[High Praise! to Saturday Morning Breakfast Cereal]
Faster Than the Speed of Light
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I didn’t care for the line:”That’s the difference between Real and Unreal.” A better wording would be : “That’s the difference between Appearance and Reality.”
The shadow is not a single event: it is the result of uncountable photons all acting individually according to the laws of physics and hitting the screen individually.
The shadow isn’t moving, the photons are all hitting the screen at slightly different times across a trillion miles.
A confluence of events is not a single event, nor is it “unreal,” per se, it is merely a deceptive appearance.
For example: The confluence of an African-American man being articulate and bright and clean, light-skinned and speaking with no negro dialect, unless he wants to have one might give the appearance of someone who might might a good President, especially if his trousers had a sharp crease.
Again, not unreal, just deceptive in appearance.
Right word, lightning, lightning bug and all that.
Well, as long as hari’s going to be all logical and all . . .
Einstein would say that the proposed shadow of your hand would propagate across space (at most) at the speed of light, so the shadow would not cross the far-away screen at greater than the speed of light.
Each section of that giant screen would get its shadow in its appropriate time, at the speed of light.
Consider, by analogy, how the instantaneous explosion of the Sun would not affect the Earth for several minutes afterwards.
Or how the death of star far away is not visible to us right now.
Why would the extinguishing of the projector’s light be visible to that star’s Jumbotron screen any faster?
Oppo,
It’s like when someone walks in front of a movie projector: It may only take them a second to cross the light stream, and their shadow will cross the screen in the same amount of time because of the way the light diffuses between the projector and the screen.
How does one actually observe, in total, a screen 1 trillion miles across without the same time lag caused by the speed of light constraint?
The screen is 50 trillion miles away,, which is 8.5 light years away. I assume (perhaps incorrectly) that these distances were chosen to make the screen appear like a movie screen, or a big screen TV, maybe, and that all points of the screen are equidistant from the light source, which would negate the time lag. (It would probably have to be curved to accomplish that.) So it would be like watching a movie. I guess.
But of course, gain, you’d have to wait 17 years to see it from the source, and the Caliphate will probably have killed us all by that point, so the point is kind of moot. Of course, the idea of a trillion mile wide screen renders the argument moot from the start, but we can dream, can’t we?
On the other hand, the closer you are to the screen, the faster the apparent speed the shadow will move across the screen, simply due to the scale of the thing.
Here’s an entirely unrelated question: We know 1). There is a speed of light, at which photons travel, and we know 2). Gravity affects all particles in the Universe and 3). There is a theoretical particle known an the “graviton,” which to gravity what the photon is to light. So: Is there a “Speed of Gravity?” If a unit of mass were to suddenly appear from nowhere (hypothetically), would it affect all other mass in the universe simultaneously, or would there be a wave effect radiating outward from the new mass?
These are the kind of things that keep me awake at night.
In the end it will still be better than anything Hollywood has produced recently.
Come to think of it, I believe I saw that “Shadow Crossing Trillion Mile Screen” is the next film from Was Anderson, which critics will call “powerful” and “amazing” and hilarious” and “the must-see movie of the year,” but which, when you see it, will cause you to think, “What was that even about?” and “That was a comedy?” and “I guess I just don’t get it,” before realizing that the critics don’t get it either, but just pretend they do make all their pronouncements so all their friends will think they’re smart