Light, that is slower than light.

[Slash]

Here I am, on another 3:30 am morning, laying in bed, not being able to fall asleep. I just had one of those times when I get caught up in deep thought and this came across my mind.

Now before continuing those who I've talked to have said I must be crazy.

Is it possible under some circumstances, for light to travel substantially slower than normal?

Reason I ask is because I think I have witnessed this event many times over the years and never really piped up because no one has believed me.

For example, I turn on a light in my bedroom. I can physically see the light travel to the other side of the room. In other words, it takes about 1/4 of a second, maybe just slightly less than that, to travel from the light source to the dark portion of the room. 0.25 would be closest I'd guess.

Is there a phenomena that this can be called that I am unaware of? Is it some sort of pollution, say glass, that is slow it's decent?

Light travels at around 186,000 miles a second. What I'm witnessing (this does not happen all the time either), is light that (I'm not a math whiz, bear with me) is substantailly slower but fast enough that one couldn't capture this on film the way my eyes see it. Maybe with something very very very high tech.

I'm just dazzled that no one beleives me and everyone thinks I'm nuts, and I can clearly see this happening before my eyes.

Is it possible my eyes are taking some strange twist on adjusting from darkness to light in certain situations? I noticed this tends to happen more or less around that point when I can clearly see the light taking it's time.

Just wondernig if anyone knows what I'm experiencing or can back me up and say you've witnessed this as well.

EDIT:

It's just pccured to me that the same thing can happen when the light source is shut down, when the light is absorbed into the surrounding, it takes just as long as what I was just talking about. I can actually see it dissapate.

 

[Aquarelle]

Light has been recorded travelling as slow as 30 miles an hour. So, in theory; yes?

 

[Third Reign]

Search up something called Electromagnetically Induced Transparency (EIT). With this technique Scientists have been able to slow light from its usual 3x10^8 m/s to a mere 17 m/s. The light pulse sent through this medium was observed with a high speed camera.

To add a bit of common knowledge as well: Light slows in every medium it passes through when compared to vacuum. The whole concept of refractive indices is based on this and the reason why light travels at an angle when going from one medium to another. The change in speed is very insignificant thought to what you look for.

In electromagnetic theory, light travels the slowest when dispersive properties are very steep (derivative of dispersion is large). The trouble is that at the point of steepest dispersion most media also have great absorption of light. Slow light cant be observed in this case. That's why EIT has to be used, It manipulates atoms with a certain configuration of energy states (two lower, one upper state, called lambda states) into a so called dark state, where the absorption of light is prevented and thus the dispersive properties can be observed.

For my credibility: I'm a physicist in the field of quantum optics.

As for your phenomenon, it's very likely your eyes adjusting to the brightness of what you're looking at. Tired eyes take quite a lot longer to adjust.

 

[Mike Rotch]

In other words, it takes about 1/4 of a second, maybe just slightly less than that, to travel from the light source to the dark portion of the room. 0.25 would be closest I'd guess.

Light travels at around 186,000 miles a second.

0.25 seconds.

Or close to 3.3 nanoseconds (0.000000003).

Depending on your maths.

👍

 

[dhandeh]

Is it possible under some circumstances, for light to travel substantially slower than normal? ...

For example, I turn on a light in my bedroom. I can physically see the light travel to the other side of the room.

Search up something called Electromagnetically Induced Transparency (EIT). With this technique Scientists have been able to slow light from its usual 3x10^8 m/s to a mere 17 m/s. The light pulse sent through this medium was observed with a high speed camera.

To add a bit of common knowledge as well: Light slows in every medium it passes through when compared to vacuum. The whole concept of refractive indices is based on this and the reason why light travels at an angle when going from one medium to another. The change in speed is very insignificant thought to what you look for.

Going by this reply, unless your bedroom is in a black hole, you probably can't see the light actually moving. Unless your name is Neo.

 

[axletramp]

Unless your room is a few thousand kilometres across I'd suspect it was more to do with your eyes reacting to the flood of light and giving you the impression of a gradual illumination. I would suspect there was more at play here rather than the speed of light changing, like a variation in the reflective levels of the paint on the walls and other objects in the room, even the bulbs themselves. Do you have energy bulbs installed?

 

[daan]

You must have got one of those cheap Walmart bulbs. They can't afford to use proper light as they would be more expensive so they use some kind of synthesised light that travels slower than normal light.

 

[Wolfe]

^ Walmart must put the more expensive light into their plant-growing bulbs. My fiancée bought one for $6 and the light was so fast the bulb burned through all of it in a day.

 

[Encyclopedia]

Light travels a bit slower through water I believe.

 

[Dean]

The speed of light is exactly 299792458 meters/second in a vacuum. Divided with the index of refraction of water (1.33) should give ~225407863 meters/second. So technically, yes, light travels slower through water.

 

[dhandeh]

So, he lives in Atlantis then?

 

[Wiegert]

Light has been recorded travelling as slow as 30 miles an hour. So, in theory; yes?

I think there was a case where they brought light to a virtual standstill by passing it through a gas of sodium atoms cooled to almost absolute zero, which is the same way they slowed it down to 30/40mph.

 

[wfooshee]

Is the refrigerator dark for half a second or so when you open it?

Seriously, there is no phenomenon you could live through that would make the light take a perceptible amount of time to cross the room. However, a quarter of a second sounds about right for pupil reaction time in your eyeballs.

 

[Slash]

Do you have energy bulbs installed?

At the moment yes, but I've seen it also happen with a TV, standard bulbs etc.

You must have got one of those cheap Walmart bulbs.

Home Depot, if you want to get specific =P

Is the refrigerator dark for half a second or so when you open it?

Seriously, there is no phenomenon you could live through that would make the light take a perceptible amount of time to cross the room. However, a quarter of a second sounds about right for pupil reaction time in your eyeballs.

This must be what's happening then.

 

[David]

This isn't really to do with slowing light down, but it is a video about a new technique of capturing the movement of light with special camera systems.

http://www.ted.com/talks/ramesh_raskar_a_camera_that_takes_one_trillion_frames_per_second.html

Also, it's freaking awesome.

 

[Omnis]

The physics are normal. Your amacrine and horizontal cells are totally wacked though.

 

[Famine]

Reason I ask is because I think I have witnessed this event many times over the years and never really piped up because no one has believed me.

For example, I turn on a light in my bedroom. I can physically see the light travel to the other side of the room. In other words, it takes about 1/4 of a second, maybe just slightly less than that, to travel from the light source to the dark portion of the room. 0.25 would be closest I'd guess.

Thus proving Dark Sucker Theory!

 

[Slash]

Thus proving Dark Sucker Theory!

How do people think of this stuff

 

[Omnis]

Thus proving Dark Sucker Theory!

This one?

Electric bulbs don't
emit light; they suck dark.

 

[MonGnoM]

i've heard that some physic guys slowed light down to ~ 15 mph...
that was a special experiment where they shoot a light beam through a cloud of a special material...