Naked Science Forum

On the Lighter Side => That CAN'T be true! => Topic started by: Emilio Romero on 13/05/2009 18:20:59

Title: when we shut off the light in a room, what is the "speed" of darkness?
Post by: Emilio Romero on 13/05/2009 18:20:59: Ok, it gets dark pretty fast.... [;D]
Title: when we shut off the light in a room, what is the "speed" of darkness?
Post by: Ethos on 14/05/2009 00:12:33: Quote from: Emilio Romero on 13/05/2009 18:20:59
Ok, it gets dark pretty fast.... [;D]
One unit of Plank time.............5.39124X10^-44 seconds

Nothing is darker than the mind of the suspicious.............Ethos
Title: when we shut off the light in a room, what is the "speed" of darkness?
Post by: Emilio Romero on 14/05/2009 01:18:34: so, there is a speed of light, of darkness, of sound and silence...
[:D] [:D] [::)]
Title: when we shut off the light in a room, what is the "speed" of darkness?
Post by: Don_1 on 14/05/2009 10:18:00: ..... and the UK government have set up speed cameras for the lot!!!
Title: when we shut off the light in a room, what is the "speed" of darkness?
Post by: Fortran on 14/05/2009 17:40:08: I measured the speed of darkness last night, it was light for about an hour and a quarter after the sun went down so I estimate the speed of sdarkness to be around 34mph.
Title: when we shut off the light in a room, what is the "speed" of darkness?
Post by: Emilio Romero on 15/05/2009 00:29:51: great !!
[:D] [:D] [:D]
Title: when we shut off the light in a room, what is the "speed" of darkness?
Post by: LeeE on 15/05/2009 16:37:46: It depends upon the type of light that is being switched off.

An incandescent light bulb doesn't cool instantly and if you're not looking directly at the bulb when it's switched off it is sometimes possible to detect that the dimming of the room takes a small but perceptible period of time.

I've also noticed that one of my energy-saver bulbs sometimes flashes quite brightly a few times after it has been switched off. I suspect this is due to stored charge in the bulb electronics, but I'm not sure about that - there appears to be no faults in the switch and I am happy that it is isolated when the flashes occur.
Title: when we shut off the light in a room, what is the "speed" of darkness?
Post by: Fortran on 15/05/2009 18:15:16: Ok time to put you all out of your misery, the speed of 'dark is the same as the speed of light. If the sun instantly dissappeared it would take some 8 min 20 secs before the last (direct) light (from the sun) hit the earth
Title: when we shut off the light in a room, what is the "speed" of darkness?
Post by: Emilio Romero on 15/05/2009 20:58:38: thus the speed of silence is the same as the speed of sound... [;D]
Title: when we shut off the light in a room, what is the "speed" of darkness?
Post by: Fortran on 15/05/2009 21:18:28: Quote from: Emilio Romero on 15/05/2009 20:58:38
thus the speed of silence is the same as the speed of sound... [;D]
No, it took you a whole 2 hours for you to shut up! lol!
Title: when we shut off the light in a room, what is the "speed" of darkness?
Post by: Emilio Romero on 16/05/2009 01:41:52: touché... :)
Title: when we shut off the light in a room, what is the "speed" of darkness?
Post by: Yomi on 07/06/2009 20:29:23: speed of darkness is same as speed of light
Title: when we shut off the light in a room, what is the "speed" of darkness?
Post by: scalyblue on 30/08/2009 09:03:20: Darkness is the absence of light; since it doesn't exist, it can't have a speed. The light will stop radiating out of the bulb and traverse the room at the speed of light until it hits something, that reflected light will go to your retina to be processed into visual imagry

If you really want to be pendantic about it, your perception of the darkness happens at half the speed of light, plus the response time of your visual cortex.