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Can a Human See a Single Photon? (1996)

math.ucr.edu

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Re: Can a Human See a Single Photon? (1996)

#101

Post by yetanotherloser »

thesimonlee wrote: post #99
eternauta3k wrote: post #90

Earlier quoted context omitted.

Does an infrared photon have enough energy to stimulate a rod?

Definitely. 20 years ago when homes were not littered with LEDs all over, I would wake in the night to total blackness. I could still find my way around the house just able to see based on what is I suppose a noise floor of ambient temperature. Go into the kitchen & behold the stove top emitting 'bright' white light, from I suppose a temperature of around 30degC /90F. Obviously everything is a blackbody, but those ph…

Gosh. I used to have pretty good night vision and recognise what you mean about "see based on the noise floor" - but I never had an experience like seeing the stovetop heat. Remarkable. I wonder how much variation there is between people? Unfortunately mine's faded with age so I don't think it's worth my trying to see if I can see that myself now...

Re: Can a Human See a Single Photon? (1996)

#102

Post by dylan604 »

ASalazarMX wrote: post #97
de6u99er wrote: post #84

Earlier quoted context omitted.

What if the room was made out of perfect mirrors?

It's still more likely to be reabsorbed by other part of the body than the other's retinas. Wonder if anyone will dare to do the math.

>Wonder if anyone will dare to do the math.

Warning! Madness this way lies.

I'm thinking back to the movie Real Genius during one of the montage scenes where they're cramming for finals in a common area when one student just stands up from his material and starts screaming in madness before fleeing. Everyone else, just behaves as if this is normal as someone takes the now vacant place at the table.

That guy screaming in madness? That's me after just thinking of doing the math without even grabbing a pencil.

Re: Can a Human See a Single Photon? (1996)

#103

Post by [deleted] »

mlindner wrote: post #55
LastTrain wrote: post #45

Earlier quoted context omitted.

It is too bad the risks (criminal) are so high, LSD is an interesting enough experience that is worth trying at least once.

As someone who's never taken LSD and have talked to people who have, the number of times people express irreversible changes in how they think about things just from trying things once makes me think that it is not a very good idea to even try once. A chemical that causes irreversible random brain chemistry changes from a single use sounds like damage has happened and the user simply interprets that damage as an impr…

[deleted]

Re: Can a Human See a Single Photon? (1996)

#104

Post by asah »

mlindner wrote: post #55
LastTrain wrote: post #45

Earlier quoted context omitted.

It is too bad the risks (criminal) are so high, LSD is an interesting enough experience that is worth trying at least once.

As someone who's never taken LSD and have talked to people who have, the number of times people express irreversible changes in how they think about things just from trying things once makes me think that it is not a very good idea to even try once. A chemical that causes irreversible random brain chemistry changes from a single use sounds like damage has happened and the user simply interprets that damage as an impr…

...or the opposite.

the VAST majority of people who have taken LSD under reasonable circumstances have an incredible, life changing experience.

I personally know 100s who have, not a single one of them regrets it.

Re: Can a Human See a Single Photon? (1996)

#105

Post by monktastic1 »

yamtaddle wrote: post #91
phailhaus wrote: post #51

Earlier quoted context omitted.

Yep! Any interaction counts. If something interacts with a photon, and that interaction can only happen if it goes through one of the two slits (i.e., it tells you "which way" the photon went), then the interference pattern will disappear.

What escapes my understanding with the whole "interaction is observation" thing is that I don't get how anything could ever not be interacting with a whole lot of other stuff. Gravity and EM fields are everywhere. Even if photons are somehow immune to that (which, they're not, because gravity can re-direct photons) it's my understanding that we can see the same interference patterns with particle streams of ordinary…

The short answer (as I understand it) is that decoherence is not binary. The gravitational field may be able to partially resolve the position, for example, and so you only get slight reduction in interference.

https://physics.stackexchange.com/questions/34993/reversing-...

Re: Can a Human See a Single Photon? (1996)

#106

Post by xhrpost »

lebubule wrote: post #15

Recent experiments have put the claim to test Overview https://www.nature.com/articles/nature.2016.20282 The actual work https://www.nature.com/articles/ncomms12172 > Here we report that humans can detect a single-photon incident on the cornea with a probability significantly above chance.

> To optimize this ratio in practice, we used the multi-pixel sensor of an electron multiplying charge-coupled device (EMCCD) camera as our idler detector (Fig. 1a). As the EMCCD can detect multiple photons simultaneously, it allowed us to identify and reject, that is, post-select, all events other than those where a single-photon pair was generated with a higher efficiency than with more traditional single-photon avalanche diodes (SPAD)

How is it possible to both detect a photon and then allow it to travel to the human eye? Wouldn't detection require absorption of the photon?

Re: Can a Human See a Single Photon? (1996)

#107

Post by mrguyorama »

asah wrote: post #104
mlindner wrote: post #55

Earlier quoted context omitted.

As someone who's never taken LSD and have talked to people who have, the number of times people express irreversible changes in how they think about things just from trying things once makes me think that it is not a very good idea to even try once. A chemical that causes irreversible random brain chemistry changes from a single use sounds like damage has happened and the user simply interprets that damage as an impr…

...or the opposite. the VAST majority of people who have taken LSD under reasonable circumstances have an incredible, life changing experience. I personally know 100s who have, not a single one of them regrets it.

The big problem for me is that everyone I know who has done psychedelics and enjoyed it says "yeah it was fun, not a big deal" while the people who have bad trips have REALLY FUCKING BAD TRIPS. The upside doesn't seem that big, and the downside is possibly going insane for a few years like someone I know of. It's an extremely small chance and you basically have to be predisposed and making poor choices about your setting, but it's still there.

Re: Can a Human See a Single Photon? (1996)

#108

Post by mrguyorama »

wyager wrote: post #50
vjulian wrote: post #40

Genuine question: I’ve never taken LSD, but could some of its purported visual effects be explained as seeing photons via a depressed neurological filter?

No, eliminating the photon count filter would just make your vision look noisy/staticky in dark conditions. Most of the effects of LSD (patterns etc) are actually pretty well understood. It's probably caused by a stable geometric pattern generated by a reaction-diffusion process in your visual cortex. https://plus.maths.org/content/uncoiling-spiral-maths-and-ha... Related to your question (although minus drugs) - I v…

In the dark I perceive an extremely "noisy" visual field, with lots of different color dots like on a shitty camera sensor at low light. Is that not normal?

Re: Can a Human See a Single Photon? (1996)

#109

Post by mecsred »

xhrpost wrote: post #106
lebubule wrote: post #15

Recent experiments have put the claim to test Overview https://www.nature.com/articles/nature.2016.20282 The actual work https://www.nature.com/articles/ncomms12172 > Here we report that humans can detect a single-photon incident on the cornea with a probability significantly above chance.

> To optimize this ratio in practice, we used the multi-pixel sensor of an electron multiplying charge-coupled device (EMCCD) camera as our idler detector (Fig. 1a). As the EMCCD can detect multiple photons simultaneously, it allowed us to identify and reject, that is, post-select, all events other than those where a single-photon pair was generated with a higher efficiency than with more traditional single-photon av…

"SPDC is a quantum optical technique in which correlated pairs of photons (called signal and idler) are produced probabilistically from a higher energetic pump photon in a non-linear crystal following energy and momentum conservation16,17 (Fig. 1a). By detecting one of the photons (idler) and sending the other (signal) to the observer’s eye..." I suppose conservation of momentum allows them to guarantee pairs, in which case a photon in one direction guarantees a photon in the opposite direction.

Re: Can a Human See a Single Photon? (1996)

#110

Post by HPsquared »

d_tr wrote: post #49
mensetmanusman wrote: post #38

Earlier quoted context omitted.

Would be fun to see if it’s possible to set up the experiment as a double slit. Would humans sense an interference pattern? Is the back of an eye a sufficient observer? :)

> Is the back of an eye a sufficient observer? :) It definitely is. The retina "measures" photon positions, which is why you see images. Observation is just interaction, no need to consider whether A can observe B. If they interact, some kind of observation takes place.

When the photon passes through the lens and the watery liquid part, its path is bent by refraction.

Does that process also count as an "interaction", or is that different to what happens when the photon hits the retina?

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