Can you see IR?

Can you see the red light?


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    34

DaveC426913

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I learned https://www.physicsforums.com/showthread.php?p=1098513&posted=1#post1098513" that some people are sensitive to lower frequency light than others. In fact, some people can see well into the infra-red range.

I was very skeptical, so I tested it out. I was right, I cannot see IR. However, to my astonishment, my son can!

Here is my experiment, which I encourage you to try. I'd love to know.

1] Get really dark - throw a heavy blanket over your head or go into a dark room.
2] Point your remote at your face. Press some buttons. Note if you see the red light or not.
3] (the enhanced-assisted version) To ensure you're not fooling yourself - have someone else press the buttons so you can't anticipate on-ness or off-ity.
 
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JasonRox

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I shall try that out one day.

I doubt I can see it though.
 
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I can't, I've tried before...although it wasnt a perfectly dark environment...
 

Gokul43201

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Do all remote controls use the same LED? A 50 nm shift in the emission spectrum can make the difference between "Eureka, I see it!" and "Ugh, can't see squat!"
 
R

Rach3

If it's too dim, try pointing a 50W infrared laser directly into your eye. You might be able to detect that.
 

DaveC426913

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Gokul43201 said:
Do all remote controls use the same LED? A 50 nm shift in the emission spectrum can make the difference between "Eureka, I see it!" and "Ugh, can't see squat!"
Yeah. this is the big flaw in my experiment.

However, I have demonstrated to my satisfaction that the phenom is real since my own experimentation used the same remote. Of four people in my house, three could not see it, while one could.
 
R

Rach3

DaveC426913 said:
Of four people in my house, three could not see it, while one could.
How sure are you? Are there any other (visible) lights on the remote? Was the experiment controlled against dishonesty?
 
of course I can
 
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I don't think I can. I tried an experment in my bathroom and I couldn't see anything but there was some light comming form the door, so I might try again in my garge.

I wonder if it's possible to get to train your eyes to see infrared(It just would be cool to se infrared light)?
 

NoTime

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Gokul43201 said:
Do all remote controls use the same LED? A 50 nm shift in the emission spectrum can make the difference between "Eureka, I see it!" and "Ugh, can't see squat!"
Some are fairly bright, and can be seen in dim lighting.
Others are extremely dim and it has to be dark to see them.
Don't know if it's power or wavelength that makes the difference. Perhaps both.

The one out of 10 I can't see probaby has almost dead batteries, since its gotten real picky about pointing.
Maybe I'll find some new ones and try it again.
 

NoTime

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DaveC426913 said:
I was very skeptical, so I tested it out. I was right, I cannot see IR. However, to my astonishment, my son can!
Well that's one :smile:
 

DaveC426913

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Rach3 said:
How sure are you? Are there any other (visible) lights on the remote? Was the experiment controlled against dishonesty?
I made sure. I did the experiment a second time after ensuring I'd controlled it specifically against dishonesty.

No other visible lights.
I ensured it was pitch dark.
I held the remote and pressed the button rapidly and randomly.

Every time, he immediately said 'on' or 'off' - he didn't even have the decency to be hesitant :grumpy: :grumpy: . He got it right no matter how many times I tried it or how fast I did it. In fact, we went under the blanket together and I did the experiment. He still got it right every time, and yet I could see nothing. Once we took the blanket off, he showed me where the LED was situated within the little window.
 
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Math Is Hard

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I definitely see it. It is faint, but clearly there.
 

Danger

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Totally expecting failure, I took the remote for the TV into the bathroom just now and the damned thing was bright as day (okay, not quite). W asked me what I was doing, so I pointed it at her and asked if she could see the light. This was in the living room with the TV, the kitchen light, and the neighbourhood lights coming through the balcony doors. She saw it fine, so I turned it around and saw it quite plainly even in that ambient light. :bugeye:
MUTANTS, UNITE!
 
One of my remotes has a red 'signal on' light that goes on in addition to the IR emittin bulb. I could see this 'signal on' light in the back ground of the IR bulb, so I say beware of your remote and double check it. My other remote had no 'signal on' light and I could see the IR in light out conditions.

Dave, I suggest blacking out your kitchen, turning on your stove element, standing beside your son and seeing the difference in your IR threshold. Your son would beat you by a few seconds I'd guess. If you were especially into it, you could get a hold of your stove's specs and derive a solution for how long a second of delayed observation equals in terms of element temperature and finally of the wavelength emitted.

I think my element goes from 0 to 10 (max) in about 90 seconds. At 10 the element appears to be a orangy-red (more orange than red). I'm guessing its temperature at 10 is ~800C. At a setting of 0 (off), the element is roughly room temperature 20C. I'm not sure what material it is which would be critical to calucating its heating curve.

Anyways, just a thought.
 

DaveC426913

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Chaos' lil bro Order said:
One of my remotes has a red 'signal on' light that goes on in addition to the IR emittin bulb. I could see this 'signal on' light in the back ground of the IR bulb, so I say beware of your remote and double check it. My other remote had no 'signal on' light and I could see the IR in light out conditions.
Yup. Same here. I used the non-cheating one.

Chaos' lil bro Order said:
Dave, I suggest blacking out your kitchen, turning on your stove element, standing beside your son and seeing the difference in your IR threshold. Your son would beat you by a few seconds I'd guess. If you were especially into it, you could get a hold of your stove's specs and derive a solution for how long a second of delayed observation equals in terms of element temperature and finally of the wavelength emitted.
Yeah that's a pretty iffy way of doing it though. Very prone to "overanticipation" and even "cheating". I also doubt it would be slow enough to observe much difference between us that wouldn't be swamped by reaction and perception times.

If he says "now" and I sat "now" two seconds apart, is that pretty much the same time or is that a significant difference?
 
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DaveC426913 said:
Yeah that's a pretty iffy way of doing it though. Very prone to "overanticipation" and even "cheating". I also doubt it would be slow enough to observe much difference between us that wouldn't be swamped by reaction and perception times.

If he says "now" and I sat "now" two seconds apart, is that pretty much the same time or is that a significant difference?
Just for the hell of it, try having your son adjust the heat control to the point where the light first becomes visible to him. Mark it. Then, do this yourself, and see if there is any noticable difference between the marks.
 

NoTime

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Stove controllers tend to have a very large hysterisis.
It would be very dificult to control for any selected point at best.
 
R

Rach3

Too many variables. Blackbodies emit at all frequencies - in essence you'd only be finding out who can see the dimmest red (visible) light.

Minor complaint - all visible light is visible; infrared radiation is invisible by its defintion. There is no "cutoff wavelength" or anything. If however, you can see all the way down to 10-micron light, then that's very different; then you have career potential as a spectrometer.
 
zoobyshoe said:
Just for the hell of it, try having your son adjust the heat control to the point where the light first becomes visible to him. Mark it. Then, do this yourself, and see if there is any noticable difference between the marks.
In all ovens I've seen the heating body is either turned on full power or off, according to the thermostat's setting and temperature. I'm not sure your suggestion would work, as with the door open any set temperature will have the heating body powered on indefinitely.
 
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Yonoz said:
In all ovens I've seen the heating body is either turned on full power or off, according to the thermostat's setting and temperature. I'm not sure your suggestion would work, as with the door open any set temperature will have the heating body powered on indefinitely.
Not the oven element, the stove elements. These definitely are variable. You can set them to anything from low, slow simmer to fast boil.
 

DaveC426913

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NoTime said:
Stove controllers tend to have a very large hysterisis.
It would be very dificult to control for any selected point at best.
I have known a few stove controllers, and frankly, they are pretty even-tempered.
:biggrin:
 

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