #6008503 - 08/05/13 10:14 PM

Straight lines can curve in gravitational fields.

(The second and third questions have always made me wonder too)


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Pess
(Title)
*****

Reged: 09/12/07

Loc: Toledo, Ohio
Re: C = 0 new [Re: Ira]
      #6009369 - 08/06/13 12:36 PM

Quote:

Really? I find this staggering. I never thought of it that way. So, how does gravitational lensing work if photons always travel in a straight line?And if photons are reemitted by whatever they strike why does <angle>i=<angle>r? Why aren't photons reemitted every which way?

/Ira




What Dave said about gravity & such.

Take a piece of paper.

Draw a razor straight line on it.

Now crumple the paper.

Is the line still straight? What changed?

Pesse (Fun with a 2D Universe) Mist


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