Genady

Sorry, but this is one of the specific cases where Newton gravity just can't answer the question, but GR can: gravitational effects of an infinite mass distribution. What it means is, that applying Newton in such cases can give a variety of contradictory answers, depending on how you want to calculate a diverging integral.

His book, Naturalist by Edward O. Wilson, was a required reading when I studied Biology. I liked it.

Thank you. Just wanted to clarify this.

Yes, I completely agree. There is one thing left unanswered still, on the next level up rather then down the scale. This scheme explains a helix that polyps make around the tube that they grow on, but it does not explain yet the helix that the tube itself presents to us.

That's correct. There is a theorem that any BH is entirely defined by these three parameters: its mass, charge, and angular momentum. Dark matter falling into a BH would increase the BH mass, but would not be detected otherwise as it doesn't radiate. BTW, we can talk about "flowing into" BH, but not about "passing the event horizon", because nothing ever can be observed passing the event horizon, by an external observer.

Are they thought not necessarily to interact via the weak interaction, or certainly not to interact via the weak interaction?

Ah, I see what you mean. But the baby coral doesn't grow radially but tangentially to the cylinder surface. Here is a scheme (borrowed from the circular polarization of light.) As you move along X, each arrow, representing next baby polyp, is tilted to the right. The result is right-handed helix. (My previous image was only to illustrate a budding process in general, nothing to do with my suggestion.)

For some reason I can't see the attached image. I think what you said is not correct. When you look outside from the cylinder's central axis, you have right and left well defined regardless of your orientation. (And the baby polyp is attached to the outside of the cylinder.)

Here is how I reformulate the puzzle to make it clearer without, hopefully, pushing a specific way of solution: Let's say, the apples are marked and their weights are x1, x2, ... . He takes out the apple #1 and finds that, e.g., x2+x5+x9... = x3+x4+x6... Then he puts the #1 back, takes out #2, and finds that x1+x7...=x3+x4... Etc. 17 times. Each side of each equation has 8 apple weights in it. We are asked to show that x1=x2=x3...

@TheVat I was thinking in the same direction and got an idea of where the chirality leading to that byproduct could start. Although the body of polyp is radially symmetrical, the budding process is not. See illustration below. This provides an opportunity to make a "one-sided liver", like in the @joigusexample above. If the genetic instructions of this coral cause a baby polyp to be a bit tilted say to the right, the next clone will be tilted again to the right, and so on, and voila, we get a helix with the specific chirality. Thanks a lot for the contributions!

A bit OT here: @joigus I also wish experts would contribute, but I didn't have a good experience with them. I emailed a few when this was fresh. Two replied. One just said, they never noticed such a pattern. The other said, they think I am wrong and the corals turn either way. They even attached a few pictures. Guess what? On all the pictures the corals were right-handed! This expert perhaps is a good biologist, but there is some issue with 3D geometry there In fact, they don't cluster thickly - there is half-meter or more between the loops and they don't bend easily. When there is some current, the entire thing just bends the other way, like a windsock.

That is what they can't do. They are radially symmetrical miniature upside-down jellyfish.

I got an idea. Firstly, we can assume that the polyps can chemically sense their neighbors. This thing is quite common and I think such an assumption is safe. Let's call it, Assumption 1.0. Secondly, let's assume that they are programmed by their genes to grow in such a way as to minimize interference with their neighbors in a given neighborhood. This is good for filter feeding. Let's call this, Assumption 2.0. Such a program will lead them to make a linearly arranged colony. This seems like a promising beginning. Now, how do we modify these assumption and add to them to get eventually to the right-handed helix?

I think, my main point of curiosity in this phenomenon is, how these small organisms, each a few mm across and apparently radially symmetrical, genetic clones of each other, determine uniquely a global morphology of the structure 1000 times larger than themselves. Perhaps, it is an emergent feature, but how?

One more piece of information. I've tried to compare my local findings with a global "data" by googling "wire black coral" images. As far as I could identify Cirrhipathes leutkeni in random pictures, I've found all of them right-handed as well. Thank you. I took time to read about them about 10 years ago. Yes, building up of an organism is programmed by genes and their is a strange correspondence between the linear order of these genes on DNA and linear order of body parts of bilateral organisms. However, as far as I remember, in didn't have anything to do with chirality. Plus, coral we discussing is not an organism but a colony of organisms. Plus, it is not bilateral.

It is hard for me to see a chain of causal connections between chirality on molecular level and chirality of a large scale morphology not even of organism but of a colony of organisms. The water here and specifically on that depth is practically still - the movement of about 1 cm/s or less. "Black corals" belong to so-called soft corals. They don't have calcium carbonate skeletons. Their "housing" is made of hardened mix of minerals and proteins. Coriolis effect doesn't appear on such a small scale. Here I have a story to tell. Six years ago I was in Ecuador and visited the Middle of the World, where they have equator line marked on the ground. The guides there gave a bunch of various presentations including the famous one with a water rotating opposite ways while being flashed. They had a tab with a hole, put it on one side of the equator, poured water from a backet and it rotated clockwise. They then relocated the tab to the other side of the equator, poured water - and it rotated counterclockwise. 'Coriolis,' they said. After the presentation I took one of the guides aside and tell her that I know that Coriolis has nothing to do with this and asked her to tell me the secret. She did. The sense of rotation is determined by which side of the hole they pour water to.

Here is a description including its distribution. Not in Kiribati. Correct, the reproduction is not an issue for corals. A few dozens of them are all I could find where I dive. Marine Species Identification Portal : Wire coral - Cirrhipathes leutkeni (species-identification.org)

Happy to answer all specific questions: The size of the locale is a couple of dozens mi/km. Depth about 100+ft /30+m. No strong currents, mostly no currents at all, certainly no prevailing currents. Orientation varies - around the island and along a curved shoreline. The location is practically on equator, about 12N, between the hemispheres

More specific situation, for example: if a satellite is held at rest with respect to Earth, it will certainly experience acceleration. While if it free falls toward Earth, the Earth free falls toward it, and both feel nothing. I'm sure your opinion will change after learning GR. Here is how Penrose - who knows something about gravity - describes the situation: Previously, an inertial motion was distinguished as the kind of motion that occurs when a particle is subject to a zero total external force. But with gravity we have a difficulty. Because of the principle of equivalence, there is no local way of telling whether a gravitational force is acting or whether what ‘feels’ like a gravitational force may just be the effect of an acceleration. Moreover, as with our insect on Galileo’s rock or our astronaut in orbit, the gravitational force can be eliminated by simply falling freely with it. And since we can eliminate the gravitational force this way, we must take a different attitude to it. This was Einstein’s profoundly novel view: regard the inertial motions as being those motions that particles take when the total of non-gravitational forces acting upon them is zero, so they must be falling freely with the gravitational field (so the effective gravitational force is also reduced to zero). Thus, our insect’s falling trajectory and our astronauts’ motion in orbit about the Earth must both count as inertial motions. On the other hand, someone just standing on the ground is not executing an inertial motion, in the Einsteinian scheme, because standing still in a gravitational field is not a free-fall motion. To Newton, that would have counted as inertial, because ‘the state of rest’ must always count as ‘inertial’ in the Newtonian scheme. The gravitational force acting on the person is compensated by the upward force exerted by the ground, but they are not separately zero as Einstein requires. On the other hand, the Einstein inertial motions of the insect or astronaut are, according to Newton, not inertial. Penrose, Roger. The Road to Reality (pp. 393-394). Knopf Doubleday Publishing Group.

Gravitational acceleration is. As per equivalence principle.

The answer depends on your frame of reference, i.e. an observer. In the first scenario, as we consider an orbit around the Sun, yes it will get tighter. In the second scenario, wherever you put an observer, the Earth will be free falling toward it (plus the initial velocity.) There is no absolute frame of reference to give an absolute answer.

Thank you. I know about chirality - in the Standard Model, in chemistry, in biochemistry (e.g. DNA), in biology, too. Most examples in biology I know of have explanations, e.g. chirality of snails. Those are not applicable to corals. Looking for new ideas ...

Yes, the actual calculation should be done from the Friedman equations. The result is the same - a uniform infinite mass density causes deceleration. It is one of the components. The total result - positive, negative, or zero - depends on other components, specifically, on the current rate of expansion and on cosmological constant (or, dark energy, if you prefer.)

The acceleration is relative to an observer. If an observer is attached to the mass, it does not accelerate anywhere. To any other observer, it accelerates - free falls - toward them with G*M/(R^2), where R is the distance from the observer and M is the mass of the stuff inside a ball of radius R.

With all due respect, we are going circles for some time already. The answers to all these objections are in the Susskind lecture 1, I've linked earlier. The math is simple and the result is calculable. The outcome is that the uniform infinite distribution of mass causes it to shrink. All points toward all points. If it started with expansion, this distribution causes the expansion to decelerate.