joigus

“There are more things on heaven and earth, Horatio, than are dreamt of in your philosophy” comes to mind...

Why? Because no one knows what it is? I would agree that it's not very useful to think of dark energy in terms of mass, but what principle of physics are you invoking here?: No one knows what something is, therefore it can't have mass?

I think you come across as a deep observer of Nature. When we've disagreed, it's always been constructive and enriching. So thank you too!

Or perhaps a pothos leaf?

They are a family of paleoantropologists; Louis and Mary Leakey, as well as Richard's wife, Meave. Richard Leakey was an out and out field scientist. He was raised in the African savanna, rather than an academic environment. Neither he or his parents, probably, changed the big picture of the evolution of Homo sapiens by themselves. Although his father, Louis, is credited with having found a fossil that nobody knows where to put, Homo habilis. They mostly dug the ground, described what was there, and kept looking. But they were people who knew the environment inside out. R. Leakey was very involved in wildlife management and conservation strategies too. Very interesting people all of them. Here's a sample of what Richard Leakey was. Attenborough, Dawkins, Goodall, and Leakey discussing strategies to "save the planet." (2005.) The Selfish Green: IMHO, the contributions of Goodall and Leaky are priceless, and invaluable in their effort to tie these other two great minds to the ground, if I've understood them correctly. "It's very much part of being a primate, and the whole business of being a primate is to get other primates to do what you think is right" --Richard Leakey

https://www.theguardian.com/science/2022/jan/02/fossil-hunter-richard-leakey-who-showed-humans-evolved-in-africa-dies-at-77?utm_source=dlvr.it&utm_medium=facebook&fbclid=IwAR1PhZqET2nyh3CUhPbAvWs63MVs4l5o5mEP2j6bbH6iEqYIPvmCararT5w Sorry about the bad news. An excerpt of his book with Roger Lewin, Origins Reconsidered, is forever etched in my memory, where he paints a vivid picture of a young Homo erectus dying, and slowly, through more than a million years, becoming the fossil he and Alan Walker discovered at Lake Turkana, and forever after called the Turkana boy: This image of a wait-a-bit thorn springing from what once was a boy's head I find bordering poetry.

Very nice account, very informative, and very clear. Thank you. A simple calculation involving Boltzmann's constant gives you a temperature of a couple thousand Kelvin. Dividing 178000 J by Avogadro's number, and further dividing that by Boltzman's constant produces about 2141 K to break the bonds regularly. So no wonder there's a lot of it about. Breaking sigma bonds is not at all like breaking dipole-dipole hydrogen bonds, as in making water vapour... Does that make sense?

Very interesting. Thanks. My intuition is that the feeblest temperature background would split this tiny little weirdo of a molecule...

Whining won't make any of your 'proposals' more compelling. Denying evidence is not a good idea either. And ignoring the maths --the fact that non-linear equations are generally impossible to solve-- is not the solution. Don't know what to make of the attempt to trash one of the most brilliant physicists in living memory.

A mechanism can only be proposed once you have a theory. At least in physics and chemistry. I've told you in another thread, but you didn't answer. Newton's laws of motion don't come from a mechanism Maxwell's equations of electromagnetism don't come from a mechanism Einstein's equations of gravity don't come from a mechanism And so on. In the case of cosmology, the big bang is an inevitable consequence of Einstein's equations plus reasonable --and observationally sound-- cosmological hypotheses (cosmological principle, Hubble's law...). When extrapolated backwards in time, an expanding universe leads to a time in the remote past when everything was much, much closer together. There's your bang. Seems to make sense, doesn't it?

My sarcasmometer is going through the roof!

You're right if what you mean is that there are physical reasons to reject those solutions: A static universe would be unstable. But solutions they are. Einstein looked for that, and found it, because he had the prejudice of a static universe. In fact, the whole reason why he introduced the cosmological constant is precisely because it allowed him to tailor-make the universe as static. He did find that solution, but it's a freak universe. Then he regretted that he could have found the expansion of the universe as the biggest blunder of his life. Or so the story goes.

Some hopefully helpful ideas much related to what @studiot and @beecee have told you: Explaining a phenomenon via a mechanism: A well-established theory is already there that should explain the phenomenon, simply because it's its job to do so. Example: Rayleigh scattering (mechanism) and Maxwell's equations (fundamental law) explain why the sky is generally blue, but red during the sunset, or the other way around in Mars. Example: Light turning redder and redder the farther away from you it comes from in the sky. Non-examples: Accelerated expansion of space, entropy of black holes, existence of different families or generations of (quark, lepton) in the standard model of elementary particles. We know they can be accomodated in the laws easily. But we haven't the faintest idea why they should be there. It would be just as easy to plug in contraction of space, or just no expansion or contraction at all; there could be several models of what's inside a black hole that gave the same entropy for all we know; there could be just one family of (quark, lepton) or 3, or 103. Why not?

I think you're spot on with this. I haven't seen the movie, so I can't opine. Here's an updated version of it, very relevant today, which you may consider taking into account:

Other questions that make the argument very little compelling, if at all, are: how do we define civilization? Do we all belong to the same 'civilisation': Sumerians, Etruscans, Egyptians, and so on? It has been argued that civilisation defined by cities, writing, and monumental architecture, came about as a consequence of the end of a glaciation. Civilisations in a narrower sense like, e.g., the Minoans, probably disappeared because of a volcanic eruption. Others, like the Egyptians, because of people from the seas invading lands that were essential to their trade; as to the Mayas, it's debatable, but climate change may have played a role. It could also be for internal reasons... Earthquakes, meteorites, you name it. I concur with @MigL that there are too many unknowns. Also, I know you pitched this topic for applied mathematics, but we should try to make these ideas falsifiable, because we're concerned with science. You cannot experiment with civilisations as a subject of study in real time. (My emphasis) This is funny, because --and I think it's happened before-- you've made a good argument, but it seems to me that it works against your idea. How can we surmise that probability distribution? On other threads I've argued that the word 'random' in itself doesn't mean much. You would have to make a statistical hypothesis => probability distribution. Equiprobability doesn't apply in general.

There you go. That doesn't mean Claudio must be wrong. It's mostly a problem of it being or not being enough for other scientists to drop what they're doing and focus their attention on the idea. I can guarantee you that if you're a scientist, and they present you with a theory that really cuts it, you'll be paying outmost attention to it. In the meantime, nice words to your friends --maybe a little over-the-top encouragement-- doesn't do much harm.

I have to confess I'm out of touch with this thread. The only thing I'm saying is that the last attachment is but a show of mutual affection between Arturo Tozzi and Claudio Messori. Nothing more. I see no scientific arguments displayed there. That's all I can say, honest. Now that I've reminded myself of what the whole thing is about, I stand by what I said. Even great scientists can be highly susceptible to ideas from the periphery that seem to strongly support theirs. Scientists are human, you know. I have serious doubts that QED can shed any light on cognitive processes in any far-reaching way. The most I can fathom, as it stands, is that renormalisation schemes have something (vaguely) to do with the fact that what we wish to know about a physical system deeply affects how the system responds. From that to a theory of mental processes, it takes a long stretch of the imagination, and is dangerous territory --as both theories stand. Again, that's all I can say.

About the dialog between Claudio Messori and Arturo Tozzi? That they should get a room.

Just a couple of comments to add (and without getting into Hessian traces and eigenvalues .) The centrifugal term scales like v2, and the Coriolis term scales like vr(v). So it's, in principle, within our control to set that value (a low-enough orbiting speed) such that the line of instability can be controled by means of appropriately-gentle thrusts. At least that's what my physical intuition tells me. We must all learn to think in 3D!!! I spend hours on end on 1D. Happy New Year.

Yeah it seems that L1, L2, L3 are all saddle points: Very interesting. There's a part of it I can follow; other parts, like the stability conditions on the Hessian, which make sense to me but go over my head too. This is quite advanced Newtonian mechanics, and I don't think all of it can be safely done without computers.

Good call. I'm not sure. In the reference that @beecee provided, they say it requires relatively little thrust to keep it in orbit. If it's a very gentle saddle... What the technical reasons are, I don't know. Based on this, I'm assuming little fuel needs to be spent in order to keep it in orbit. The only thing I'm sure about at this point is that it's not going to be there forever.

Maybe not a peak, but a saddle point. A saddle point would be unstable too. I studied this ages ago, and I don't remember. Wikipedia: It's as @beecee says. Apparently you need some thrust now and then to keep it in orbit.

From 19.45 to 22.04: https://www.youtube.com/watch?v=r-L690pQhuo Here's a transcription of what Smolin says, *Does it matter that we let go of the attempt to pursue a concept of objective reality/objective truth. It's clear that's what Smolin is talking about if you rewind the video 30 seconds or so from where I've transcribed. It's very clear to me that Smolin is concerned that giving up on a concept of objective reality, when wielded by political minds, can turn into an excuse for 'everything goes'. It's nothing to do with elite scientists thwarting young, creative scientists when/if they're trying to push their ideas forward.