Plot Details/Summary

The premise of this tale is that a scientist, or small group of scientists, have created a device that will allow them to open a viewing portal to the past. With it, the operator can watch events unfold from a given time/place through the created portal. The portal is one way, so the observed cannot see the observers. The one quirk in the design is that when it is activated, it creates a glowing outline of the where the portal has manifested in the past. Both as it forms, and for a time afterwards, IIRC.

The bulk of the story details with the scientists (possibly also historians of a sort?) observing the construction of Stonehenge. There are passages about the stone being hauled up, etc. I don't recall if the viewing was time-lapse or real time. As the viewing ends, the scientists in the present consider the entire experiment to be a resounding success and an historical breakthrough.

It is then we get the story's twist. One of the other scientists suddenly raises a concern with the lead scientists. Since the glowing effect of the portal would have been visible well-before they began viewing the construction of Stonehenge, and probably would have been seen as magical or unearthly, what if their own experiment was the inspiration for Stonehenge? (There is a term for this sort of effect, I believe, but I cannot recall what it is).

Publication Details

I read this one in the 1980s, as usual. I'm almost positive that it was part of an anthology in my dad's collection. I'd guess 1970's or earlier for the story's publication date.

  • 15
    "There is a term for this sort of effect, I believe, but I cannot recall what it is" Closed time loop, stable time loop, causal loop, predestination paradox. May 15, 2018 at 15:20
  • 1
    Time Parodox. As the reason for the trip back was because they made a trip back already which caused the Henge to be built. May 15, 2018 at 15:38
  • 11
    That's not really a time paradox, just reverse causality. Now, if their observations had caused stonehenge to not be built, that would be a time paradox. May 15, 2018 at 16:14
  • 3
    This literally sounds like something Futurama's Professor Farnsworth would do. May 15, 2018 at 16:17
  • 1
    @PeteBecker Yes. I am not sure what a specified-end thing like what Ochuko Sagua is called, but a paradox is something that results in something else that resulted in the first result not happening, therefore causing the second result to not happen, causing the first result and then the second result to happen, and etc. May 15, 2018 at 16:41

1 Answer 1


This is "The Secret of Stonehenge" by Harry Harrison as per this Goodreads discussion, and is available at the Internet Archive as user14111 pointed out.

Unfortunately, I've yet to find a description to quote, but it's just as you recall, that the afterimage of the time machine was why they built Stonehenge. The closest I've found is the summary here:

In "The Secret of Stonehenge," a chronostasis temporal-recorder allows two men to take pictures of events in the past-as far back as 10,000 B.C

Here's the ending of the story:

"Correct. The golden glow of the machine caused by all those stops must have been visible on and off for years. It gave me a jolt when I first saw it, and it must have been much more impressive to the people then."

"It fits," Lanning said, smiling happily and beginning to repack the machine. "They built Stonehenge around the image of the device sent back to see why they built Stonehenge. So that's solved."

"Solved! The problem has just begun. It's a paradox. Which of them, the machine or the monument, came first?"

Slowly, the smile faded from Dr. Lanning's face.

  • 1
    Wow, that was quick! Definitely the story I am looking for here. Will accept answer as soon as site lets me.
    – Helbent IV
    May 15, 2018 at 14:35
  • 3
    @HelbentIV: I was recently rereading Stainless Steel Visions, which has this and a story I recently got the answer to (as well as another from a few years back that I asked).
    – FuzzyBoots
    May 15, 2018 at 14:36
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    As I remember, they send the machine to the center of Stonehenge. But however they turn it, the people always seem to be looking straight at it. Also, the machine leaves an afterglow in the present. The scientists realise that it must leave an afterglow in the past too, which is what the people were worshipping.
    – SQB
    May 15, 2018 at 17:38
  • 7
    Of course the story is available at the Internet Archive.
    – user14111
    May 15, 2018 at 18:55
  • 3
    As I recall they send a camera on a tripod back to stone henge and the image shows a worshipping crowd bowing towards the camera, they decide that the object of worship is behind the camera, so they turn the camera around and send it back, the new image also shows a worshipping crowd and they realise they are worshipping the camera
    – Bob
    May 20, 2018 at 19:49

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