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A couple of things might help here...So, another way to ask my question is: How far into the 'future' (particularly the future of the Universe), can you look? Can anyone look? Using any kind of instrumentation whatsoever? How far? To put it, the question, right, how far can you see into 'space'?
It's interesting that Roemer discovered in 1676 that those orbital periods for the Moons all were slower when Earth was farther away from Jupiter, and faster when closer. This allowed him to recognize that the speed of light isn't infinite and he was able to somewhat accurately calculate the speed of light.Atlan0101, your post #6 question is interesting. "How far into the 'future' (particularly the future of the Universe), can you look?"
I would start where Galileo did when he looked at Jupiter, observing the Galilean moons moving around Jupiter in a telescope. Galileo documented his observations and today, some 400 years later, I can still see what he did but with better telescopes So when I look at Io moving around Jupiter using my telescope, do I see Io in the future, or the past of Io because of light-time to Earth?
It's impossible to observe anything in the future as, by formal definition, it ain't here yet. If we are observing something it is either something now or something that has come from the past. All light entering the eye took time to reach the eye, hence all light is from the past. If we know the distance, however, then we know the time it took for light to get here.Helio's observation about Roemer and light-time at Jupiter in post #9 is why I ask my question in post #7, "So when I look at Io moving around Jupiter using my telescope, do I see Io in the future, or the past of Io because of light-time to Earth?"
Thanks!Helio's thinking in post #11 is correct because of light-time to Earth. When I view the Galilean moons moving at Jupiter, that is their past I see, those moons have already moved to some other location at Jupiter when I see them in the telescope eyepiece because of light-time. The same is true for my observations of Mars last night using my telescope. The same is true for telescope observations of the bright star Sirius or the bright stars in Orion's belt, now visible in early morning skies. When it comes to tachyons, my telescopes do not see these particles
Helio, very good. You pass my Galileo test
I suspect they, 'tachyons', would have a second name and second dimension of existence. To wit, 'gravitons'.Thanks!
As for tachyons, these are likely not observable in the visible band, even if they exist. [I'm guessing.] It will be a huge discovery if they become a part of mainstream science.