Well, if you want a simple argument from authority, John Carlos Baez's confirmation that she's right is pretty good. If you want a better one, she very rarely gets any of her facts wrong.
Now let's go point by point.
Is Carlo Rovelli fine with it not being testable, in that he is fine with research continuing even though it can not be tested with up coming experimental set ups? He is arguing for a version of the theory that can't be tested, is continuing to do research on it, and presumably thinks that he is doing science.
If Sabine was going to expose howe much money was going to these topics and where it could be better spent that would be worth watching. Discussing how these things wind up getting funded would be a very different video. And would not likely be interesting to most of her audience.
Or is Carlo Rovelli ok with the theory being unfalsifiable in the sense that that he is ok with the research not being science? Presumably he thinks that he is doing science. Sabine's opinion clearly is that this isn't really science. However she only claims her opinion as her opinion, not established fact.
Ok what percentage and total amount of founding is going to this? Again, that would be a very different video. In 10 minutes for a general audience, you have to make decisions about what you will and will not cover. It's not a valid criticism of her that she made a choice. Particularly in a video that she disclaims as a personal rant.
Arguments saying loop quantum gravity require space to be quantized, but they can not be lorentz invariant without having the quantization go to zero volume, according to Sabine, and no one has done that and extracted back out loop quantum gravity. This is not according to her, this is according to an argument that comes from Lee Smolin. A region of space that has a specific amount of area will, according to special relativity, have a smaller area according to an observer that is traveling fast enough. By having the velocity as close as you want to C, you can make the area arbitrarily small. So your choice is to violate Lorentz invariance, or have arbitrarily small areas. If you violate Lorentz invariance, the speed for light will depend on the wavelength.
As her previous video at https://www.youtube.com/watch?v=ZlHvW6k2bcM said, this prediction of Lee Smolin has been tested to extremely high precision, and the predicted effect was not seen. That version of LQG has been falsified. The alternative supported by Carlo Rovelli is that you need to average out over quantum areas in all reference frames. This is a neat idea, but in several decades, nobody has made it work. Until someone can make it work, LQG can't produce any testable predictions.
Please note that John Baez, who worked on LQG for 10 years, specifically complimented her presentation of this particular issue. Her description of where research stands is accurate.
I am experimentalist and this is not my area. I would want to see a link to a paper/book etc. Rants generally do not come with properly cited references. That said, the previous video that this refers back to is based on https://arxiv.org/abs/2402.06009?utm_source=substack&utm_med..., which is one of the experimental tests showing that Lee Smolin's prediction is false.
The analogy to the angular momentum operator comes off as a good place to start investigation/research but is treated dismissively, anologies like this often do not apply in the end but can still be useful. It was a good place to start. After 20 years of research that has failed to turn that idea into anything workable, most people would conclude that this is an analogy that will not apply in the end. But apparently Rovelli gets mad at anyone who doubts that it will work out. One of the triggers for this rant was whatever Rovelli said to her in private. Personally, I excuse her for being human here in her reaction.
Ok that does not seem like the gottcha that it is laid out to be. Interesting stuff happens where their are apparent contradictions in physics. No, it really is the gotcha it claims to be. It's directly inside of the math. This demonstration is no different than, say, proving that sqrt(2) is irrational by proving that if you start with the smallest fraction that equals it, you can find a smaller one.
The conclusion of that gotcha is exactly what she said: if there's a minimal area then you can't have Lorentz invariance. And conversely, if you have Lorentz invariance, then you can't have a minimal area. Experimentally, we have tested for the Lorentz invariance to be expected from a minimum area based on the Planck length. It does not exist. And therefore there isn't Lorentz invariance.
Why did Sabine talk about it being a mathematical contradiction if you can make the theory work, but it leads to physical phenomenon that we do not observe? Her previous video (that triggered the nasty emails)_made this point more clearly. She's saying that there is a mathematical contradiction between having minimal areas and Lorentz invariance. This forces us to choose to have one or the other. Minimal areas leads to a testable and now falsified theory. Lorentz invariance has yet to lead to a theory that doesn't blow up with unnormalizable infinities, let alone one which can produce a testable prediction.
I can not make those two arguments jive in to a cohesive whole. Not that it can not happen, but I can not from this video and that is the conclusion, or similar, I normally reach when watching Sabine's videos and why I do not watch or recommend them generally. Is that Sabine's fault, or yours? This video is much lower quality than her normal ones. And yet absolutely none of what you think are flaws, do I think is one. Every one of your objections has an answer that jives. And the conclusion is agreed with by John Baez, whose background on this specific topic is much stronger than yours.
Perhaps, rather than looking for things to complain, you should try figuring out what she actually said. In my experience it is logically internally consistent. Even though it skewers some sacred cows.
> Well, if you want a simple argument from authority, John Carlos Baez's confirmation that she's right is pretty good. If you want a better one, she very rarely gets any of her facts wrong.
It is not what I want. I read the linked comment by John Carlos Baez[1] and do not agree with the wording of your conclusion "that she's right". There is some alignment, but you have removed any nuance.
> Again, that would be a very different video. In 10 minutes for a general audience, you have to make decisions about what you will and will not cover. It's not a valid criticism of her that she made a choice. Particularly in a video that she disclaims as a personal rant.
My specific comments are about why I do not find value in Sabine's video not about not about a general audience. The over all arch is a point that I do not find her videos or the discussions in the comments valuable on hacker news in response to Dang's comment:
> so I think we can give this thread a second chance
[2]
So my comments are not about how she decides to reach her general audience.
I think this covers some of your pervious comments too.
> This is not according to her, this is according to an argument that comes from Lee Smolin.
"What I said in my pervious video" is what she said in her video. So this idea may not have originated from her, but my word choice is correct by saying according to her. This does no assert she came up with the idea or is 100% sure of it.
> A region of space that has a specific amount of area will, according to special relativity, ...
> ...
> Please note that John Baez, who worked on LQG for 10 years, specifically complimented her presentation of this particular issue. Her description of where research stands is accurate.
My comment about about the video and why it is not useful to me or useful seeing it on HN, not about the correctness or incorrectness of Sabine's statements which is what you seem to be addressing here.
> It was a good place to start. After 20 years of research that has failed to turn that idea into anything workable, most people would conclude that this is an analogy that will not apply in the end. But apparently Rovelli gets mad at anyone who doubts that it will work out. One of the triggers for this rant was whatever Rovelli said to her in private. Personally, I excuse her for being human here in her reaction.
You are making some assumptions here and empathizing with Sabine, which is understandable. Arrogant Physics professor gets mad when someone questions their pet theory is not unrealistic but is not headline worthy either. Does it matter if he was mad? Is this any different than any other celebrity spat? If not, that is not what I read HN for.
> Rants generally do not come with properly cited references.
I know it was a rant, I saw the labeling. That does not help make it good material for HN or lead HN commenters to interesting and curious comments though. The reverse is often true regardless of the source of the rant.
> No, it really is the gotcha it claims to be. It's directly inside of the math. This demonstration is no different than, say, proving that sqrt(2) is irrational by proving that if you start with the smallest fraction that equals it, you can find a smaller one.
Physics is not practiced like math though, so it is different. A contradiction in physics theories is not the same as saying true = false in math. Experimental evidence and observation rule the day until we find the fundamental laws of physics, after that it will be more like math(well at least some physics will).
> Her previous video (that triggered the nasty emails)_made this point more clearly. She's saying that there is a mathematical contradiction between having minimal areas and Lorentz invariance. This forces us to choose to have one or the other. Minimal areas leads to a testable and now falsified theory. Lorentz invariance has yet to lead to a theory that doesn't blow up with unnormalizable infinities, let alone one which can produce a testable prediction.
Comments like this, and much of what you said before this, lead me to think Sabine's pervious video would be less likely to cause me to write a comment like I did.
> Is that Sabine's fault, or yours?
Nothing I have said is about Sabine being at fault of something. I can stand corrected if something I wrote was too misleading though.
> This video is much lower quality than her normal ones.
This seems like it would argue against Dang giving this Sabine video an exception.
> Perhaps, rather than looking for things to complain,
That is not what happened here. My response was to Dang about giving this video a exception and the comment on "sensational style".
> you should try figuring out what she actually said.
And if I was having a conversation with Sabine or if I was corresponding with her then both people are responsible for reaching out to cover any communication gaps. That is not what this is, this was Sabine's rant as labeled by her and you.
> Even though it skewers some sacred cows.
I do not think Sabine's videos "skewer sacred cows". At least not any in the physics community at large, maybe some sub disciplines. The physic's community at large does not seem to have many if any sacred cows, that is my experience at least.
Your complaint is that it is hard to extract truth from her videos.
However extracting truth from what you said is trivial if you believe that what she reports as fact, is fact. And what she reports as her opinion, is her opinion. If you pick any 5 videos you want, I'd be happy to help you spot check them. Just like I did with this one.
Now I'd like to pull out three specific issues.
1. Your point about settling physics with experiment is not applicable here. The result is about what the math will predict if you make a specific assumption in a specific mathematical model. Testing that is like trying to test the frequency with which 1+1 gives you 3. It's a question of logic. What becomes a question of experiment is whether a particular model is a good description of reality.
2. She may not be skewering cows that are sacred to all of physics. But a lot of her videos skewer cows that are sacred to some group, and she's constantly getting an earful about it.
3. Why this video? The reason why I voted for it was not quality, but topic. I think it is very important to be aware how easily branches of science become pseudoscience. And with John Baez' support, it's clear that her complaint is more than simple sour grapes. See https://news.ycombinator.com/item?id=41808404 for some of my thoughts that are specific to this topic.
> Your complaint is that it is hard to extract truth from her videos.
>
> However extracting truth from what you said is trivial if you believe that what she reports as fact, is fact. And what she reports as her opinion, is her opinion.
So the level of doubt and or critical thinking I apply to Sabine's videos is not much different than what I would apply to a physic paper out of journal and I feel like I can often apply less than what I apply while reading many popular science articles. That is no where close to the level of trust I would put in to a well grounded physics text book though.
This sort of doubt is critical to most people while reading journal articles, double checking, verifying, not assuming ground truth for what a paper says to uncover hidden assumptions, mistakes, and differing interpretations.
~"Just believe" is not conductive to learning science and is not going to make for curious or simulating conversation.
> If you pick any 5 videos you want, I'd be happy to help you spot check them. Just like I did with this one.
You did not extract the value from this video though. You reference other resources to try and get the value. I am not interested in doing something similar with her other videos.
> 1. Your point about settling physics with experiment is not applicable here. The result is about what the math will predict if you make a specific assumption in a specific mathematical model. Testing that is like trying to test the frequency with which 1+1 gives you 3. It's a question of logic. What becomes a question of experiment is whether a particular model is a good description of reality.
If physical reality does not, can not matter to resolving a question, your question may not be about physics. This one point is not enough, like I said original, by itself, to make the apparent contradiction obviously non interesting.
> 2. She may not be skewering cows that are sacred to all of physics. But a lot of her videos skewer cows that are sacred to some group, and she's constantly getting an earful about it.
Is the earful about any sacred cows though? Are their other viable explanations You may have evidence for you conclusion, but it is not here.
> I think it is very important to be aware how easily branches of science become pseudoscience.
Sabine asserts this has happened to quantum loop gravity but doe snot show it. If I thought what she said was true and I wanted to make convincing case I would have to go out and do considerable research and put together a case, I could not simply reference this video.
> And with John Baez' support, it's clear that her complaint is more than simple sour grapes.
Sour grapes normally means that when someone can not have something they want they go negative on it instead. Does this saying even apply here? Nothing in the video made me think she was sour about anything.
My lengthy comment was not about value extracted in this video, it was addressing your doubts about the information in it. I personally got value from the subject of the video itself. Which we did not discuss.
It really appears to me that you weren't trying to address any value. What you describe as critical thinking was merely searching for ways to object without thinking too hard about whether it was a fair objection. As an example I point to your failure to follow the trivial mathematical argument saying that LQG models either have to accept that there is no lower bound on quantized area, or that they violate Lorentz invariance. You kept trying to insist that this sounded like she was contradicting herself (she wasn't), and this argument should be resolved by some sort of experiment.
If this is truly the critical thinking that you take to research papers, you're probably not doing nearly as good a job of reading them as you imagine. Meanwhile, back in the real world, I make a habit of attempting to figure out how trustworthy and well-informed each source is. And how objectively they report on what they think that they know. I'm extremely pleased with Sabine. She's very careful to only report as fact things which are true. She's willing to express opinions with no regard to who will agree or disagree. And she's clear on the difference between her knowledge, opinion, and speculation.
Because of this, I've learned to trust her claims on things that I can't independently verify. Her personal reports on the behavior within LQG is of interest to me. The independent confirmation from John Baez, who I've known for years, trust, and has a completely different point of view, makes her description extremely trustworthy. Her claims on that topic are not something that I can independently verify other than to decide which primary sources I trust. And I've learned to trust both Sabine and John.
Now let's go point by point.
Is Carlo Rovelli fine with it not being testable, in that he is fine with research continuing even though it can not be tested with up coming experimental set ups? He is arguing for a version of the theory that can't be tested, is continuing to do research on it, and presumably thinks that he is doing science.
If Sabine was going to expose howe much money was going to these topics and where it could be better spent that would be worth watching. Discussing how these things wind up getting funded would be a very different video. And would not likely be interesting to most of her audience.
Or is Carlo Rovelli ok with the theory being unfalsifiable in the sense that that he is ok with the research not being science? Presumably he thinks that he is doing science. Sabine's opinion clearly is that this isn't really science. However she only claims her opinion as her opinion, not established fact.
Ok what percentage and total amount of founding is going to this? Again, that would be a very different video. In 10 minutes for a general audience, you have to make decisions about what you will and will not cover. It's not a valid criticism of her that she made a choice. Particularly in a video that she disclaims as a personal rant.
Arguments saying loop quantum gravity require space to be quantized, but they can not be lorentz invariant without having the quantization go to zero volume, according to Sabine, and no one has done that and extracted back out loop quantum gravity. This is not according to her, this is according to an argument that comes from Lee Smolin. A region of space that has a specific amount of area will, according to special relativity, have a smaller area according to an observer that is traveling fast enough. By having the velocity as close as you want to C, you can make the area arbitrarily small. So your choice is to violate Lorentz invariance, or have arbitrarily small areas. If you violate Lorentz invariance, the speed for light will depend on the wavelength.
As her previous video at https://www.youtube.com/watch?v=ZlHvW6k2bcM said, this prediction of Lee Smolin has been tested to extremely high precision, and the predicted effect was not seen. That version of LQG has been falsified. The alternative supported by Carlo Rovelli is that you need to average out over quantum areas in all reference frames. This is a neat idea, but in several decades, nobody has made it work. Until someone can make it work, LQG can't produce any testable predictions.
Please note that John Baez, who worked on LQG for 10 years, specifically complimented her presentation of this particular issue. Her description of where research stands is accurate.
I am experimentalist and this is not my area. I would want to see a link to a paper/book etc. Rants generally do not come with properly cited references. That said, the previous video that this refers back to is based on https://arxiv.org/abs/2402.06009?utm_source=substack&utm_med..., which is one of the experimental tests showing that Lee Smolin's prediction is false.
The analogy to the angular momentum operator comes off as a good place to start investigation/research but is treated dismissively, anologies like this often do not apply in the end but can still be useful. It was a good place to start. After 20 years of research that has failed to turn that idea into anything workable, most people would conclude that this is an analogy that will not apply in the end. But apparently Rovelli gets mad at anyone who doubts that it will work out. One of the triggers for this rant was whatever Rovelli said to her in private. Personally, I excuse her for being human here in her reaction.
Ok that does not seem like the gottcha that it is laid out to be. Interesting stuff happens where their are apparent contradictions in physics. No, it really is the gotcha it claims to be. It's directly inside of the math. This demonstration is no different than, say, proving that sqrt(2) is irrational by proving that if you start with the smallest fraction that equals it, you can find a smaller one.
The conclusion of that gotcha is exactly what she said: if there's a minimal area then you can't have Lorentz invariance. And conversely, if you have Lorentz invariance, then you can't have a minimal area. Experimentally, we have tested for the Lorentz invariance to be expected from a minimum area based on the Planck length. It does not exist. And therefore there isn't Lorentz invariance.
Why did Sabine talk about it being a mathematical contradiction if you can make the theory work, but it leads to physical phenomenon that we do not observe? Her previous video (that triggered the nasty emails)_made this point more clearly. She's saying that there is a mathematical contradiction between having minimal areas and Lorentz invariance. This forces us to choose to have one or the other. Minimal areas leads to a testable and now falsified theory. Lorentz invariance has yet to lead to a theory that doesn't blow up with unnormalizable infinities, let alone one which can produce a testable prediction.
I can not make those two arguments jive in to a cohesive whole. Not that it can not happen, but I can not from this video and that is the conclusion, or similar, I normally reach when watching Sabine's videos and why I do not watch or recommend them generally. Is that Sabine's fault, or yours? This video is much lower quality than her normal ones. And yet absolutely none of what you think are flaws, do I think is one. Every one of your objections has an answer that jives. And the conclusion is agreed with by John Baez, whose background on this specific topic is much stronger than yours.
Perhaps, rather than looking for things to complain, you should try figuring out what she actually said. In my experience it is logically internally consistent. Even though it skewers some sacred cows.