"Was the Earth formed as an accretion disc?"

[Robittybob1]

After 15 years of following a chain of thought I was surprised to read in a post the other day an idea which seemed to gel with the concept of Earth formation that I had independently developed.

 

 

MigL, on 16 Apr 2015 - 05:19 AM, said:

You cannot just eliminate Earth's angular momentum by snapping your fingers. If you could dissipate it and 'brake' the Earth, it would take time, and in the end, you'd find that the Earth would be close, if not spherical.
Just like, as it was coming together 4.5 Bi yrs ago, it was probably extremely flattened ( accretion disc ), and slowly rotating. It then speeded up ( conservation of ang. momentum ) and reached an equilibrium of forces in the somewhat flattened spherical shape it has today. The very fact that the surface of the Earth sits appreciably higher in the gravity well, at the equator, is because it feels less net force. In effect, it weighs less. Even rock feels the effects of buoyancy, given several billion years to react, and so the surface has 'floated' up higher at the equator than the poles.

 

I had contemplated that the Earth and Theia had formed at opposite sides of this torus of matter that orbited the protosun at the approximate radius of the Earth's current orbit. In my concept there were fewer planets than the hundreds of planets sometimes proposed, but within the torus there would be many (thousands) planetesimals. They would be formed but they do not need to jump from torus to torus for they are gravitationally bound within their own region.

 

I think of it like a ring that is broken into two places and not necessarily evenly but these long strips of matter are condensed into asteroid sized chunks and they accrete at opposite ends of the orbit.

 

As the main mass (Proto-Earth) gathers in the smaller bits on the path in the orbital direction the asteroid sized pieces and dust/gases are slowed in their orbit, dropping them to a lower orbit but because they have become gravitationally bound ahead and from behind they strike the accretion disc on the inner side.

 

The opposite effect is found with the material accreting from the trailing side, it being accelerated by the gravitational forces will attain a higher orbit but it doesn't slow down so it strikes the growing Earth on the outer side (away from the Proto-sun). The whole mass of stuff being gravitationally pulled together keeps the accretion disc rotating at a speed where the outer parts are nearly at orbital speed.

 

Now I have thought this through many times but have been very hesitant to write it down and present it, for I thought one would just get a runaway rotation of the whole mass, but with the concept of Theia being an unstable planet forming at the L3 Lagrangian point and later going into a "Horseshoe Orbit" with the Earth and at the same time itself forming, there is the possibility of the two outer parts of their accretion discs clashing. The matter will hit each other conserving momentum in multiple inelastic impacts by slowing. This would result in the matter heating up and falling into the gravitational centers.

 

I can see there is a huge potential for mixing of the material (clashing accretion discs) to become isotopically similar for these reasons, without the need for a giant impact.

 

The reason I have been encouraged to present the outline of my Earth formation model was because I can now see it was not too difficult to control the incoming material through having it rotating in an accretion disc at near orbital speed.

 

The features that can be discussed are:

1. The planets form in the late protosun period where there is not as much Solar Wind and radiant pressure to blow away gasses needed to hold the asteroid chucks gravitationally together.

 

2. Because the whole mass is rotating with outer parts at orbital speed there is a high rate of loss of volatile matter (Hydrogen Helium Methane Water CO2 etc).

 

3. There is sufficient mass of liquids surrounding the two planets to allow for Moon Capture.

 

4. The high rate of liquid/gas loss results in the Earth losing sufficient mass so the Moon begins drifting away even before the tidal acceleration can take effect. (Until the oceans became shallow enough there is minimal tidal acceleration. That is why the current rate of tidal acceleration has not been present throughout the history of the Moon.)

 

The idea was rather odd to begin with but over the years new evidence has tended to support rather than refute such a scenario.

 

What do you reckon?

Edited April 20, 2015 by Robittybob1

[pavelcherepan]

I have said it already in a PM but will repeat again.

 

I don't think this idea is valid. The 'extremely flattened' and 'slowly rotating' accretion disk can apply to the entire Solar System when it was forming, but doesn't seem to be applicable to the formation of planets.

 

First of all, it seems highly unlikely to have a 'torus' of material at the exact current orbital distance of the Earth. What could cause such torus to form? What would cause 8 separate tori to form? Or was formation of the Earth different from all other planets?

 

How does this idea explain highly elliptical orbits of near-Earth asteroids and the fact that orbits of a lot of bodies in SS are highly tilted to the plane of ecliptic?

 

If it was a rotating accretion disk that obviously implies some sort of center of mass, why wasn't this disk perturbed by gravitational influence of the Sun and other forming planets? This 'asteroid chunks' you're talking about - were they all exactly equal size, evenly distributed and moving with the same exact angular velocity in the orbit? If they weren't equal size and evenly distributed, their orbits would change over time due to interaction with each other? On the other hand, if they were evenly distributed how come they started accreting to form Earth?

 

Your whole idea of how 'some pieces will hit the disk from outside and some will hit it from the inside' is based on exactly what?

 

The reason I have been encouraged to present the outline of my Earth formation model

<...>

The features that can be discussed are:

 

Sorry, but you don't get to choose what features can be discussed. I, for example, want half a dozen questions answered that I've formulated above. And no, you didn't present a model, just a collection of random guesses, unsupported by any kind of evidence same as what we've seen in your other threads about formation of Theia and Earth.

 

But coming to your discussion points:

 

1.

 

2. Are you implying that centrifugal force is responsible for the loss of hydrogen, helium and other volatiles?

 

3. Moon capture hypothesis has been more or less disproved by now. The mass ratio Moon/Earth is the biggest of all planet/satellite systems in SS and it's highly unlikely that Earth could've captured the Moon. Also isotopic composition doesn't support it.

 

4. Tidal effect doesn't have to be related to oceans. The Earth's crust and Moon crust experience tidal effects as well.

 

 

What do you reckon?

 

Same things I've told you in all your other threads pertaining to formation of Earth/Theia - your ideas are based exactly on zero evidence and can't explain observed phenomena.

Edited April 20, 2015 by pavelcherepan

[Robittybob1]

I have said it already in a PM but will repeat again.

 

I don't think this idea is valid. The 'extremely flattened' and 'slowly rotating' accretion disk can apply to the entire Solar System when it was forming, but doesn't seem to be applicable to the formation of planets.

 

First of all, it seems highly unlikely to have a 'torus' of material at the exact current orbital distance of the Earth. What could cause such torus to form? What would cause 8 separate tori to form? Or was formation of the Earth different from all other planets?

 

How does this idea explain highly elliptical orbits of near-Earth asteroids and the fact that orbits of a lot of bodies in SS are highly tilted to the plane of ecliptic?

 

If it was a rotating accretion disk that obviously implies some sort of center of mass, why wasn't this disk perturbed by gravitational influence of the Sun and other forming planets? This 'asteroid chunks' you're talking about - were they all exactly equal size, evenly distributed and moving with the same exact angular velocity in the orbit? If they weren't equal size and evenly distributed, their orbits would change over time due to interaction with each other? On the other hand, if they were evenly distributed how come they started accreting to form Earth?

 

Your whole idea of how 'some pieces will hit the disk from outside and some will hit it from the inside' is based on exactly what?

 

 

Sorry, but you don't get to choose what features can be discussed. I, for example, want half a dozen questions answered that I've formulated above. And no, you didn't present a model, just a collection of random guesses, unsupported by any kind of evidence same as what we've seen in your other threads about formation of Theia and Earth.

 

But coming to your discussion points:

 

1.

 

2. Are you implying that centrifugal force is responsible for the loss of hydrogen, helium and other volatiles?

 

3. Moon capture hypothesis has been more or less disproved by now. The mass ratio Moon/Earth is the biggest of all planet/satellite systems in SS and it's highly unlikely that Earth could've captured the Moon. Also isotopic composition doesn't support it.

 

4. Tidal effect doesn't have to be related to oceans. The Earth's crust and Moon crust experience tidal effects as well.

 

 

Same things I've told you in all your other threads pertaining to formation of Earth/Theia - your ideas are based exactly on zero evidence and can't explain observed phenomena.

I'll reply to each part of your rebuttal but not all tonight.

 

I don't think this idea is valid. The 'extremely flattened' and 'slowly rotating' accretion disk can apply to the entire Solar System when it was forming, but doesn't seem to be applicable to the formation of planets.

By the time the solar System had the accretion disc there was a massive core in the center, so the whole thing isn't flat.

The proto-Earth would be surrounded by the accretion disc, but I am imagining that MigL thought the accretion disc is the point of impact for the incoming matter not so much the proto-Earth taking the impact as is so often depicted in the media on Earth formation.

 

3. Moon capture hypothesis has been more or less disproved by now. The mass ratio Moon/Earth is the biggest of all planet/satellite systems in SS and it's highly unlikely that Earth could've captured the Moon. Also isotopic composition doesn't support it.

I'm surprised for I've not seen any of this proof. Two things in my theory help the Earth capture the Moon were the co-orbital origin and the vastness of the Early Earth's volatile atmosphere and oceans.

[swansont]

Two things in my theory help the Earth capture the Moon were the co-orbital origin and the vastness of the Early Earth's volatile atmosphere and oceans.

 

!

Moderator Note

Let's stay on point here. The topic of discussion is Earth formation.

[pavelcherepan]

By the time the solar System had the accretion disc there was a massive core in the center, so the whole thing isn't flat.

The proto-Earth would be surrounded by the accretion disc, but I am imagining that MigL thought the accretion disc is the point of impact for the incoming matter not so much the proto-Earth taking the impact as is so often depicted in the media on Earth formation.

 

It seems to me a bit strange to think of an accretion disk as something solid or so dense that it can be impacted on. How dense do you think it was?

[MigL]

All planets have some degree of rotation ( I mean spin, not orbit ).

I find it hard to believe that this rotation is a result of impacts.

More likely, it is simply conservation of angular momentum; as planets coalesced and collapsed they speeded up their rotation.

Which means their original constituent material was slowly spinning about an axis.

In effect, an accretion disc

[StringJunky]

All planets have some degree of rotation ( I mean spin, not orbit ).

I find it hard to believe that this rotation is a result of impacts.

More likely, it is simply conservation of angular momentum; as planets coalesced and collapsed they speeded up their rotation.

Which means their original constituent material was slowly spinning about an axis.

In effect, an accretion disc

Yes, as the matter coalesces, like a skater pulling her arms in, its rate of rotation increases.

[Robittybob1]

 

It seems to me a bit strange to think of an accretion disk as something solid or so dense that it can be impacted on. How dense do you think it was?

If you go outside and see a falling star burning up in the atmosphere, the material is just burning up in a non-dense gas, yet the dust particles will finally hit the ground. Now imagine what happens when a meteorite slams into something like the rings around Saturn, is it going to get through? Now if we were to combine the two, a gaseous atmosphere and chunks held out in orbit due to their rotation, that is the density that it would present. It would not stay like that for long, as the initial planet building phase is relatively short period.

....

First of all, it seems highly unlikely to have a 'torus' of material at the exact current orbital distance of the Earth. What could cause such torus to form? What would cause 8 separate tori to form? Or was formation of the Earth different from all other planets?

Last year there was a photo taken of a planetary system forming and the rings (tori) were visible. The dimensions of the new planetary system were rather large compared to our Solar System (Sol) but what I have always proposed is that the inner planets have to form prior to the star going main sequence so the amount of volatile matter is maximized during the planetary build.

So seeing this is difficult, for the proto-star is not producing a lot of light at this stage, but it maybe visible in the infrared spectrum.

(I'll get a link to this star system soon.)

 

 

 

4. Tidal effect doesn't have to be related to oceans. The Earth's crust and Moon crust experience tidal effects as well.

 

Tidal acceleration of the Moon is a difficult nut to crack. At the current rate of drift, multiply that by the age of the Moon, and the Moon would have needed to start off on the other side of the Earth! So if the Moon was closer to the Earth in the past and the rotation was faster and the gravitational effects stronger why was the rate of migration slower.

Only reason I can put it down to is that the oceans were deeper so the tidal bulge kept up with the Moon's rotation and hence there was no effective torque.

How do you explain the historical slow rate of migration? Does the explanation tie in with the Earth formation?

Edited April 20, 2015 by Robittybob1

[Robittybob1]

Last year there was a photo taken of a planetary system forming and the rings (tori) were visible. The dimensions of the new planetary system were rather large compared to our Solar System (Sol) but what I have always proposed is that the inner planets have to form prior to the star going main sequence so the amount of volatile matter is maximized during the planetary build.

So seeing this is difficult, for the proto-star is not producing a lot of light at this stage, but it maybe visible in the infrared spectrum.

(I'll get a link to this star system soon.)

BBC News - Planet formation captured in photo

Planets in formation - does this picture confirm Robittybob's Hypothesis?

http://www.bbc.com/news/science-environment-29932609

If they reckon there are planets already formed there why didn't they point them out? It fits with what I understand happens too, but in my hypothesis there would be the formation of planetesimals within each band and then the whole band would with the action of gravity within the ring pull itself around to form a planet, but the planets would form within the inner ring first.

 

 

[pavelcherepan]

Yeah, I saw that one before, but what is different from your idea is that in this photo dark bands represent areas of the original protoplanetary disk that have been depleted of material and where proto-planets have already formed. Hence before the formation of those we'd be looking at a fairly uniform disk of some 2000 AU in diameter rather than tori you're talking about.

 

The reason why they haven't pointed them out is because planets are tiny compared to the entire disk and very dim so they are not clearly visible. The diameter of the entire disk is about 2000 AU = 300*10⁹ km, then a planet the size of Earth will be (2.1*10^-7)% of this diameter.

 

BTW, why are you talking of yourself in a third-person?

Edited April 21, 2015 by pavelcherepan

[Robittybob1]

Yeah, I saw that one before, but what is different from your idea is that in this photo dark bands represent areas of the original protoplanetary disk that have been depleted of material and where proto-planets have already formed. Hence before the formation of those we'd be looking at a fairly uniform disk of some 2000 AU in diameter rather than tori you're talking about.

 

The reason why they haven't pointed them out is because planets are tiny compared to the entire disk and very dim so they are not clearly visible. The diameter of the entire disk is about 2000 AU = 300*10⁹ km, then a planet the size of Earth will be (2.1*10^-7)% of this diameter.

 

BTW, why are you talking of yourself in a third-person?

It is an enormous star system. I am of the opinion the dark areas are thinned out areas of the protoplanetary disc but not because of a planet moving along these tracks, but because there is some reason of pressure waves radiating out from the proto-star.

I liken this to the formation of sand dunes or patterns in the sands on the beach. There would be regions of radiation pressure pushing material back from the star but behind that gravity will be bringing matter forward. But behind the first band the effect is repeated for a series of times (maybe 9 times as for the Solar System).

 

 

https://youtu.be/CfopeatOXgM?t=96

Edited April 21, 2015 by Robittybob1

[Mordred]

Take a look and Google density waves on the protoplasmic disk. ( if you study it in sufficient detail, different element/compound mixtures result in varying velocities due to the sum of forces and acceleration).

 

Key note f=ma now think in terms of a system wide force (system universal) upon particulates of varying mass.

( why do planets have different compositions).)(think sand and water)

Edited April 21, 2015 by Mordred

[Robittybob1]

Take a look and Google density waves on the protoplasmic disk. ( if you study it in sufficient detail, different element/compound mixtures result in varying velocities due to the sum of forces and acceleration).

 

Key note f=ma now think in terms of a system wide force (system universal) upon particulates of varying mass.

( why do planets have different compositions).)(think sand and water)

Do you mean the protoplanetary disk?

I see an article about the "gap formation in protoplanetary disks" thanks. The maths is too difficult for me to understand.

http://www2.astro.psu.edu/users/alex/astro497_8.pdf lays out the information in an easier to understand method.

One thing I'm wondering is what the idea of "disk self gravitation means" exactly, for I had always thought that gravity within the tori would be sufficient to drive accretion (so it is likely the diameter of the rings could still be contracting as gravitational accretion is occurring. (This becomes a necessity when you think of the size of the above mentioned star system, http://www.bbc.com/news/science-environment-29932609 asPavelcherapan says "The diameter of the entire disk is about 2000 AU = 300*109 km...."

Edited April 21, 2015 by Robittybob1

[Robittybob1]

I am noticing some differences between the current models and my proposal. Within each torus the average velocity of the matter is at orbital velocity so the chucks as they form are not slowed by the gas surrounding them but because of their shape have an inner gravitation. So any particle is gravitated to the center of the torus cross section. This way water is able to be in a liquid form within the torus which allows the grains to be sticky.

The ratio of gas to grains is also much higher than what I hear in the models being discussed. In my model the ratio would be up to 40 parts gas to 1 part rocky grain rather than the 100 parts of grains to 1 part gas as I heard being discussed in a lecture by Leonardo Testi.

Source of information:

Edited April 21, 2015 by Robittybob1

[pavelcherepan]

All planets have some degree of rotation ( I mean spin, not orbit ).

I find it hard to believe that this rotation is a result of impacts.

More likely, it is simply conservation of angular momentum; as planets coalesced and collapsed they speeded up their rotation.

Which means their original constituent material was slowly spinning about an axis.

In effect, an accretion disc

 

OK. I see your point and indeed it is valid, but still there are some inconsistencies. For starters, there is evidence to support that outer giant and ice giant planets have formed from such an accretion disk but they all share one feature that is not present in inner planets - all of those have large and developed systems with dozens of natural satellites and rings (however tiny those may be). Some of those satellites may have been captured asteroids and comets but all the larger satellites of giant planets are thought to have formed with the planet and from the same accretion disk.

 

What do inner planets have? Mars has two satellites, but they are captured asteroids, most likely; Earth has one, but the theory of formation of Earth/Moon from the same material is even less supported than the theory of Moon capture; Venus and Mercury both have no satellites.

 

Also, all giant planets are theorized to have a core composed of silicate rocks and ice, so even for those, the formation of rocky center of accretion precedes accretion of gas cloud. Current models mainly show that such rocky centers are created mostly by collisions of initial dust and rock particles.

 

And, finally, by the time rocky planets were forming the inner Solar System was already quite severely deprived of gases and volatiles so even if accretion disks were present in the formation of inner planets, these wouldn't be large and dense and majority of mass gain was from collisions between small rocky bodies on highly elliptical orbits,

[Robittybob1]

 

OK. I see your point and indeed it is valid, but still there are some inconsistencies. For starters, there is evidence to support that outer giant and ice giant planets have formed from such an accretion disk but they all share one feature that is not present in inner planets - all of those have large and developed systems with dozens of natural satellites and rings (however tiny those may be). Some of those satellites may have been captured asteroids and comets but all the larger satellites of giant planets are thought to have formed with the planet and from the same accretion disk.

 

What do inner planets have? Mars has two satellites, but they are captured asteroids, most likely; Earth has one, but the theory of formation of Earth/Moon from the same material is even less supported than the theory of Moon capture; Venus and Mercury both have no satellites.

 

Also, all giant planets are theorized to have a core composed of silicate rocks and ice, so even for those, the formation of rocky center of accretion precedes accretion of gas cloud. Current models mainly show that such rocky centers are created mostly by collisions of initial dust and rock particles.

 

And, finally, by the time rocky planets were forming the inner Solar System was already quite severely deprived of gases and volatiles so even if accretion disks were present in the formation of inner planets, these wouldn't be large and dense and majority of mass gain was from collisions between small rocky bodies on highly elliptical orbits,

Sorry to butt in but that was interesting that you think the satellites around the giant planets formed from the same accretion disc as did the planet. Certainly suggests an accretion disc of quite an enormous size if that was the case.

Venus may have had a moon in the past.

 

the formation of rocky center of accretion precedes accretion of gas cloud......

I don't think that is true. Can you see how it forms in my scenario, together. The gas is trapped in the torus and the whole torus forms the accretion disc and the planet (plus moons if you like). Except in the Earth's case I proposed the Moon forms from an L3 Lagrangian body.

 

by the time rocky planets were forming the inner Solar System was already quite severely deprived of gases and volatiles so even if accretion disks were present in the formation of inner planets, these wouldn't be large and dense and majority of mass gain was from collisions between small rocky bodies on highly elliptical orbits,....

That can be achieved in another way too, if the inner planets form in the late protosun period before the gas and volatiles are blown away.

[pavelcherepan]

 

 

Venus may have had a moon in the past.

 

Any evidence to support this?

 

 

 

I don't think that is true. Can you see how it forms in my scenario, together. The gas is trapped in the torus and the whole torus forms the accretion disc and the planet (plus moons if you like). Except in the Earth's case I proposed the Moon forms from an L3 Lagrangian body.

 

Torus... How can an entire torus form an accretion disk? You might need to clarify your 'torus idea', some drawings or pictures will help. Given the latest comment I can't figure out what it looks like.

 

And some information for you to check:

 

 

 

According to the solar nebular disk model, rocky planets form in the inner part of the protoplanetary disk, within the frost line, where the temperature is high enough to prevent condensation of water ice and other substances into grains.^[47] This results in coagulation of purely rocky grains and later in the formation of rocky planetesimals.^[c][47] Such conditions are thought to exist in the inner 3–4 AU part of the disk of a Sun-like star.^[1]

 

 

 

The formation of giant planets is an outstanding problem in the planetary sciences.^[15] In the framework of the solar nebular model two theories for their formation exist. The first one is the disk instability model, where giant planets form in the massive protoplanetary disks as a result of its gravitational fragmentation (see above).^[43] The second possibility is the core accretion model, which is also known as the nucleated instability model.^[15][50] The latter scenario is thought to be the most promising one, because it can explain the formation of the giant planets in relatively low-mass disks (less than 0.1 M_☉).^[50] In this model giant planet formation is divided into two stages: a) accretion of a core of approximately 10 M_⊕ and b) accretion of gas from the protoplanetary disk.^[1][15] Either method may also lead to the creation of brown dwarfs.^[51][52] Searches as of 2011 have found that core accretion is likely the dominant formation mechanism.

[Robittybob1]

 

Any evidence to support this?

 

 

Torus... How can an entire torus form an accretion disk? You might need to clarify your 'torus idea', some drawings or pictures will help. Given the latest comment I can't figure out what it looks like.

 

And some information for you to check:

 

 

If I was to hand draw a picture I can scan it to this computer, then what do I do?

Think of a torus as a rolled out dough strip but then curved into a ring but don't join the ends fully. Now imagine that dough having some sort of memory and contracting into a lump again by it pulling both ends back into the main body. I think of it like a very long worm that is able to contract its length into slug shaped mass.

I'll have to look at your references later.

"Does Venus Have Moons?

"http://www.universetoday.com/14250/does-venus-have-moons/

 

 

Venus and Mercury are the only planets that do not have moons. There are even a few asteroids that have moons. Venus; however, may not have always been moonless.

There are a few different theories floating around to explain why Venus does not have a moon. The first is based on a series of large impacts. Some scientists think that , like Earth, Venus was impacted by a large mass asteroid or planetesimal in the early part of the history of our Solar System. The first impact would have cast a large amount of ejecta into orbit around the planet. That ejecta would have coalesced into a moon over millenia. The second stage of the theory holds that another large impact caused the planet to go into retrograde spin. The new direction of the planet’s rotation destabilized the moon’s orbit, causing it to eventually impact the surface. A similar situation is in action on Mars’s moon Phobos as we speak. That moon will impact the Martian surface in about 25 million years. This theory may have been substantiated by a 2006 study done by Alex Alemi and David Stevenson at the California Institute of Technology.

A second hypothesis holds that Venus has had moons at several points in history. Each moon would have been of varying size, but all had one thing in common: they were stolen away by the Sun. This theory is also applied to Mercury. The theory proposes that the Solar gravity is too strong and strips each planet of any moons that may have been in orbit. The solar tides destabilize the orbits of the moons and they are slowly drawn into impact courses with our star.

It is all theoretical but needed in someway to explain Venus' retrograde spin.

 

Double Impact May Explain Why Venus Has No Moon

http://www.scientificamerican.com/article/double-impact-may-explain/

 

 

A new model suggests that our sister planet may have in fact had a moon, but that it was destroyed.

There is always a chance! I have just left it as a possibility.

Edited April 22, 2015 by Robittybob1

[Robittybob1]

When you make the torus from playdough for the Earth Moon set up you might have a smaller blob and a larger blob of dough, roll it out with tapered ends. Now lay the two rolls out into a circle with the centers of the pieces on opposite sides of the middle (I think there is no option but this will be the case).

Now within the cross section of each dough strip there will be self-gravity pulling radially inward and along the lengths, so they will shorten and become thinner (and hence more dense allowing condensation and crystallization), or there could even be nodes forming along their lengths (representing planetesimals) but all the nodes are linked gravitationally to the ones next to it (mainly via the enormous gaseous content).

The whole thing is orbiting the proto-sun so the arms which contract toward the proto-Earth node will either be slowed in orbit or sped up in orbit. This means the accretion disk is fed from the outside on one side and the inside on the other and this will keep the accretion disk spinning but it can only spin at a certain rate or else it will spread out further (depends on orbital speed for that distance), but as the mass of the core keeps on increasing the orbiting material will always be below orbital speed and hence falling toward the core (Proto-Earth or Proto-Theia).

The same thing will be happening on the opposite side of the Sun forming Theia.

 

That explanation feels correct physically, can you fault it?

Edited April 23, 2015 by Robittybob1

[Strange]

That explanation feels correct physically, can you fault it?

 

"Feels correct" is not science and not falsifiable. As there are no scientific models that match this, one can only assume that your "feelings" are leading you astray.

[Robittybob1]

 

"Feels correct" is not science and not falsifiable. As there are no scientific models that match this, one can only assume that your "feelings" are leading you astray.

If you have an idea, it is essential that you can imagine it happening? If it went against your gut feelings it would silly to promote the idea. Even in MigL's original quote, which that and other posts were the initiators of the thread, there was a lot of feelings. MigL felt it was unlikely that the Earth's rotation on formation was caused by random impacts but he liked the idea of an accretion disk.

If you think I'm going "astray" is that not just another feeling and in contrast, not a feeling of feeling right as in the case of MigL and myself, but one of negativity.

I admit the idea is original but it works physically. The physics is right, the rotations are right, and it uses the material as it is seen in the photographic images.

 

15 years ago I did an experiment to see how the dust could accumulate into planets, so I got a large circular basin and partly filled it with water laced with dust (flour) sprinkled into it, I stirred it, rotated it, and left it overnight to see what would happen.

To my surprise next morning the flour had formed annular concentric circular rings in the basin, with patterns of density next to areas of no flour. The idea was born that the protoplanetary dust disk could form into rings and then those rings would form into planets.

Edited April 23, 2015 by Robittybob1

[Bignose]

If it went against your gut feelings it would silly to promote the idea.

This is why science is all about specific testable predictions.

 

Here in an old article I remember being talked about when I was in school: http://www.colorado.edu/physics/EducationIssues/T&LPhys/PDFs/McDermott2b.pdf

 

Basically, it shows that a large percentage of students -- even ones who got very good marks -- have no real concept of what acceleration is. In other words, their 'gut feelings' are wrong or at least miscalibrated on something that is literally physics 101. It is not hard to extrapolate that gut feelings on things more complicated than that are even less reliable.

 

Again, science has fixed this by specific testable predictions, almost always generated from a math equation and compared to experimentally measured data. Gut feelings are great. The can be the kernel to a scientific idea. But gut feelings alone are not science, and you must also be exceptionally ready to accept that your guy feeling was wrong if the predictions don't agree with the measurements. As human beings, most of us struggle with that part of the process.

Edited April 23, 2015 by Bignose

[Robittybob1]

This is why science is all about specific testable predictions.

 

Here in an old article I remember being talked about when I was in school: http://www.colorado.edu/physics/EducationIssues/T&LPhys/PDFs/McDermott2b.pdf

 

Basically, it shows that a large percentage of students -- even ones who got very good marks -- have no real concept of what acceleration is. In other words, their 'gut feelings' are wrong or at least miscalibrated on something that is literally physics 101. It is not hard to extrapolate that gut feelings on things more complicated than that are even less reliable.

 

Again, science has fixed this by specific testable predictions, almost always generated from a math equation and compared to experimentally measured data. Gut feelings are great. The can be the kernel to a scientific idea. But gut feelings alone are not science, and you must also be exceptionally ready to accept that your guy feeling was wrong if the predictions don't agree with the measurements. As human beings, most of us struggle with that part of the process.

I have put the idea up for debate, because the physics and the gut feeling seem to suggest it is correct. I'm not basing it on gut feeling alone. In that study a reasonable number of students got the concept of acceleration right. I have been looking for 15 years for some idea that really shows a fundamental error to my planet forming process and it hasn't happened.

[Bignose]

I'm not basing it on gut feeling alone.

I must have missed that post where you presented a mathematical model, made from predictions from it, and compared it to known measurements...

 

Without that, it's all just story telling and 'gut'.

[Robittybob1]

I must have missed that post where you presented a mathematical model, made from predictions from it, and compared it to known measurements...

 

Without that, it's all just story telling and 'gut'.

They have been done on other sites but math has not been needed here as yet as far as this discussion has gone. I have previously looked at the total amount of material that could have used in making the two planets (sorry one planet, for it is only recently that I am more determined to show Theia as a co-orbital planet), and the effects of this mass on the core.

In this thread I am wanting a more general discussion at this stage regarding the process of the accretion disk. Can the accretion disk process be detailed mathematically, and are you sure you can say more with maths than you can with words?

Edited April 24, 2015 by Robittybob1