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Telescope Sees Star Dance Around Supermassive Black Hole, Proves Einstein Right (eso.org)
141 points by lelf on April 17, 2020 | hide | past | favorite | 65 comments



Once again fails to falsify Einstein's prediction This notion that anything is ever fully proven needs to stop being spread around. Maybe pedantic, but the anti-science crowd latches on to things like this - e.g. 'Science is claiming to have all the right answers just as much as religion!' No it doesn't, it has a long, long list of wrong answers, and a short list of answers that haven't yet been proven wrong, which makes up our current best approximation of 'the truth'. Einstein's theory just withstood another attack, so it gets to keep its crown for now.


No, you're mistaken. A _prediction_ was made and matches experiment, therefore the _prediction_ was proven correct.

I believe you're repeating the idea that "_theories_ aren't proven correct, you can only ever fail to falsify them", which is true. But you're applying the idea to predictions, which makes it false because predictions absolutely can be proven correct. In my opinion you come across as confused about these ideas.


You are correct, my comment should have read 'theory' rather than prediction. Alas it is too late for me to edit it, so it will be forever wrong.


Fortunately, HN has a list of your other comments, many of which have yet to be proven wrong.


But does it? This is merely one entry in a long line of evidence consistent with the prediction. Wouldn't it be better to say it did not falsify the prediction?

If this had not been consistent with the prediction, the precession of Mercury still was, so then one needs to sort out what that means. Was one of the experiments flawed? What's the statistical certainty of each, etc.

I don't see how a prediction can be proven true anymore than a theory can.


Isaac Asmiov's The Relativity of Wrong is a wonderful essay on this.

https://chem.tufts.edu/AnswersInScience/RelativityofWrong.ht...


A somewhat superficial acquaintance with the philosophy of science has led some people to think it is more sophisticated - or even more correct - to talk of theories as not having been falsified rather than having evidence in their support.

Having said that, I think the concern here is exaggerated.


Even more sophisticated:

Theories have:

- an expected domain of applicability

and might have:

- applications (either in the sense of experimental physics, or even applications in the sense of theoretical physics)

So a more important question is, do we have evidence against a theory in its domain of applicability in a magnitude that invalidates some use cases?

It's perfectly ok if you find evidence against a theory outside of its domain of applicability (i.e. I don't care if it's wrong in situations I didn't expect it to be right) or if that evidence causes errors so small as to make no difference for my applications.


The point isn't really whether a theory is 'not falsified' or 'has evidence in its support' (they sound roughly equivalent, at least if you formulate it 'has _only_ evidence in its support'), the point is that nothing is ever _proven_, it is only ever not yet disproven. We're collecting an ever larger body of evidence that any theory's predictions need to match in order for the theory to not be proven wrong. Of course the more predictions a theory gets right, the less our need for another theory to make better predictions with instead.


> just withstood another attack

That‘s also a wrong simplification. It wasn’t an attack at all. When science reaches new limits and an old theory is confirmed valid even there, what‘s left is even less possibilities for some new theory to make a different prediction. Any new theory must be compatible with the old one in all these already checked places.


> Any new theory must be compatible with the old one in all these already checked places.

Just like Einstein's theories are compatible with Newton's at much-lower-than-light speeds.


Mercury would like to have a word with you.


In case anyone else, like me, were curious about what is likely being referred to: https://www.forbes.com/sites/startswithabang/2016/05/20/when...


And here, I though you all were talking about the element of mercury, and how its mass is calculated from the 1s orbital using special relativity :)

https://blogs.scientificamerican.com/the-curious-wavefunctio...


Right, so we just added another required predictive ability to the more precise theory that will likely eventually supplant Einstein's. I don't see why that is at odds with what I wrote - no matter the outcome of the experiment, a new theory will need to also predict its outcome. But since Einstein's theory also did, we don't currently need to replace it for that reason (we do for other reasons, such as unifying quantum mechanics and relativity).


> we don't currently need to replace it

It‘s not about “replacing”: in all the areas where it is already confirmed it doesn’t ever need to be replaced. Wherever Newton’s formulas are good enough they are still used and are going to be used in future. It’s just about extending the limits. And in this case, again, Einstein’s formula are shown to be good enough.


Right, your point is that normally, new theories don't fully refute the existing ones - the existing ones turn out to be special cases of the new one - the old theories are not entirely wrong, but rather only right sometimes. Like how Newtonian physics work fine as long as things are not traveling very fast or are very heavy, at which point we need relativity. I fully agree with this. But being only right sometimes is still a falsification of the theory (as a complete theory to describe and predict all phenomena that it pertains to). My point is that nothing in my top level comment is at odds with this. Relativity has once again not been falsified. Newtonian physics have been falsified (in general - though they are contained as a special case within relativity). The body of evidence that a new theory needs to deal with in order to replace and subsume relativity has just been expanded even more - yay!


No. My points were simply:

1) it was not "an attack" at all but an experiment that confirmed the theory's validity in the limits of the Universe previously unreachable to humans.

2) The "replacement" didn't happen before with Newton's formulas: under the limits under which it was known that Newton's formulas worked before Einstein's it is still known that Newton's formulas work. The basic formulas still being taught about special relativity are actually Lorentz transformations, decades older than Einstein's work and still actively used under the limits where they still work etc. There isn't any "refutation" there it's about having most of the Universe explainable by the formulas we use. The new discoveries aren't "replacements" but "filling the blanks" which remain, and one more area is now confirmed not to be a blank at all.


You have no idea how correct you are on this. I have had to deal with multiple philosophy types who just knew that special relativity (rather than general in this case) could not be right and had a variety of "proofs" against it; key to their delusions was this misapprehension that Michelson-Morley had been done just one time only!

Dr. Clifford Will's Was Einstein Right? is a now-dated book about the various experiments over time, which is very handy if you want a summary of just how many attacks have been weathered. I don't doubt that it could use a second volume by now.


There's a famous book, never translated into English, titled Hundert Autoren Gegen Einstein or A Hundred Authors Against Einstein; of course, in Einstein's own words, had he been wrong, one would have been enough.

https://en.wikipedia.org/wiki/Criticism_of_the_theory_of_rel...


> the anti-science crowd latches on to things like this

Dark ages are built on anti-science sentiment but we have all the means to counter and disseminate science results these days, provided that discourses are made simpler enough (without being shallow) to inform the general public... we need more and better scientific communicators, then, that’s also why the small content project I am recently pushing over here too.


Being a better scientific communicator might mean being more aware of how innocuous statements can be accidentally or deliberately misconstrued.


In compiling booklets and summarizing references from all over the world, I am especially learning that less words is more clarity. Also, convoluted prose obfuscates results. It is also evident that some tones are purpotedly built on propaganda or limited span.


The anti-science crowd is going to be anti-science regardless of how science is reported.


That's misguiding and unproductive. Any group is made up of hard-liners and on-the-fence people, and hard-liners change too, just slower. Being dismissive is as damaging as misinformation.

Anti-intellectualism, anti-science, etc. will always attract some people to some degree. Within those constraints there's a world of difference.


The second paragraph seems to come across as a mere rephrasing of the exact sentiment the comment the first paragraph so passionately rebukes.

Care to dissuade me of this, because it seems like you’ve simultaneously concurred with the statement you’ve called misguiding and unproductive.


Here's a rephrase. You have to be understanding in order to positively influence people. Therefore, it's unproductive to be dismissive. Anti-scientific sentiment as phenomenon will not disappear, but will be shaped by that positive influence. It's misguiding to leave it at saying that the phenomenon will not disappear, because that implies that the groups in question are outside our influence.

Edit: if I'm still coming off vague, a sibling to my original comment says what I wanted to say more succinctly.


He's saying that there will always be anti-science people, but individuals who are anti-science will not always stay anti-science, so it is still worth putting in the effort to change their minds


Give it a chance. Question more why the comment is made that way. Not everyone is comfortable in communicating as you did there.


Are you suggesting we may not be in disagreement? I really think we are.


But good science teaching and reporting can make the anti-science crowd smaller and less politically influential than it would be otherwise.


Perhaps, but overcoming the audience's strong prior commitment to anti-science seems to be a tough haul.


Got any science to back that up?


Within their domain, scientific theories once discovered are true forever e.g., Newton's laws of motion are true for cases that are not too fast (special relativity limit), too small (quantum effects), too massive (general relativity limit).


> the anti-science crowd latches on to things like this

Truly fundamental misunderstandings are hard to correct.


> No it doesn't, it has a long, long list of wrong answers, and a short list of answers that haven't yet been proven wrong, which makes up our current best approximation of 'the truth'.

"So you're saying that science doesn't know anything, and therefore quantum vibrations homeopathy Reiki is just as real as General Relativity." Or something. My point is, the anti-science crowd will use anything it can, including lies, to "prove" that it's right and you're wrong.

The people who are so emotionally damaged they can't stand the idea that the universe might require effort on their part to understand will always find ways to misunderstand things. Trying to communicate with them is futile.


> 'Science is claiming to have all the right answers just as much as religion!'

lol what?!? who says that?!?


I suggest listening to the podcast "Oh No! Ross and Carrie" if you're interested in weird claims that people make.


Anti science people


Many pro-science people (including some well known science communicators) don’t need much encouragement to appeal to the ultimate authority of science. There was an HN thread on the munchausen trilemma a little while ago, full of people commenting on how intuitive it was, but absolutely unwilling to accept how it could impact their own beliefs in science.


That's because science is a distillation of consensus experience, not absolute truth.

That doesn't make it invalid, because the "experience" part really really matters.

But it means its validity is limited to "for all practical purposes" - which is perfectly good enough as a baseline, and certainly more useful than "It's just my opinion and I'm right about everything because I say so" or even "Because my god says so" or "I'm going to lose money if this turns out to be true, so I'm going to spend some money up front on a PR campaign to persuade people it isn't."


This video of stars orbiting Sagittarius A* taken over 20 years never ceases to blow my mind. https://youtu.be/DRCD-zx5QFA


Actually, the effect described here (if I am not mistaken), was already observed in the orbit of Mercury before the theory of Einstein explained it. See: https://en.wikipedia.org/wiki/Tests_of_general_relativity#Pe...


Yes, in many respects this is a non event. It is as expected based on what we have previously observed and tested. It is still worth looking at, however, as it would have been very interesting if the result were different.


Precession was also observed in binary pulsars, where the timings are much more accurately measurable. Still nice to get another confirmation in a novel regime.


Right, but the situation orbiting a black hole is more extreme than orbiting the Sun, so this is testing the theory more stringently than Mercury did.


Good point. Orbit is an orbit. "Don't just draw a full cycle of orbits to highlight it is some amazing finding"


Because the gravity is stronger in these cases it's possible that effects not captured by Einstein's theory could be seen, just as Mercury probed stronger fields, falsifying Newton's theory. But Einstein's theory survived this scrutiny.


In case anyone hasn't seen it here is the time lapse of stars orbiting Sagittarius A:

https://www.youtube.com/watch?v=TF8THY5spmo


From the article:

> One hundred years later we have now detected the same effect in the motion of a star orbiting the compact radio source Sagittarius A* at the centre of the Milky Way. This observational breakthrough strengthens the evidence that Sagittarius A* must be a supermassive black hole of 4 million times the mass of the Sun

I love that scientists are so careful about stating that something is absolute fact when they can't be 100% sure. The public's idea of things is definitely that Sagittarius A* is a supermassive black hole, but that compact radio source could be something else, so they're careful to note that.


Such an amazing experiment, it's incredible that we can measure such things at these distances with this level of accuracy. A shame we're more interested in our own opinions than the science.


Anybody know what the precession period is for Mercury and this star? How long does it take for the orbit to return to some starting orientation?


3 million years for Mercury, by my calculations and https://en.wikipedia.org/wiki/Apsidal_precession#Calculation


How does one with good math/physics background gain a deeper understanding of black holes? I'm fascinated by them and want to systematically learn the theory behind it.

My plan is to start with General Relativity and Einstein's equations, maybe some journal articles about black holes. Do you have any suggestions?


Watch some course lectures on Youtube. Work your way through some books such as by Schutz or Sean Carroll, or if you are brave by Misner, Thorn and Wheeler.


I walked past a guy standing outside the Palo Alto Creamery, and he was reading from a copy of Misner, Thorne, and Wheeler -- it's a very distinctive looking book. Turns out he was a guy with a non-math background who had taught himself enough to follow the book. I was impressed!


That book is big enough to visibly distort space-time on its own.

I'm impressed that the reader learned the math on his own. And, uh, what's my excuse?


I would also recommend "The Large Scale Structure of Space-Time" by Hawking and Ellis. It uses some advanced mathematics and some prior knowledge of GR, at least at the level of Schutz or Carroll, is needed, but it is a wonderful book to learn about the global structure of spacetimes with black holes, singularity theorems and so on.


Carroll is a graduate-level book, and MTW is notorious. I'd start with Hartle, or something even lower-level.


My undergraduate course used Schutz and Carroll. I think, as long as you are comfortable with both proof based and dirty mathematics, you can start with physics grad texts. In fact, a lot of times, the concepts are easier to understand with more conceptually elegant mathematics.


Make sure you have Special Relativity down pat beforehand, both intuitively and in terms of math.


Sun sheds light.

Black hole sucks light.


Probably easier to list number of times Einstein was wrong (it's not even a half dozen).

I hope I live long enough to see then use the moon for lensing or put radio/telescopes on the far side.


Ironically, one of these times is when he doubted the existence of black holes. Yes, it means the article could have been subtitled "proves Einstein wrong".

To be clear, while general relativity predicted the existence of black holes, Einstein initially thought that they wouldn't be able to form in reality. [1]

[1] https://www.jstor.org/stable/1968902


That's because he didn't publish until he was sure he was right. He said that 99 times out of a hundred, he was wrong.




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