Daymare17 Posted November 1, 2005 Share Posted November 1, 2005 My physics teacher says that there is such a thing as darkness rays! Is this true?? He says that when you hold a shroud in front of a spotlight, the spotlight emits darkness rays onto the wall in front of it. Isn't this pseudoscience?? Link to comment Share on other sites More sharing options...
5614 Posted November 1, 2005 Share Posted November 1, 2005 Isn't this pseudoscience?? Yes! It is not darkness rays but more the absence of light. The shadow is caused because the object is blocking some of the light from reaching the spot behind the object, resulting in a darker area relative to that surrounding the object, this is a shadow. Dunno what you teacher is on about! Link to comment Share on other sites More sharing options...
RyanJ Posted November 1, 2005 Share Posted November 1, 2005 Yes! It is not darkness rays but more the absence of light. The shadow is caused because the object is blocking some of the light from reaching the spot behind the object' date=' resulting in a darker area relative to that surrounding the object, this is a shadow. Dunno what you teacher is on about![/quote'] Actually how about this: There is a thing called dark matter and so too there is also something called dark energy. In a way it can be considered to be bark light because it can't be seen directly... could your teacher have meant that? If there is such a thing then thats the closest I can think of... maybe you should have posted this in the Physics section to see if anyone else there agrees (hopefully the physics experts will see this post and reply) Cheers, Ryan Jones Link to comment Share on other sites More sharing options...
CanadaAotS Posted November 2, 2005 Share Posted November 2, 2005 Unless the matter your speaking about is anti-matter, there would be no photons (or in this case anti-photons) to be emitted as "dark light". Darkness is just the absense of photons being relfected to your eye from that direction. So as 5614 said, it'd just be a shadow lol. Link to comment Share on other sites More sharing options...
Glider Posted November 2, 2005 Share Posted November 2, 2005 Maybe he's just assessing how awake his class is by seeing how many just sit there going "Ooooohh, really?" and how many go "Wait a minute! That's plain madness!" I do it myself sometimes; slip some obviously and wildly wrong thing into the lesson and see how many go "Uhuh, yep, ok." After all, I'm not just providing information, I'm supposed to be teaching them to think critically. I always point it out if it slips by though. I never let them go away believing it. Link to comment Share on other sites More sharing options...
swansont Posted November 2, 2005 Share Posted November 2, 2005 Unless the matter your speaking about is anti-matter' date=' there would be no photons (or in this case anti-photons) to be emitted as "dark light". Darkness is just the absense of photons being relfected to your eye from that direction.[/quote'] Photons are their own antiparticle. Antiphotons are not darkness, and antimatter would give off light like matter does. Link to comment Share on other sites More sharing options...
RyanJ Posted November 2, 2005 Share Posted November 2, 2005 Photons are their own antiparticle. Antiphotons are not darkness, and antimatter would give off light like matter does. Does that mean Photons and antiphotons are basically the same jsut opposite? Oh I have one question on that point: Do all particles 9Includin the boson force transmitters) have anti-particles? If yes then can there be an anti-graviton? Cheers, Ryan Jones Link to comment Share on other sites More sharing options...
5614 Posted November 2, 2005 Share Posted November 2, 2005 It means photons and "antiphotons" would be the same thing if they both existed. "antiphotons" don't exist in that they're in everyway identical to photons, it'd be like having 2 words for the same thing. The photon is it's own antiparticle. ie. photon = antiphoton they're the same thing. Link to comment Share on other sites More sharing options...
RyanJ Posted November 2, 2005 Share Posted November 2, 2005 It means photons and "antiphotons" would be the same thing if they both existed. "antiphotons" don't exist in that they're in everyway identical to photons' date=' it'd be like having 2 words for the same thing. The photon is it's own antiparticle. ie. photon = antiphoton they're the same thing.[/quote'] Woo I was right for once then I was thinking about this today in school... Because of the wave-particle duality can you only tell a photon from an antiphoton when they are in particle state? When its in a wave form would they be both identical? Cheers, Ryan Jones Link to comment Share on other sites More sharing options...
5614 Posted November 2, 2005 Share Posted November 2, 2005 A photon is it's own antiparticle... regardless of whether you view it as a wave or a particle. An antiparticle is defined as the particle reversed in all ways. It is going backwards in time, has opposite charge & opposite spin. So an electron going back in time is a positron. This only applies to charged particles. This includes Leptonic charge for particles such as neutrinos. So photons have no charge and so when they go back in time they you get the same particle with opposite spin. This is still a photon. So we say a photon is it's own anitparticle This also ties in nicely with the fact that time doesn't really exist to a photon (seeing as it's travelling at c) so a photon doesn't know whether it's going back or forwards in time... so it's just as well it doesn't make a difference! ^ Above should answer your thing about anti-graviton. [edit] just to make one thing clear. You are not reversing the charge/spin as part of the "working out antiparticles" all you are actually doing is reversing its time, this time reversal changes the spin/charge. It's all about the time reversal. Link to comment Share on other sites More sharing options...
CanadaAotS Posted November 2, 2005 Share Posted November 2, 2005 Photons are their own antiparticle. Antiphotons are not darkness, and antimatter would give off light like matter does. I wasn't imply that antimatter gave off dark light, just that maybe that was what his teacher was implying... Also, would say an antimatter sun give off regular photons then? And if it gave off normal photons would its gravity be normal too (as opposed to "antigravity" thats supposed to repel normal matter)? I've always wondered if there is a such thing as antigravity / gravitons... Link to comment Share on other sites More sharing options...
CanadaAotS Posted November 2, 2005 Share Posted November 2, 2005 Oh alright nvm then it'd be the same for the graviton as it (is supposed to?) travels at the speed of light as well and has no charge the antigraviton would be the exact same so it'd be its own antiparticle just like photons... Link to comment Share on other sites More sharing options...
5614 Posted November 2, 2005 Share Posted November 2, 2005 Antimatter gives off regular photons. Antimatter has normal gravity. Gravitons quite possibly exist, although have never been experimentally proven or observed. From a scientist's point of view antigravity does not exist... but lets not go too into that, start a new thread if anyone wants an antigrav argument. Link to comment Share on other sites More sharing options...
RyanJ Posted November 2, 2005 Share Posted November 2, 2005 From a scientist's point of view antigravity does not exist... but lets not go too into that' date=' start a new thread if anyone wants an antigrav argument.[/quote'] Good idea for a thread - posted one here: http://www.scienceforums.net/forums/showthread.php?goto=newpost&t=16005 I'm interested in heraing both sides of the argument if there are any Cheers, Ryan Jones Link to comment Share on other sites More sharing options...
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