# Do photons exist?
**URL:** https://boards.straightdope.com/t/do-photons-exist/554215
**Category:** Factual Questions
**Created:** [September 18, 2010, 8:27pm UTC](https://boards.straightdope.com/t/do-photons-exist/554215 "2010-09-18T20:27:52Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@The\_Hamster\_King](https://boards.straightdope.com/u/The_Hamster_King)
#### Post date: [September 18, 2010, 8:27pm UTC](https://boards.straightdope.com/t/do-photons-exist/554215/1 "2010-09-18T20:27:52Z")
From the reference frame of the photon, its trip from A to B takes zero time and covers zero distance. So wouldn’t it make more sense to think of emission/transmission/absorption as a single instantaneous event between two particles that are adjacent to each other? And to think of the apparent passage of a photon between them as merely a useful fiction for describing that event in other reference frames?
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### Author:  [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)
#### Post date: [September 18, 2010, 9:08pm UTC](https://boards.straightdope.com/t/do-photons-exist/554215/2 "2010-09-18T21:08:39Z")
One point is that they bend in a gravitational field. Also if photons don’t exist what is a laser doing?
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### Author:  [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)
#### Post date: [September 19, 2010, 12:18am UTC](https://boards.straightdope.com/t/do-photons-exist/554215/3 "2010-09-19T00:18:01Z")
But if you consider only the reference frame of a photon and no other, aren’t you creating a privileged reference frame?
Once you consider all reference frames, your problem goes away.
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### Author:  [@Khadaji](https://boards.straightdope.com/u/Khadaji)
#### Post date: [September 19, 2010, 12:31am UTC](https://boards.straightdope.com/t/do-photons-exist/554215/4 "2010-09-19T00:31:40Z")
If they don’t exist, where do Photon torpedoes come from?
(OK, sorry, back to real answers.)
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### Author:  [@digs](https://boards.straightdope.com/u/digs)
#### Post date: [September 19, 2010, 4:35am UTC](https://boards.straightdope.com/t/do-photons-exist/554215/5 "2010-09-19T04:35:08Z")
> [@](#):
>
> Do photons exist?
Yep.
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### Author:  [@digs](https://boards.straightdope.com/u/digs)
#### Post date: [September 19, 2010, 4:38am UTC](https://boards.straightdope.com/t/do-photons-exist/554215/6 "2010-09-19T04:38:04Z")
I’ve always wondered if posters that ask a YES or NO question get amused by the fact that everyone here gives additional information, but without literally just answering the OP.
… hence the Yep.
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### Author:  [@johnpost](https://boards.straightdope.com/u/johnpost)
#### Post date: [September 19, 2010, 5:04am UTC](https://boards.straightdope.com/t/do-photons-exist/554215/7 "2010-09-19T05:04:32Z")
i don’t think so. i’ve never seen any.
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### Author:  [@digs](https://boards.straightdope.com/u/digs)
#### Post date: [September 19, 2010, 5:09am UTC](https://boards.straightdope.com/t/do-photons-exist/554215/8 "2010-09-19T05:09:35Z")
I’ve never seen anything but.
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### Author:  [@johnpost](https://boards.straightdope.com/u/johnpost)
#### Post date: [September 19, 2010, 5:45am UTC](https://boards.straightdope.com/t/do-photons-exist/554215/9 "2010-09-19T05:45:18Z")
> [@johnpost](#):
>
> i don’t think so. i’ve never seen any.
i changed my mind. i just saw one out of the corner of my eye. those guys are fast.
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### Author:  [@digs](https://boards.straightdope.com/u/digs)
#### Post date: [September 19, 2010, 6:10am UTC](https://boards.straightdope.com/t/do-photons-exist/554215/10 "2010-09-19T06:10:11Z")
If you get one in the corner of your eye, you need to wash it out. Right away. Those suckers are pointy.
-
If Dawn doesn’t work, try some Quantum Foam.\*
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### Author:  [@iamnotbatman](https://boards.straightdope.com/u/iamnotbatman)
#### Post date: [September 19, 2010, 7:21am UTC](https://boards.straightdope.com/t/do-photons-exist/554215/11 "2010-09-19T07:21:22Z")
> [@The\_Hamster\_King](#):
>
> From the reference frame of the photon, its trip from A to B takes zero time and covers zero distance. So wouldn’t it make more sense to think of emission/transmission/absorption as a single instantaneous event between two particles that are adjacent to each other? And to think of the apparent passage of a photon between them as merely a useful fiction for describing that event in other reference frames?
First of all, while it is true that in the photon’s reference frame its trip from A to B takes zero time, it is not at all true that in the photon’s reference frame it covers zero distance. I don’t know where you got that from. So the premise of your question is all wrong.
Second of all, it’s true that we don’t “see” a photon unless we interact with it in some way. Therefore one can always argue philosophically that the photon doesn’t exist unless we check. This is sort of like the old question of whether the moon exists when you aren’t looking at it. The answer to both assertions is “sure, but they really _behave_ like they exist, so it’s simplest to just assume they exist.”
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### Author:  [@naita](https://boards.straightdope.com/u/naita)
#### Post date: [September 19, 2010, 10:17am UTC](https://boards.straightdope.com/t/do-photons-exist/554215/12 "2010-09-19T10:17:06Z")
> [@iamnotbatman](#):
>
> > [@The\_Hamster\_King](#):
> >
> > From the reference frame of the photon, its trip from A to B takes zero time and covers zero distance. So wouldn’t it make more sense to think of emission/transmission/absorption as a single instantaneous event between two particles that are adjacent to each other? And to think of the apparent passage of a photon between them as merely a useful fiction for describing that event in other reference frames?
>
> First of all, while it is true that in the photon’s reference frame its trip from A to B takes zero time, it is not at all true that in the photon’s reference frame it covers zero distance. I don’t know where you got that from. So the premise of your question is all wrong.
Actually the premise is completely right. Length contraction means that “to a photon” the universe has zero length in its direction of travel.
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### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [September 19, 2010, 3:01pm UTC](https://boards.straightdope.com/t/do-photons-exist/554215/13 "2010-09-19T15:01:22Z")
> [@](#):
>
> First of all, while it is true that in the photon’s reference frame its trip from A to B takes zero time, it is not at all true that in the photon’s reference frame it covers zero distance. I don’t know where you got that from. So the premise of your question is all wrong.
First of all, it is not at all true that in the photon’s reference frame. A photon does not have a reference frame.
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### Author:  [@iamnotbatman](https://boards.straightdope.com/u/iamnotbatman)
#### Post date: [September 19, 2010, 3:26pm UTC](https://boards.straightdope.com/t/do-photons-exist/554215/14 "2010-09-19T15:26:30Z")
> [@naita](#):
>
> > [@iamnotbatman](#):
> >
> > First of all, while it is true that in the photon’s reference frame its trip from A to B takes zero time, it is not at all true that in the photon’s reference frame it covers zero distance. I don’t know where you got that from. So the premise of your question is all wrong.
>
> Actually the premise is completely right. Length contraction means that “to a photon” the universe has zero length in its direction of travel.
Before considering the photon frame of reference, it might be helpful for you to consider something moving ‘near’ the speed of light. As a particle nears the speed of light, in its reference frame it appears as though he universe is compressed into a short distance. This doesn’t mean that it travels _less_ distance in a given time – it means it travels _more_ distance. In the photon’s reference frame, it takes zero time to traverse the entire universe. It is wrong to say that in the photon’s reference frame it covers zero distance. It covers infinite distance per unit time. Considering the photon’s frame of reference takes some care, since it is a special case (no particle can go faster than light) where the equations begin to yield infinities, and where a knowledge of limits/calculus is going to be helpful. As a particle nears the speed of light, it takes less and less time (in its reference frame) for it to traverse very large distances.
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### Author:  [@iamnotbatman](https://boards.straightdope.com/u/iamnotbatman)
#### Post date: [September 19, 2010, 3:30pm UTC](https://boards.straightdope.com/t/do-photons-exist/554215/15 "2010-09-19T15:30:04Z")
> [@Chronos](#):
>
> > [@](#):
> >
> > First of all, while it is true that in the photon’s reference frame its trip from A to B takes zero time, it is not at all true that in the photon’s reference frame it covers zero distance. I don’t know where you got that from. So the premise of your question is all wrong.
>
> First of all, it is not at all true that in the photon’s reference frame. A photon does not have a reference frame.
Sad photon. It doth exist and yet you allow it no frame of reference?
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### Author:  [@Pasta](https://boards.straightdope.com/u/Pasta)
#### Post date: [September 19, 2010, 4:48pm UTC](https://boards.straightdope.com/t/do-photons-exist/554215/16 "2010-09-19T16:48:16Z")
> [@iamnotbatman](#):
>
> As a particle nears the speed of light, it takes less and less time (in its reference frame) for it to traverse very large distances.
But the asymptotic value of its speed is still _c_, about 300,000 km/s. The just-under-light-speed object doesn’t see itself covering an arbitrarily large distance in an arbitrarily small time. Rather, it sees itself covering just under 300,000 km in every second.
In the limit that the object moves at _c_, it sees itself covering zero distance and taking zero time to do it. You mustn’t mix the distance _we_ see the photon travel with the time _it_ sees the trip taking. If you take both the trip distance and the trip duration from a single reference frame, you’ll get _c_ (although in the photon’s frame, one must step lightly, as things can only be computed as limits.)
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### Author:  [@Lumpy](https://boards.straightdope.com/u/Lumpy)
#### Post date: [September 19, 2010, 7:11pm UTC](https://boards.straightdope.com/t/do-photons-exist/554215/17 "2010-09-19T19:11:40Z")
Perhaps a less controversial way of phrasing the question of the OP might be “between their emission and their absorption, do photons interact with the rest of the universe in any way?” Can one in any meaningful sense say “a photon just passed by”?
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### Author:  [@naita](https://boards.straightdope.com/u/naita)
#### Post date: [September 19, 2010, 8:31pm UTC](https://boards.straightdope.com/t/do-photons-exist/554215/18 "2010-09-19T20:31:09Z")
> [@Lumpy](#):
>
> Perhaps a less controversial way of phrasing the question of the OP might be “between their emission and their absorption, do photons interact with the rest of the universe in any way?” Can one in any meaningful sense say “a photon just passed by”?
When light is bent by a massive object, the momentum of the photon changes, so the massive object needs a change in momentum too. “Ooh, I just felt a photon passing by.”
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### Author:  [@Chimera](https://boards.straightdope.com/u/Chimera)
#### Post date: [September 19, 2010, 9:43pm UTC](https://boards.straightdope.com/t/do-photons-exist/554215/19 "2010-09-19T21:43:44Z")
We can detect Photons, ergo they exist.
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### Author:  [@iamnotbatman](https://boards.straightdope.com/u/iamnotbatman)
#### Post date: [September 20, 2010, 5:29am UTC](https://boards.straightdope.com/t/do-photons-exist/554215/20 "2010-09-20T05:29:31Z")
> [@Pasta](#):
>
> > [@iamnotbatman](#):
> >
> > As a particle nears the speed of light, it takes less and less time (in its reference frame) for it to traverse very large distances.
>
> But the asymptotic value of its speed is still _c_, about 300,000 km/s. The just-under-light-speed object doesn’t see itself covering an arbitrarily large distance in an arbitrarily small time. Rather, it sees itself covering just under 300,000 km in every second.
>
> In the limit that the object moves at _c_, it sees itself covering zero distance and taking zero time to do it. You mustn’t mix the distance _we_ see the photon travel with the time _it_ sees the trip taking. If you take both the trip distance and the trip duration from a single reference frame, you’ll get _c_ (although in the photon’s frame, one must step lightly, as things can only be computed as limits.)
As a factual matter you are simply wrong (btw IAAP). I’m not sure where you are getting mixed up; special relativity can be a tricky subject. From the ‘lab frame’ the photon is seen to travel at speed c. In the photon’s frame it sees a different situation due to the effects of time dilation and length contraction. According to a clock on a photon (if such a thing were possible) it would take zero time for the photon to traverse the entire universe (assuming the photon doesn’t get caught by a black hole and the universe exists long enough, etc).
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