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This a soft question and I can try the chat rooms with it, if that's the consensus for the best place to discuss it. Comments from previous questions I have asked could also sort it out for me.

If I post an answer to an OP saying "your problem is currently impossible to answer because we have not yet been able to directly test our theory", is that in purely formal terms a more correct answer than "YES/NO" based on pure theory. If you look at the fairly straightforward Object Falling At Infinite Speed, you might see what I am getting at.

I hope you understand my motivation here, I really do accept that GPS use, Hulse Taylor, Gravity Probe B etc.. all support G.R.) I also accept that the other answer in the link given above is 99.99999.....% probably correct. But we still have not done a direct test to confirm or refute the particular question.

I completely self study and I don't have any formal background so I don't know much about how the formal science systems works. My motivation for this question is purely to learn more in order to better phrase future questions and answers

thanks

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    $\begingroup$ We don't formally assess the factual correctness of answers here. Useful/correct answers should be upvoted, useless/incorrect answers should be downvoted, and that's it. $\endgroup$ – ACuriousMind Mar 15 '15 at 17:25
  • $\begingroup$ i think giving a practical and theoretical view in a single answer helps . $\endgroup$ – Gowtham Mar 15 '15 at 17:26
  • $\begingroup$ @acuriousmind thanks for that so the most effective way is to present the theory and brief outline of the experimental evidence supporting it if appropriate (and if its that type of question, rather than nuts and bolts definite physical problem). Actually, thinking about it, the key concept is "useful answer" more than anything else, i'm bit slow on the uptake there but that settles it for me question answered as far as i'm concerned $\endgroup$ – user74893 Mar 15 '15 at 17:45
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    $\begingroup$ I really don't understand what is being asked here. $\endgroup$ – David Z Mar 16 '15 at 2:14
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    $\begingroup$ Irish, in contrast to ACuriousMind's comment, I upvote answers that are helpful to me; I don't upvote answers based on some vague idea of what 'ought' to be helpful to others. If I learn something from the answer I upvote it otherwise I don't - even if I think it is an otherwise great answer. On the other hand, I don't downvote answers I find to be unhelpful; I downvote only when the answer is, on my view, blatantly wrong. All of this is to point out that upvotes and downvotes are not the ideal measure of great questions and answers. This has already been discussed here. $\endgroup$ – Alfred Centauri Mar 16 '15 at 2:46
  • $\begingroup$ @davidz I'm a newbie on SE and all I wanted to know was what should I tell the op when he asked "is the speed inside a black hole infinite"? Although we have a theory , g.r, that has been confirmed in countless ways, i was confused that, because it has not been tested for his particular question, (see above), as to whether I should tell him , that as yet it is impossible to answer his question. I was ,correctly in my view, told that the aim of the site was to provide useful answers rather than get caught up in formally factual ones. I simply want to learn how to answer questions correctly $\endgroup$ – user74893 Mar 16 '15 at 2:47
  • $\begingroup$ "I simply want to learn how to answer questions correctly" - Sigh... your aim is off. $\endgroup$ – Alfred Centauri Mar 16 '15 at 2:50
  • $\begingroup$ So far , my answers have been extremely useful to me and I guess from their responses, useful to about half the o'ps. I'm happy with that and the concept of usefulness, to whoever it benefits,being used as basis of correct answers. In other words, I know what to do now,give the most useful answer I can....and that's it...just a newbie looking for advice on how to answer questions properly from people with more experience than me. $\endgroup$ – user74893 Mar 16 '15 at 2:58
  • $\begingroup$ It's my question and I answered myself a good few hours ago , so I think it's my privilege to formally close the proceedings and say goodnight (2 am) here. Seriously ,thanks to all , let's leave at that and get back to real physics $\endgroup$ – user74893 Mar 16 '15 at 3:12
  • $\begingroup$ @irishphysics (4 comments up) OK, well that wasn't clear to me from the question. $\endgroup$ – David Z Mar 16 '15 at 4:06
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The key point about an answer is that it should be useful and informative, not only for the person asking the question but for anyone else interested enough to read it.

Let's take the question you link as an example. The tone of the question suggests the OP has learned some facts about black holes (I would from popular science books/TV programmes) but doesn't have any real knowledge of general relativity. My aim when answering was to answer the question, but also try and explain why we get that answer and explain some of the background. The idea is that anyone reading my answer will leave feeling wiser. Actually I'm not sure I've really achieved this since I did kind of just trot out some formulae and graph them - I really must go back to the answer and add more detail.

But to just say:

Nobody, not the best people we have, nobody, knows what goes on inside a black hole.

is massively unhelpful. It's true that we don't have a nearby black hole to do experiments on, so all our theories are just theories. However there are lots of tests of GR and it's well enough establshed that we ca feel confident about using it to make predictions (like the graphs I drew). It's also true that the region of spacetime inside the event horizon is causally disconnected from the region outside, so we'll never have experimental tests of what happens inside it. But we have coordinate systems that cross the event horizon smoothly so (apart from the wilder excesses of string theorists) there is no reason to suppose that general relativity stops working at the event horizon.

If your answer had said we don't know, but then gone on to make the points I've raised above then it would be a reasonable answer but still less informative than it could be. As it is, your answer is true but leaves the reader no better off for having read it.

There is a satisfaction in having learned and/or understood something that was new and opaque. Everyone feels this, not just us nerds, which is how the Discovery Channel makes its money. A good answer on this site should fulfill this need - hopefully more rigorously than the Discovery Channel does. Admittedly, many readers will simply take away a new "gee whizz it's like magic" fact to impress their friends with, and I have no problem with that. But maybe a few readers will have a genuine interest sparked, and even one day become physicists.

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  • $\begingroup$ thanks john my reply is below. $\endgroup$ – user74893 Mar 16 '15 at 11:08
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the most effective way is to present the theory and brief outline of the experimental evidence supporting it if appropriate (and if its that type of question, rather than nuts and bolts definite physical problem). Actually, thinking about it, the key concept is "useful answer" more than anything else, i'm bit slow on the uptake there but that settles it for me question answered

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