1. No magic or omnipotence
I am not going to discuss a point if a god (or anything omnipotent or magical or capable of breaking the laws of physics/nature) is going to be invoked either as a conclusion or a starting possibility in any discussion on the origin of life.
2. No argument of "always having existed". I will only have reasonable discussions on this topic if we can agree that there was a time in our universe where life as we know it, did not exist.
3. Abiogenesis as is currently formulated is impossible.
That is, no non-living mixture of any chemical ingredients in any environment, at any complexity can generate anything like life as we know it in terms of metabolism and reproduction.
If anyone reading this can accept all three of these premises (even if just for argument's sake) then I will happily engage in conversation. I can defend these axioms/premises to the hilt. If, when reading this, you believe these axioms to be contradictory, you are obviously not trying hard enough.
Friday, July 27, 2018
Thursday, July 19, 2018
PHILAE versus 67P don't forget the AM
Most analysis on why Philae "bounced" on the surface of 67P focus on the various failures of the legs, jet, screws and hooks which, if even one worked well, should have stuck the landing. My hypothesis that I am placing here, is that the landing was indeed stuck, but that the failure to consider the effect of de-spinning the fly-wheel inside Philae when considering the conservation of Angular Momentum (AM) was completely the reason it *jumped and spun*.
Philae would have managed to, with well designed legs and a stable rotation, screw at least one of the legs and be stationary enough, and signal such back to ROSETTA that the landing stuck. One of the first things that Philae then does, is to de-spin the fly wheel. However, with its long legs giving such leverage, the de-spin could have almost been designed to send it flying again.
Monday, July 02, 2018
My ideas for Haumea (Plutoid, TNO)
Haumea has been found to be elongated, with two moons, a ring, and not in hydrostatic equilibrium but rotating fast enough that centrifugal forces match mutual gravity near its extremities.
Knowledge about similar objects out at this distance (Pluto, Charon, Enceladus) have been used together with laws of angular momentum to work out what is physically possible. It ignores formation mechanisms at this point so as to concentrate on what is physically and mechanically possible given observations of Haumea and several other well observed analogues.
Pluto, Charon and Enceladus have been found to have ice shells and liquid water oceans beneath. Geysers on Enceladus go to form a ring at Saturn, so this probably explains the formation of Haumea's ring. Out-jetting of water at speed is what is happening at Enceladus, and this would be enough to torque even such a large body as Haumea. A thick ice shell would be enough to hold up to compression at the neck as the centrifugal force, friction, and conservation of Angular Momentum does the rest.
There will be gradual and even stretching of the neck as angular momentum is increased - in the same way as couples ice-skaters do the "spiral of death"
Tidal friction from the moons and ring keeps the motion circularised in the same way as the skating spin.
Knowledge about similar objects out at this distance (Pluto, Charon, Enceladus) have been used together with laws of angular momentum to work out what is physically possible. It ignores formation mechanisms at this point so as to concentrate on what is physically and mechanically possible given observations of Haumea and several other well observed analogues.
Pluto, Charon and Enceladus have been found to have ice shells and liquid water oceans beneath. Geysers on Enceladus go to form a ring at Saturn, so this probably explains the formation of Haumea's ring. Out-jetting of water at speed is what is happening at Enceladus, and this would be enough to torque even such a large body as Haumea. A thick ice shell would be enough to hold up to compression at the neck as the centrifugal force, friction, and conservation of Angular Momentum does the rest.
There will be gradual and even stretching of the neck as angular momentum is increased - in the same way as couples ice-skaters do the "spiral of death"
Tidal friction from the moons and ring keeps the motion circularised in the same way as the skating spin.
Sunday, July 01, 2018
Conditions for Contact Binary via collision
This post is to demonstrate that the conditions for CB via collision require highly balanced rotational and translational components in two similarly sized objects for them to retain their individuality as lobes in an otherwise combined object. This to demonstrate both that binary asteroids can not be a source for contact binary asteroids, and that random primordial collisions cannot be either.
1: Formerly connected bodies "reconfiguring"
As shown in a previous blog post, with the real case of couples skaters to demonstrate, bodies twist away from each other to retain angular momentum using their previous independent rotation as a dynamo (at the point of collision in the case of asteroidal bodies)
2: Independently rotating objects colliding from outside each other's hill spheres at "baby crawling" speed.
Inelastic collisions are of course possible for non-rotating (or trivially rotating bodies that collide in the perfect offset to cancel independent rotation). This is because the required collisional/deformation damping is obtained passively and gives a reaction force in the correct direction opposite to motion, and proportionally to motion so that the force stops when the relative velocity between bodies comes to zero.
A head on collision with a random (in observed ranges of possibilities) rotation or offset collision even with no initial rotation makes an inelastic collision impossibly rare given:
Coherent bodies - Mainly solid that can deform but not to the point of liquidity.
The two bodies are of similar size - smaller body is no less than about a third the radius, or no less than a tenth of the moment of inertia in rough figures.
Due to the laws of physics, forces that perform torque on each other must balance.
Overall angular momentum must be conserved.
If work is required to perform torque to change rotation that must be in the amount and direction made possible by friction, reaction force or gravity.
The following is a way to create model to test generated samples to verify this blog's order of magnitude analysis:
http://www.euclideanspace.com/physics/dynamics/collision/threed/index.htm
For a perfectly inelastic collision to ensue, not only relative speeds must be damped to zero, but relative rotation rates must also be damped to zero and still be touching. At the point of touching, the combined bodies' moment of inertia is at the minimum - Therefore, the rotational velocity required to maintain angular momentum is at its maximum. The kinetic energy associated with the required rotation is also at a maximum. There is work required to achieve this synchronised higher rotation unless the initial conditions are perfectly selected. The same fluidity that allows damping of the impact force allows shear perpendicular with the relative spin velocities which would throw the bodies apart further than reactive forces alone could do. In other words, a notionally inelastic collision would convert rotational velocity to inertial frame velocity in all except perfectly tuned cases which are extremely rare given the assumption of random initial spin state.
Friction under tensile stress or associated with outward movement (Stretch) is the only option to passively glue the bodies together keeping coherent orientation. With stretch (or expanding orbit) there is natural damping as the moment of inertia increases for the duo in proportion to its reduced velocity. Whether loosely connected at the neck or two bodies orbiting the barycentre, outward movement from previously connected bodies is the only passive way to stabilise mutual spin.
Pairs skaters use this particular rule of thumb to spectacular effect with the "spiral of death" spin. The technique spirals the (female) skater outwards with her head balanced inches above the ice. The gradual outward release damped with the action of muscles gives exceptional control that appears paradoxical and adds to the appearance of magic levitation of the head off the ice.
1: Formerly connected bodies "reconfiguring"
As shown in a previous blog post, with the real case of couples skaters to demonstrate, bodies twist away from each other to retain angular momentum using their previous independent rotation as a dynamo (at the point of collision in the case of asteroidal bodies)
2: Independently rotating objects colliding from outside each other's hill spheres at "baby crawling" speed.
Inelastic collisions are of course possible for non-rotating (or trivially rotating bodies that collide in the perfect offset to cancel independent rotation). This is because the required collisional/deformation damping is obtained passively and gives a reaction force in the correct direction opposite to motion, and proportionally to motion so that the force stops when the relative velocity between bodies comes to zero.
A head on collision with a random (in observed ranges of possibilities) rotation or offset collision even with no initial rotation makes an inelastic collision impossibly rare given:
Coherent bodies - Mainly solid that can deform but not to the point of liquidity.
The two bodies are of similar size - smaller body is no less than about a third the radius, or no less than a tenth of the moment of inertia in rough figures.
Due to the laws of physics, forces that perform torque on each other must balance.
Overall angular momentum must be conserved.
If work is required to perform torque to change rotation that must be in the amount and direction made possible by friction, reaction force or gravity.
The following is a way to create model to test generated samples to verify this blog's order of magnitude analysis:
http://www.euclideanspace.com/physics/dynamics/collision/threed/index.htm
For a perfectly inelastic collision to ensue, not only relative speeds must be damped to zero, but relative rotation rates must also be damped to zero and still be touching. At the point of touching, the combined bodies' moment of inertia is at the minimum - Therefore, the rotational velocity required to maintain angular momentum is at its maximum. The kinetic energy associated with the required rotation is also at a maximum. There is work required to achieve this synchronised higher rotation unless the initial conditions are perfectly selected. The same fluidity that allows damping of the impact force allows shear perpendicular with the relative spin velocities which would throw the bodies apart further than reactive forces alone could do. In other words, a notionally inelastic collision would convert rotational velocity to inertial frame velocity in all except perfectly tuned cases which are extremely rare given the assumption of random initial spin state.
Friction under tensile stress or associated with outward movement (Stretch) is the only option to passively glue the bodies together keeping coherent orientation. With stretch (or expanding orbit) there is natural damping as the moment of inertia increases for the duo in proportion to its reduced velocity. Whether loosely connected at the neck or two bodies orbiting the barycentre, outward movement from previously connected bodies is the only passive way to stabilise mutual spin.
Pairs skaters use this particular rule of thumb to spectacular effect with the "spiral of death" spin. The technique spirals the (female) skater outwards with her head balanced inches above the ice. The gradual outward release damped with the action of muscles gives exceptional control that appears paradoxical and adds to the appearance of magic levitation of the head off the ice.
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