1. Standard memberDeepThought
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    12 Jul '16 13:28
    Originally posted by sonhouse
    In science i don't think you can use fact, as in 'it is a fact there will never be teleportation like star trek' since we cannot know the future of science. We can say 'it is highly unlikely for there ever to be teleportation like star trek' or something like that but you can't just say something is a fact about future tech.

    You can say I suppose, 'its a ...[text shortened]... fact if you are at ground zero of a 1000 ton meteorite you will die when it lands on your head'.
    I don't think new information represents the problem. That caveat would just be built into any scientific usage of the word fact. The problem is equivocation, it's never quite clear whether a fact is a theory or a thing. This distinction is important in science. I think the sense of "fact" the Oxford dictionary gives as chiefly law which is essentially brute fact would be the sense it would be used in in Science, if at all, with the additional scientific truth test requirement that I mentioned above. That it is used in this way would tend to "future proof" it as what counts as facts then are specific experimental results, rather than the interpretation of the results, additional information changing a theory about the data wouldn't affect the (brute) facts, but the theory. So, in the sense I'm advocating your example sentence "It is a fact [that] there will never be teleportation like [in] Star Trek." is not a scientific fact because it refers to a theory (interpretation) rather than any particular experimental results (the facts) collected. It is a scientific fact that Sirius has an apparent parallax of 379 milliarcseconds because it is a straightforward, if tricky, measurement of its movement relative to more distant stars. The distance calculation depends on the interpretation that what appears to be parallax is in fact the effect of parallax.
  2. Subscribersonhouse
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    12 Jul '16 15:28
    Originally posted by DeepThought
    I don't think new information represents the problem. That caveat would just be built into any scientific usage of the word fact. The problem is equivocation, it's never quite clear whether a fact is a theory or a thing. This distinction is important in science. I think the sense of "fact" the Oxford dictionary gives as chiefly law which is es ...[text shortened]... epends on the interpretation that what appears to be parallax is in fact the effect of parallax.
    What is the difference between 'what appears to be parallax V the effect of parallax'?

    You see the star in December and read such and such an angle and then again in July and you see such and such angle and get the apparent shift, so why isn't that just the parallax, not the effect of parallax? We know the STAR didn't move much so what else are we to derive from such measurements?
  3. Cape Town
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    12 Jul '16 16:12
    Originally posted by DeepThought
    No, I don't think I was at all ambiguous, .
    Yes, you are correct. I must have got confused reading various posts in this thread and the one in spirituality.
  4. Cape Town
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    12 Jul '16 16:17
    Originally posted by sonhouse
    What is the difference between 'what appears to be parallax V the effect of parallax'?

    You see the star in December and read such and such an angle and then again in July and you see such and such angle and get the apparent shift, so why isn't that just the parallax, not the effect of parallax? We know the STAR didn't move much so what else are we to derive from such measurements?
    Do you know the star didn't move? Do you know the true structure of space between us and the star? You may be very confident, but there is significant interpretation going on whereas the observation itself is on more solid ground. Certainly it is entirely within the realm of possibility that parallax is not the only effect involved. It is also possible the measurements are wrong, but once several independent people have measured it we more or less take it that we could not possibly be wrong on that score.
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    12 Jul '16 17:423 edits
    Originally posted by twhitehead
    Do you know the star didn't move?
    He said not that it doesn't move but it doesn't move much implying that that movement is negligible for this context.
  6. Cape Town
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    12 Jul '16 18:06
    Originally posted by humy
    He said not that it doesn't move but it doesn't move much implying that that movement is negligible for this context.
    I realise that. My question is how sure he is that its movement was negligible. Is it certain enough to be called a fact?
  7. Standard memberDeepThought
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    12 Jul '16 21:241 edit
    Originally posted by sonhouse
    What is the difference between 'what appears to be parallax V the effect of parallax'?

    You see the star in December and read such and such an angle and then again in July and you see such and such angle and get the apparent shift, so why isn't that just the parallax, not the effect of parallax? We know the STAR didn't move much so what else are we to derive from such measurements?
    Parallax is the name of the effect of apparent movement of a closer object relative to a more distant one due, in fact, to the perspective of the observer changing due to his or her movement. What was measured was this apparent movement relative to the more distant background. It is interpreted as parallax, but for this discussion we need the adjective "apparent", because it is a theory that such movement is caused by parallax and not some other effect we do not know about.

    Originally, I was going to compare distances measured in parsecs (reciprocal of apparent parallax) and light-years (a unit of distance), but then realized that actually I had to assume things about geometry, that our theories of space-time make taking that reciprocal the right thing to do. So I went parallax instead, and to be certain added the adjective apparent, as that the motion is cause by parallax is a theory.
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