# Viewer of past events? **URL:** \ **Category:** Cafe Society\ **Created:** [December 2, 2012, 10:47pm UTC](https://boards.straightdope.com/t/viewer-of-past-events/642794 "2012-12-02T22:47:48Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![JohnClay](https://avatars.discourse-cdn.com/v4/letter/j/c37758/32.png) [@JohnClay](https://boards.straightdope.com/u/JohnClay)\ **Post date:** [December 2, 2012, 10:47pm UTC](https://boards.straightdope.com/t/viewer-of-past-events/642794/1 "2012-12-02T22:47:48Z")
In the “Masters of the Universe” movie there was a machine that let Evil Lyn(?) view what happened in the past to areas she was pointing the device at. It doesn’t seem to be mentioned here though: > **[Masters Of The Universe](https://tvtropes.org/pmwiki/pmwiki.php/Film/MastersOfTheUniverse)** > > A 1987 film directed by Gary Goddard for The Cannon Group, a Live Action Adaptation of the toy/animation franchise of the same name. The movie features Skeletor acquiring the Cosmic Key, a teleportation device from Gwildor, an eccentric inventor … I think that such a device that could tune into different times and even different locations in the past wouldn’t cause any time travel problems. If the machine was sensitive enough it would even be about to detect what sounds are happening in the past. It would cause some problems though - e.g. you could find out people’s passwords by slowly replaying video from the past. It would be good for court cases though. I was wondering has that machine appeared in other movies or been mentioned by futurists or something? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [December 2, 2012, 11:25pm UTC](https://boards.straightdope.com/t/viewer-of-past-events/642794/2 "2012-12-02T23:25:13Z")
It crops up a fair bit in SF stories - sometimes the physical range is limited (i.e. you can only track events that happened within a radius of where the device is situated), sometimes the temporal range is limited (you can watch what Shakespeare was up to, but not what someone did yesterday), sometimes, each event can only be viewed once. It was a major plot device in the movie _Deja Vu_ ---
**Author:** ![samclem](https://avatars.discourse-cdn.com/v4/letter/s/a9a28c/32.png) [@samclem](https://boards.straightdope.com/u/samclem)\ **Post date:** [December 2, 2012, 11:30pm UTC](https://boards.straightdope.com/t/viewer-of-past-events/642794/3 "2012-12-02T23:30:56Z")
Better suited to Cafe Society. Moved from General Questions. **samclem** , moderator ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [December 2, 2012, 11:38pm UTC](https://boards.straightdope.com/t/viewer-of-past-events/642794/4 "2012-12-02T23:38:45Z")
The [time viewer](http://en.wikipedia.org/wiki/Time_viewer#Stories_featuring_time_viewers) is a standard device in science fiction. That page only takes it back to the 1940s but it’s definitely older than that. There are obvious privacy issues that such a device raises, and that’s the plot of Asimov’s “The Dead Past.” Which laws of physics it violates probably depends on the exact details of its construction. I’m sure it violates some and therefore can’t really exist. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [December 3, 2012, 12:20am UTC](https://boards.straightdope.com/t/viewer-of-past-events/642794/5 "2012-12-03T00:20:17Z")
There are no fundamental physical laws broken by a time viewer. It’s fundamentally no different than what an archaeologist or paleontologist does: Studying something in the present to gain information about the past. It may not be practical to get information anywhere near as detailed as is described in science fiction, but that’s another matter. ---
**Author:** ![Tangent](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tangent/32/3098_2.png) [@Tangent](https://boards.straightdope.com/u/Tangent)\ **Post date:** [December 3, 2012, 12:46am UTC](https://boards.straightdope.com/t/viewer-of-past-events/642794/6 "2012-12-03T00:46:19Z")
In Arthur C. Clarke’s _Childhood’s End_, the Overlords give humans the technology to look into the past, and it brings an end to religion. ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [December 3, 2012, 12:53am UTC](https://boards.straightdope.com/t/viewer-of-past-events/642794/7 "2012-12-03T00:53:52Z")
Heck, a “voice machine” that could pull long-faded sounds out of the air (a demonstration picked up the Gettysburg Address) was the focus of several episodes of the 1940s Superman radio show. The plot segues when the characters point it at the city and happen across a conversation about a murder. ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [December 3, 2012, 2:05am UTC](https://boards.straightdope.com/t/viewer-of-past-events/642794/8 "2012-12-03T02:05:48Z")
Here’s a kicker: suppose there isn’t really one fixed past? We don’t really know anything about the past; we know about the present, including our memories and what we observe, and deduce the past. If different possible pasts could converge on identical presents then maybe all of them are equally valid, and a time viewer would show different views weighted by probability until the past vanished into a fog. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [December 3, 2012, 3:29am UTC](https://boards.straightdope.com/t/viewer-of-past-events/642794/9 "2012-12-03T03:29:47Z")
> [@Chronos](#): > > There are no fundamental physical laws broken by a time viewer. It’s fundamentally no different than what an archaeologist or paleontologist does: Studying something in the present to gain information about the past. It may not be practical to get information anywhere near as detailed as is described in science fiction, but that’s another matter. Studying something means interacting with it. You have to detect/observe/record the photons involved. You’re either sending a probe into the past or picking up the photons instantaneously at a distance of x lightyears where x is the number of years they’ve existed or some variation. I can’t see any way that doesn’t violate causality. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [December 3, 2012, 3:38am UTC](https://boards.straightdope.com/t/viewer-of-past-events/642794/10 "2012-12-03T03:38:40Z")
That’s _if_ you’re using photons. An object interacts with many other particles, many of them slower-than-light or stationary (in some reasonable choice of reference frame), and you could in principle get information from any of them. ---
**Author:** ![JohnClay](https://avatars.discourse-cdn.com/v4/letter/j/c37758/32.png) [@JohnClay](https://boards.straightdope.com/u/JohnClay)\ **Post date:** [December 3, 2012, 6:57am UTC](https://boards.straightdope.com/t/viewer-of-past-events/642794/11 "2012-12-03T06:57:03Z")
> [@Exapno\_Mapcase](#): > > Studying something means interacting with it. You have to detect/observe/record the photons involved. You’re either sending a probe into the past or picking up the photons instantaneously at a distance of x lightyears where x is the number of years they’ve existed or some variation. I can’t see any way that doesn’t violate causality. Perhaps it isn’t possible to study past events to a very high level of precision an unlimited number of times… like how archaeology involves making some changes… or maybe there is a thing like X-rays that could involve things being analysed without really affecting the original… ---
**Author:** ![JohnClay](https://avatars.discourse-cdn.com/v4/letter/j/c37758/32.png) [@JohnClay](https://boards.straightdope.com/u/JohnClay)\ **Post date:** [December 3, 2012, 7:01am UTC](https://boards.straightdope.com/t/viewer-of-past-events/642794/12 "2012-12-03T07:01:22Z")
> [@Lumpy](#): > > Here’s a kicker: suppose there isn’t really one fixed past? We don’t really know anything about the past; we know about the present, including our memories and what we observe, and deduce the past. If different possible pasts could converge on identical presents then maybe all of them are equally valid, and a time viewer would show different views weighted by probability until the past vanished into a fog. Maybe this is true - after all apparently Stephen Hawking was promoting that kind of idea… > **[Exploring Stephen Hawking's Flexiverse](https://www.newscientist.com/article/mg19025481-300-exploring-stephen-hawkings-flexiverse/)** > > HERE'S how to build a universe. Step one: start at the beginning of time. Step two: apply the laws of physics. Step three: sit back and watch the universe evolve. Step four: cross your fingers and hope that it comes out looking something like the one... ---
**Author:** ![Little\_Nemo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/little_nemo/32/3120_2.png) [@Little\_Nemo](https://boards.straightdope.com/u/Little_Nemo)\ **Post date:** [December 3, 2012, 7:23am UTC](https://boards.straightdope.com/t/viewer-of-past-events/642794/13 "2012-12-03T07:23:10Z")
“E for Effort” by T.L. Sherred is another classic science fiction story based on this idea. ---
**Author:** ![grude](https://avatars.discourse-cdn.com/v4/letter/g/e47774/32.png) [@grude](https://boards.straightdope.com/u/grude)\ **Post date:** [December 3, 2012, 7:49am UTC](https://boards.straightdope.com/t/viewer-of-past-events/642794/14 "2012-12-03T07:49:04Z")
The movie Final Edit is kinda based on this idea, but it is a special chip people are implanted with that records their entire life and is viewable on death. ---
**Author:** ![Tangent](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tangent/32/3098_2.png) [@Tangent](https://boards.straightdope.com/u/Tangent)\ **Post date:** [December 3, 2012, 9:16am UTC](https://boards.straightdope.com/t/viewer-of-past-events/642794/15 "2012-12-03T09:16:24Z")
^That was [The Final Cut](http://www.imdb.com/title/tt0364343/). ---
**Author:** ![grude](https://avatars.discourse-cdn.com/v4/letter/g/e47774/32.png) [@grude](https://boards.straightdope.com/u/grude)\ **Post date:** [December 3, 2012, 11:23am UTC](https://boards.straightdope.com/t/viewer-of-past-events/642794/16 "2012-12-03T11:23:37Z")
> [@Tangent](#): > > ^That was [The Final Cut](http://www.imdb.com/title/tt0364343/). Doh! ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [December 3, 2012, 5:29pm UTC](https://boards.straightdope.com/t/viewer-of-past-events/642794/17 "2012-12-03T17:29:53Z")
> [@Chronos](#): > > That’s _if_ you’re using photons. An object interacts with many other particles, many of them slower-than-light or stationary (in some reasonable choice of reference frame), and you could in principle get information from any of them. Could you give some examples of how such a time viewer would work? > [@JohnClay](#): > > Perhaps it isn’t possible to study past events to a very high level of precision an unlimited number of times… like how archaeology involves making some changes… or maybe there is a thing like X-rays that could involve things being analysed without really affecting the original… X-rays obviously interact with something or else you wouldn’t see any picture at all. ---
**Author:** ![KneadToKnow](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kneadtoknow/32/3999_2.png) [@KneadToKnow](https://boards.straightdope.com/u/KneadToKnow)\ **Post date:** [December 3, 2012, 8:48pm UTC](https://boards.straightdope.com/t/viewer-of-past-events/642794/18 "2012-12-03T20:48:26Z")
> [@Tangent](#): > > In Arthur C. Clarke’s _Childhood’s End_, the Overlords give humans the technology to look into the past, and it brings an end to religion. Stephen Baxter visited the idea again in _The Light of Other Days_, which Clarke wrote the synopsis for. Clarke’s afterword discusses the use of such devices in SF. ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [December 3, 2012, 9:23pm UTC](https://boards.straightdope.com/t/viewer-of-past-events/642794/19 "2012-12-03T21:23:08Z")
> [@Lumpy](#): > > Here’s a kicker: suppose there isn’t really one fixed past? We don’t really know anything about the past; we know about the present, including our memories and what we observe, and deduce the past. If different possible pasts could converge on identical presents then maybe all of them are equally valid, and a time viewer would show different views weighted by probability until the past vanished into a fog. I’ve seen stories with that theme as well. In one, the protagonist saw a different past, equally consistent with the present, each time he used the devide to see a particular past event. This was very disturbing for him when he watch the Resurrection and got multiple results. ---
**Author:** ![JohnClay](https://avatars.discourse-cdn.com/v4/letter/j/c37758/32.png) [@JohnClay](https://boards.straightdope.com/u/JohnClay)\ **Post date:** [December 3, 2012, 10:48pm UTC](https://boards.straightdope.com/t/viewer-of-past-events/642794/20 "2012-12-03T22:48:02Z")
> [@Exapno\_Mapcase](#): > > …X-rays obviously interact with something or else you wouldn’t see any picture at all. My point is that a large number of X-rays can probably be taken of something before the object analysis starts to have less precision. [Next page](https://boards.straightdope.com/t/viewer-of-past-events/642794.md?page=2)