811: Starlight

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Don't worry! From the light's point of view, home and your eye are in the same place, and the journey takes no time at all! Relativity saves the day again.
Title text: Don't worry! From the light's point of view, home and your eye are in the same place, and the journey takes no time at all! Relativity saves the day again.


Megan talks with Beret Guy about the journey of light through the universe from its source to our eyes. In Megan's opinion, it is very sad that this journey is pointless - light's travel ends only with us seeing "pretty dots" - stars in the sky. Beret Guy then tries to return light to its birthplace by using a mirror, which reflects light back to its source.

The title text is a reference to special relativity, which states that from the point of view of a light particle, the distance is zero because it is moving at the speed of light, so it takes no time to go anywhere. Note that the title text says that relativity saves the day again. This could be a reference to a previous comic 660: Sympathy in which a socially inept physicist touches upon using some consequences of special relativity to save a friend's deceased brother.


[The comic consist of six black panels with white drawings. There are stars above the characters in all panels.]
[Megan and Beret Guy stares at a starlit sky. The text is written above the stars and the sentence continues into the next frame. First here it becomes apparent that it is Megan who speaks the entire comment.]
Megan: The starlight falls on our eyes after a journey across trillions of miles-
[Zoom in on Megan and Beret Guy. The continued text is shown to come from Megan via a speech line.]
Megan: dying here at last, so far from home, all so we can see some pretty dots.
[Beret Guy think for a moment]
[Beret Guy runs away]
[Beret Guy comes back with a mirror under his arm, the starry sky can also be seen in the mirror.]
[Beret Guy reached Megan, and holds it up above his head pointing it towards the stars.]

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I thought that was a picture frame, a mirror makes more sense. 08:40, 17 July 2013 (UTC)

From the light's point of view, EVERYTHING is in the same place. The whole universe in one point. {{unsigned ip|}}

Actually, I think that the universe would be a solitary plane. Since light moves only in one straight line. 02:14, 5 March 2015 (UTC)

I still think it's a picture frame. 00:50, 6 August 2014 (UTC)

It's a mirror, you can see the reflection of his arms. 18:35, 27 March 2015 (UTC)

Actually, what you see is a reflection of one arm and of his torso. The other arm is behind the mirror (for that's what it is, though I admit that at first I thought it was a picture frame, also) and is not reflected. Look at the position of the hand of that arm.... well in front of Beret-guy's torso. BTW, it really helps to zoom into this image to understand Randall's attention to detail, yet again. 18:39, 2 July 2017 (UTC)

I am still of the opinion, sort of, that it is a picture frame. It seems like beret guy to make art of things we consider simple, because of the actually extraordinary circumstances that happened to make it so. The Goyim (talk) 23:35, 11 March 2015 (UTC)

It's a mirror. Picture frame makes no sense. It's a mirror. -Pennpenn 06:41, 10 August 2015 (UTC)

This is pushing into areas beyond my expertise, but I question the validity of the assertion that the light particle will experience no time between departing the star and arriving at the planet. From what I understand, One of the pillars of relativity is that from ALL reference frames the speed of light is constant. So when we discuss things "from the point of view of a light particle" most of what we say is basically conjecture. It is impossible to have a valid reference frame moving along with a photon. To say that from the photon's point of view no time passes is to assume a reference point where the speed of light is no longer constant, but instead photons have the ability to be stationary. A stationary photon can never be observed in any valid reference frame. It is fair to say that a particle traveling at a speed infinitesimally less than the speed of light will experience almost no time between locations, but time dilation follows a curve that is only valid for speeds approaching but not including the speed of light.

---I'm not a physicist, but I'm fairly certain you can have a valid light-speed frame of reference. As I recall, that's part of the explanation for how the weak force can distinguish left-handed particles from right-handed ones. This makes no sense at first blush, because whether a particle is spinning left or right depends upon the position of the viewer. You could have one person observe a left handed particle decay while an observer at a different angle observes a right handed particle do nothing. The answer is that if the particle has no intrinsic mass, all observers would agree that it is traveling at the speed of light, and that there is a well-defined left and right (with respect to the direction of the particle's motion). This becomes immensely more complicated because it applies to particles that have no intrinsic mass, but nonetheless obtain effective mass through the Higgs mechanism (for instance, leptons). 18:16, 11 September 2015 (UTC) - NotaphysicistbutIplayoneontheinternet

There is also the obvious futility of the exercise: only a tiny fraction of the photons emanating from a star will reach the mirror and, even if the mirror is held at the perfect orientation, with dispersion (even if the mirror is perfectly smooth, the atmosphere is not) the probability that even one photon will make it back 'home' is effectively nil. Maybe off-topic, but this reminds me of the occasional media circus event when some random marine mammal is beached and then a massive rescue effort is affected to 'save' it). Mountain Hikes (talk) 23:41, 1 January 2016 (UTC)

He should be using a right angle reflector, not a single flat mirror. 01:42, 29 January 2017 (UTC)

I got the impression that Beret Guy wasn't trying to return the light itself back to the stars, but give the stars the same pretty image they get on Earth by "looking" at the mirror. Seems more poetic of him. Could be either or though, I guess. 05:33, 24 October 2016 (UTC)