light

Hello all. Last night i was sitting at my window and looked at the stars. Late at night i (maby) saw something that i don't know what is. It looked like a flash from around a star in the big dipper, however, i can't figure out what it was if it was anything at all and not just my mind playing...

http://www.technologyreview.com/blog/arxiv/26992/ I am really confused by the above article. From a brief read through, they're saying that by slowing down light and then speeding it back up, we can effectively hide something in time for about 110 nanoseconds. Is this correct? Does that mean...

A laser in space fires one second long beams of light at one second intervals. You are 10 light seconds away from the laser and you receive the beams of light 10 seconds after they were emitted and measure them to be one second long with one second intervals. You then travel toward the laser at...

In the thread about the Chinese building collapse, GreyICE posted this which linked to a "HowStuffWorks" article. That article mentioned a putative reason for glass' transparency having to do with atomic/molecular "looseness" and further linked to another HSW article. The article spoke of the...

There have been many strange physics claims made by "single topic", obsessive, fight-picking, drive-by posters in the time I have been observing here, and most seem to be quickly dispatched by the many knowledgeable members here. Recently, there were two that I am not sure were directly...

So very, very silly. :) Apparently the creator of this YouTube video had a friend who worked out that by using a particle detector or Geiger-counter to trigger a random character generator he could communicate directly with God. He admits that he never actually saw the device, and the friend...

This seems like a simple question but is it? We all know that the speed of light is about 300,000 km/s (186,000 mi/s) in a vacuum and that this applies to all other electromagnetic waves too. We also know that this figure is reduced when travelling through air, water, glass, etc. It is often...

Please note from the start of this that my knowledge on this subject is limited, hence the asking for clarification. To my understanding this is how light works. Light is emitted from a source, (sun, lightbulb, etc.), and either travels to your eye, or reflects off an object and into your eye...

Can anyone explain this - I don't know what is happening. http://www.youtube.com/watch?v=mgVxSu8XBqw I have just uploaded a video on youtube showing a little experiment I was doing. I made a circuit using lots of metal objects and put a high voltage (personal safety device - 50,000V?) through...

Is there something fundamentally different between artificial light, in its general and broadest sense, and natural light, or is light simply ... well, light?

This question came up, in all things, during a Philosophy lesson I was in earlier today. We were discussing the nature of immaterial substances (i.e. Substances without mass) and how they couldn't affect the world. This was in relation to Mind/Body duality, specifically the 'Mind'. Anyway, I was...

I'm currently teaching myself basic physics, and a strange thought occured to me while I was casually looking ahead in my textbook this afternoon. Please forgive me if what follows is a bit simplistic. I haven't studied the chapters on light yet! Okay, here goes ... If light passes by at a...

If uniformly expanding space stretches light then it should stretch it uniformly (equally in all directions). The overall shape of a uniformly stretched light wave would remain essentially the same but larger. As it wouldn’t actually be stretched as a shape, how can it be redshifted? ETA - If...

At this stage, my vote is no.

I've seen photographs of nebula that do not appear to have stars. I presume it is because there is not enough mass in the nebula to form stars. My question is, how are these nebula emitting light? I presume the light is coming from ionized gas, but where is the energy coming from to ionize...

I thought this was interesting. Does anyone know anymore about this? Are there any botanists who might be able to shed more light, so to speak, regarding this? /I am sorry if this has already been posted.

Okay, I apologize in advance for asking what must be a rather obvious question to everyone out there, but... Suppose that the age of the universe is 14BY and the most distant object we can see is 13B lightyears away (I picked these because they seem to be close to the actual values while still...

Question One - Various answers have been given, as to why Gravity is able to excape from a black hole - but none have addressed the fact that gravity has now been shown to travel at speed c. Question Two At speed c, time has dilated to zero - Therefore, from light's frame of reference...

Hello everybody, Just a few questions that are on my mind. 1) If something is travelling faster than sound, is it correct to say that an observer towards whom the object is travelling will see it closing in in complete silence (barring any ambiant noise, of course)? If so, at which point...

I came across this article that, if I understand it correctly, rather boggles my mind. Apparently Harvard researchers were able to demonstrate that by passing a light through a supercooled sodium vapor cloud (at temperatures close to absolue zero) the light separated into two different states...

Please remember that this is all just brainstorming. I’ve been trying to imagine how light travels and have come up with this bizarre theory . . . Imagine that light somehow travels by way of universal carriers. Lets give these carriers a cute name and call them “Blips” Blips exist everywhere...

Now I found this offer a bit dubious. But what say you, a genuinely working product or example of weird woo? I'm particularly wondering about that Energy Bar thing and am left wondering about their definition of "energy" Maybe Randi should invite Philips to apply for the million dollar price...

I see the light! I see it! Ouch! Stop already. Bummer. The Lord giveth and The Lord taketh away.

My question is simple: What are the major differences between the photons emmited by the sun and those emmited by say a lamp? I know that if you go outside and place a magnifying lens over say a small stack of dried leaves, you can set them on fire by focusing the rays into one point on the...

Bob Nixon from Australian Skeptics investigates a cross of light. http://www.youtube.com/watch?v=63ZRFhDvyHY

If I shine a flashlight up into the night sky, where does the light go? I am guessing that it will keep going forever, but will become diffused since it will spread out from the source in a conical shape. Is this correct?

I once asked a philosophy professor “What is philosophy about?” He said philosophy is “radically critical self-consciousness”. This was 35 years ago. Only in the last five years have I begun to understand that statement I took a number of courses in philosophy three decades ago but it was not...

http://www.msnbc.msn.com/id/14894187/ I found this very interesting. With more research perhaps we can finally start to understand why people claim to have the experiences that they do. It makes a lot of sense, no?

A Republican congressman (Curt Weldon, vice chairman of the House Armed Services Committee) has publicly praised an anti-Bush video. And not just any anti-Bush video, but the one by BYU physics professor Steven E. Jones which accuses the Bush administration of deliberately allowing 9/11 to...

Has anyone heard of this? http://thelightball.th.funpic.de/viewtopic.php?t=4&sid=0e050c110ac1a89cee494c3ce57ebe38 Stumbled on it today and wondered if it has been covered here before.