sethoflagos

Which reminds me of the Keynesian multiplier: Acceptance of large scale homelessness is a political choice.

The Nightjar family are all pretty cryptic. Here's three from Nigeria. Long-tailed Nightjar - Caprimulgus climacurus sclateri Standard-winged Nightjar - Macrodypteryx longipennis Plain Nightjar (cinnamon form) - Caprimulgus inornatus

For many years, I leant strongly towards some form of non-analytic emergence principle to explain eg some of the wackier hypotheses of statistical mechanics that are simply not seen in classical mechanics, such as 'all the molecules of gas are in the corner of the box' type paradoxes. I'm tending to drift away from this as I see these paradoxes being due to a) crude over-simplification of statistical mechanics by some rather than a real fault in the method, and b) an increasing awareness that quantum phenomena significantly modify the assumptions of randomicity by the creation of 'forbidden zones' due to destructive interference. In particular, maximal quantum entanglement of the gas particles is often equated with the state of thermal equilibrium. This suggests that the system has shared memories of its recent particle collision history embedded within the affected fields, and if the Transactional Interpretation of QM has traction, then this memory extends at least a little into the future too. The upshot is that the molecules do not act independently of the bulk gas. And the bulk gas behaves accordingly. Quantum thermodynamics is a currently developing field that is attempting to address this. Perhaps the most appropriate methodology could be called 'holistic reductionism'? Is that an oxymoron?

The last ten years in particular has seen a major increase in concentration of global wealth into the hands of the 'haves' at the expense of the 'have nots'. (see https://www.worldbank.org/en/news/press-release/2021/10/27/global-wealth-has-grown-but-at-the-expense-of-future-prosperity-world-bank for a fairly tepid version of this) This has consequences. In particular, it causes an increase in the number of 'have nots' who have limited or no easy access to bathroom facilities, and seek some alleviation of their misery through intoxication. Who has created this sorry state of affairs? Do the miserable wretches enjoy their condition and willingly embrace their misfortune? Rather the OP seems to voice a total denial on behalf of the 'haves' for their greed being a major causative agent for the ills in society that are a natural consequence of their actions. One wonders whether the OP is one of the 'haves' or one of the 'has just slightly more than the have nots'. There are very clear historical precedents from which we appear to have learnt not enough.

Consciousness is a really poor example on which to make definitive pronouncements. You are speculating and inviting others to speculate on a phenomenon that fails to generate a commonly agreed definition and for which there is no even partially accepted physical model. A much better basis for discussion was offered by @joigus But you seem to be ignoring this post.

The OP has a lot in common with official policy of at least one leading democracy. Vilify and demonise a particular minority to sway the majority away from supporting progressive social policies toward them. Criminalise their very existence. Deny them proper and timely legal process to have their legitimacy assessed. 'Transport' them to the safe, caring comforts of Rwanda where they will be 'taken care of'.

It looks like one or more of the floating varieties of Sargassum. The controlling factor is I understand nutrient supply to the historically low nutrient Sargasso sea. And this was thought to be dominated by mineral dust carried by the trade winds off the Sahara. Most likely recent increasing influx of nutrients may be from ecological changes occurring in the Amazon system and possibly our neck of the woods in sub-saharan West Africa. Coupled as you say with locally significant shifts in surface currents.

You want me to yield to your opinion? It isn't me that's having a problem with established science. I suspect pride is clouding your judgment. Good night.

Only if you want it to be. Once dmB has been exhausted it plays no further part in rocket propulsion. I'm pretty sure I'm free to reset the counter back to zero again. The total amount of exhaust is of no relevance to the OP. So why bother keeping track of it.

Over the time interval dt, mB increases from 0 to dmB. So in context mB = dmB.

Ftotal = dp/dt = mdv/dt + vdm/dt = F1 - F2 = 0 For total system Consider momentum change of body A (rocket +unused fuel) FA = dpA/dt = mAdv/dt + vdmA/dt = F1 - F3 = X (non-zero!) Consider momentum change of body B (exhaust) FB = dpB/dt = d/dt (mB (v-(v-ve)) = d/dt (mB (v - ue)) = dmB(dv/dt - due/dt) + (v - ue)dmB/dt = dmBdv/dt + (v - ue)dmB/dt Since dmB = - dmA FB = - dmAdv/dt - (v - ue)dmA/dt = F4 - F3 - F5 = -X (non-zero!) Add FA and FB Ftotal = FA + FB = dp/dt = mAdv/dt + vdmA/dt - dmAdv/dt - (v - ue)dmA/dt = (mA - dmA)dv/dt + vdmA/dt - vdmA/dt + uedmA/dt = 0 Hence (mA - dmA)dv/dt = - uedmA/dt or F1 + F4 = F5 There's a couple of differences here to your thrust equation. I've used ue instead of ve to show that the exhaust velocity is specific to the comoving inertial reference frame of the rocket whereas v is for any observer. I've also left the dmA term in the left hand expression to emphasize that the thrust equation involves mA rather than m of the overall equation. Mathematically, it's justifiable to delete this dmA as is is overwhelmed by mA. Please take note how I have distinguished different forces with different subscripts. Much of your confusion appears to stem from an expectation that all Fs must be equal. Sometimes they are. Generally they are not.

It's hardly my field, but I'd been led to understand that quantum information behaved rather like entropy. ie that if it is erased from one part of the universe (requiring some form of work) at least as much must be released elsewhere. Perhaps I'm misunderstanding you.

I was thinking more generally than that. More 'every breath we take, every move we make' adds to the quantum information of the universe, albeit in a highly garbled form, but it's there for eternity.

You're absolutely right. There was no call for my response. I've no idea why I wrote it. Can we put it down to a senior moment?

I see you contributing quite frequently on climate change issues. Maybe it's a generalisation, but the impression that I get from your posts is that every little bit that we can do to reverse the current trend counts. No matter how insignificant our personal efforts may seem at the time. I guess I've a tendency to vote with my feet. I may not have much impact at the ballot box, but transferring my economic activity to a different country is probably more significant overall.

I lile these products. As do my wife and children. Why should we answer to you about our personal preferences? None of your business I think.

I watched a Youtube video tonight that pulled together a few lines of thought that I'd been pondering over without linking them together. What really grabbed me was the contrast between the fragility and improbability of complex civilisation with the indestructability of quantum information. Why such a visceral reaction to this? Well I've not taken part in any democratic process for over 25 years on the grounds of too much hassle; I don't live in the country where I could vote; my vote probably wouldn't make much of a difference anyway. And yet those decisions not to act, via the indestructabilty of quantum information, must have measurable consequences stretching out to the end of time. That's one hell of a long time for the butterflies wingflap to perturb the evolution of the universe. I'm seeing the epitaph on my tombstone. Seth 1958 - 2028 Did f*** all to defend his personal values Suddenly I'm drawn a lot closer to a POV often expressed by @Ken Fabian

I'm no expert in this but I'll say it anyway. My understanding is that in SR the spacetime interval between two events is invariant for all inertial reference frames. The minimum spatial separation occurs for the observer who sees the events as simultaneous. All other observers see a greater spatial separation and an increasing temporal separation per s2 = x2 + y2 +z2 - (ct)2 = constant. Local clocks and measuring rods must vary accordingly.

I've just done it. According to your earlier definition: A more interesting question would be to ask "How was the exhaust decelerated from v to v - ve?" One for another day perhaps.

Yes, mdv/dt = -vdm/dt is indeed the overall force balance. So let's separate rocket from exhaust components. Consider an observer travelling with a constant velocity v He sees the rocket of mass m gain a velocity dv. He sees a small amount of mass dm ejected at a velocity of ve in the opposite direction No nett motion of the total becomes mdv = -vedm Hence we recover your thrust equation mdv/dt = -vedm/dt It really isn't rocket science ..... er 🤨

Someone gives you $5. Someone takes $5 off you. You are left with $0. Someone gives you $5. Someone takes $5 off you. You are left with $0. Neither did I mention that integration of the equation yieds the Tsiolkovsky rocket equation. The OP didn't ask for it. But you can mug up on it at https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation

So? What is omitted that is pertinent to your OP?

dp/dt gives you BOTH sides of the equation dp/dt = d(mv)/dt = mdv/dt + vdm/dt =0 Hence: mdv/dt = -vdm/dt

edit: deleted

I'm inclined to see even this as a false dichotomy. I like Aristotle's ancient maxim: 'Nature operates in the shortest way possible'. It keeps coming back in various guises: the various statements and restatements of Occam's Razor; Principles of Parsimony and Least Action; even the simple symmetries underpinning the Standard Model. In context, it is indifferent to any concept of supernatural being. Why should a principle that frames much of your core opinions be framed in terms of something you've rejected? Do we label modern chemists as 'antiphlogistonists'? At some stages in our development, explanations involving supernatural beings were the simplest and therefore the best explanations going. But we have better explanantions available to us now and are able to discard some of the more elaborate beliefs of our ancestors. So like @Genady I find the term 'atheist' unhelpful though I stopped believing in fairies nearly 60 years ago. I feel the term is maintained in the interests of those who wish to keep an outdated concept centrestage. Time to move on.