The Moon’s Giant-Collision Theory Proven Incorrect
techzwn.com
techzwn.com
Ack! This is not what "falsifiable" means.
Falsifiability is the property that states, there exists some hypothetical evidence which would be accepted as conclusive disproof of the theory. For instance, newton's third law ("equal and opposite") can be falsified by the discovery of a method of applying force which avoids any opposite application.
Extrapolating some, we can see that for all falsifiable theories, there is an extensive class of evidence which doesn't quite prove the theory wrong, but does weigh against the theory. Non-falsifiable theories don't have this property - for any method of assigning a probability of correctness to a non-falsifiable theory, there is a positive number below which that probability cannot go.
The reason the giant-collision theory should not be said to be "proven" incorrect is that it has not been. Its probability of correctness is still non-zero (and significant). However, it's not true that scientific theories cannot be "proven" incorrect - classical mechanics has been, for instance.
[Of course, a scientific theory could be disproven by being based on incorrect mathematical reasoning - but that's presumably not very interesting]
If that's the case I don't see how there is any way of 'proving' that the isotopic signatures we are matching with those of the moon are 'native' and not already part of some Earth/Theia mix - in which case they'd match with a Moon that was already part of an Earth/Theia mix. Without knowing the composition of the earth 4.5 billion years ago, I'm not sure you can say otherwise?
In this particular experiment they showed the isotopic proportions matched between here and the Moon.
The isotopic homogeneity of this highly refractory element suggests that lunar material was derived from the proto-Earth mantle, an origin that could be explained by efficient impact ejection, by an exchange of material between the Earth’s magma ocean and the protolunar disk, or by fission from a rapidly rotating post-impact Earth.
And that's even assuming that the "mass" is more or less solid - if it were ejected from a violent impact it's more likely that it would be more of a cloud of debris, in which case things get even more complex. So many "bodies" are involved that it becomes more of a fluid dynamics problem than an orbital mechanics one. The individual particles in the cloud interact with each other gravitationally, deflecting each other from their "return-to-sender" orbit. Parts of the cloud would fall to earth, parts would escape to space, and parts would stay in orbit to become a ring system or (as is hypothesized) one or more moons.
The theorized situation isn't so much like skipping a stone across the earth as totally vaporizing a big chunk of both the earth and the planet that hit it, and a fairly small part of the resulting cloud (about half according to some models) of debris managing to end up in orbit and eventually collapsing into a single body (the moon).
Actually, now that I think about it, wouldn't the result of the collision cause most of Earths contribution to be on the surface of the moon? If it was otherwise, then Earth would have had an ring much like Saturn at one point which then collected into whole to become the moon. That couldn't be true since we would have easily seen evidence on the moon. This theory of mine would mean that almost any samples taken from the moon would would be originally from Earth.
I'm not sure what evidence we would expect to observe on the moon to indicate whether it accreted from a proto-ring or was captured intact - could you elaborate a little?