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Since Harland's sedimentary work and Budyko's models in the 1960s, geologists have hypothesized that the Earth may once have been completely frozen. There are various lines of evidence for this event.
What would it take to conclusively confirm or refute this hypothesis, short of going back in a time machine?
In order to confirm the snowball earth hypothesis, we'd need at least:
A paleogeographic model which extends to greater than 650ma and has been shown be be conclusively accurate throughout that entire period. (i.e. one we can trust)
Sedimentation structures/patterns (or other paleoclimate proxy data), consistent with a glaciation event, tied into the same time period, from the north pole to the south pole
Bennet et al showed that there are several origins of the 'dropstones' not associated to glacial deposits. The dropstones are the sole material, circunstantial, presented as evidence of global glaciations.
The whole story started because of the Faint Young Sun - only 70% of energy output leads to a frozen Earth - a Paradox because there was liquid water on Earth and Mars that required a Hot Past. The same with Mars Hot past (the CO2 feedback as a source of heat preservation was dismissed recently).
We have already strong biological and geological evidences, that can not be dismissed, against the Snowball Earth old theory:
Molecular phylogeny - Life’s evolution is strongly dependent in ambient thermal evolution as recorded by Life itself and demonstrated in:
Geological records have the same trend of high temperature in the past (∂18O(Knauth & Epstein, 1976) or of ∂30Si (Robert & Chaussidon, 2006) indicate a sea temperature above 65 ºC, eventually close to 90 ºC, earlier than 2 Ga. Several other studies confirm the results.
The Life, ie all cells - can only use monoatomic N(itrogen) that is not freely available on Earth. The atmospheric molecular N2 require huge pression and temperatures to be dissociated in N+N as used in the Haber-Bosch process invented in the start of XX century (ammonia to fertilize the soil and feed the humanity - growing exponentially since the 30s). Until then Life had to feed on itself (a shitty recycle) and the total bioma could not grow.
The conclusion can only be: The Snowball Earth Theory is dead.
But ... to solve the conundrum we have to put the planets closer to the Sun in the past or increment it's energy output. A new theory?
A paradigm shift was motivated by the following considerations:
Two studies were concluded outside the academia (not peer reviewed - blame the system and not the author):
Edit add:
Some (a lot of) people have prejudice against new ideas that appear out of the academia. In this case the new ideas grew in front of my eyes decades ago and if you find any error or anything to be better explained in those docs you can ask me. Be polite and do not pretend to judge them without reading the content as it seems to be the usual case. The first doc has more than 1000 downloads and not a single error was mentioned until now. Be the first to argue.
Quoting 'ressurected proteins' doc:
Our results are further supported by a nearly identical cooling trend for the ancient ocean as inferred from the deposition of oxygen isotopes. The convergence of results from natural and physical sciences suggest that ancient life has continually adapted to changes in environmental temperatures throughout its evolutionary history.
Fig 3 from the 'ressurected proteins' doc with the past temperature on Earth as recorded by Life that is incompatible with SBE
(proto-feathers - Ramphorhyncus longicaudus at Teylers Museum – Haarlem)
Edit Add:
Due to the fact that basic logic is absent in the comments ( ‘Atoms are not shrinking. I assume the rest of this answer is equally silly’) I’ll have to extend the implications of the Considerands above expressed to show that the downvotes are due to the lack of appropriated knowledge of laws of Logic and/or Physics. Playing with Legos or scaled trains/cars, designing Computer Models of the reality or engineering scaled material models (similitude) can give a better insight of the solution here briefly described.
The 2nd consideration “We measure...” was intended to show explicitly that the units of measure are in one to one correspondence with the atom properties with the example of atomic mass. It is obvious, by definition, that the same is true irt the charge unit. The length unit can be assumed to be in a one to one correspondence to the atomic Bohr radius. Assuming the constancy of the light speed ‘c’ the Time T is tied to the Length unit. The simple and intuitive mode of reasoning is this one ‘without atoms we have no units of measure at all then it follows that the units are in correspondence with the atom, whatever its actual ‘size’’. From this I see a logical error in the statement “Atoms are not shrinking” because no law of physics have stated that and I’m sure that it is not missing such law.
To hold the validity of physical laws requires to hold the invariance of non-dimensional combination of quantities and constants (e.g., $\pi$ theorem); this implies that the relationship between correspondent base units has to be the same. Thus, the units Mass M, Charge Q, Length L, Time T had to evolve at the same pace, lets say
$$\frac{[M_0]}{[M_1]}=\frac{[M_0]}{[M_1]}=\frac{[Q_0]}{[Q_1]}=\frac{[T_0]}{[T_1]}= \alpha(t)$$ and $\alpha$ function is the atomic scaling function.
The velocity is invariant $\frac{L\alpha}{T\alpha}$
The energy scale function is $\alpha$; being
$E_0 = M\ L^2\ T^{-2} \\
E_1= M\alpha\ L^2 \alpha^2\ T^{-2}\ \alpha^{-2}=E_0\alpha $
The acceleration and gravitational field $L\ T^{-2}$ scale as $\alpha^{-1}$
Lets see some examples:
The electron mass $m_e$ is left as a free parameter in Quantum Mechanics and in Atomic Physics but the ratios of the masses of particles have to be the same.
The 3th consideration: “The redshift of the radiation we receive from the past can be interpreted as the emission from larger atoms” was scrutinized at PSE and showed the impossibility to distinguish the spectrum of the atomic radiation emited from an atom in motion and the one of a scaled atom - PSE as acknowledged by the author of the accepted answer, after clarification that Wolfram equation on the hyperfine structure he used was indeed wrong.
Lets see that the Force is invariant under that transformation:
Newton 2nd law $F=mass\ \cdot\ acceleration$ (in SI units $kg*m/s^2$) and in dimensional analysis
$F_1=\frac{M\cdot\ L}{T^2}=\frac{M\cdot\ \alpha\cdot\ L\cdot\ \alpha}{(T\cdot\ \alpha)^2}=F_0\cdot 1$
The force of gravitation (Newton) has the same value $F_g=G\cdot\frac{M^2}{L^2}=G\cdot\frac{(M\ \alpha)^2}{(L\ \alpha)^2}$ and the same is valid to the electomagnetic Coulomb force.
The parameters $G,\varepsilon_0,c$ are invariant and the same irt the dimensionless constants.
From the list of the dimensionless quantities
we can pick any of these and check what happens, f.i.:
The Eötvös or Bond number ( related to the shape of bubbles or drops)
$E_0=B_0=\frac{\delta\rho\ g\ L^2}{\sigma}$
where $\rho, g, L, \sigma $ are density, gravitational acceleration, characteristic length and surface tension and in SI units $E_0\ units=[E_0] = \frac{kg/m^3\cdot m/s^2\cdot m^2}{kg*m/s^2/m}$ and inserting the scaling value we get for the system 1 the same value [E_0]
$[E_1]=[E_0]\cdot scaling(\alpha)=\frac{kg/m^3\cdot m/s^2\cdot m^2}{kg\cdot\ m/s^2/m}\ \cdot \frac{\alpha/\alpha^3\cdot \alpha/\alpha^2\cdot \alpha^2}{\alpha\cdot\alpha/\alpha^2/\alpha} \\
=[E_0]\cdot \frac{\alpha^{1}\ \alpha^{-3} \cdot \alpha^{1}\ \alpha^{-2} \cdot \alpha^2}{\alpha^{1}\cdot\alpha^{1}\ \cdot \alpha^{-2} \alpha^{1}} \\
=[E_0]\cdot \alpha^{1-3+1-2+2-1-1+2-1} \\
=[E_0]\cdot \alpha^{0}=[E_0]$
The 1st consideration is a basic tenet of physics that never should have been forgotten and was indeed in the minds of all the physicists a century ago. The difficulty of finding the correct explanation of the measured space expansion, besides the naif one: ‘the galaxies are moving away’ brougth philosophical problems and magical entities like the ‘dark’ energy, BB, inflation period, etc… in what in the universe is forbiden: ‘free lunches’.
This new model is not a theory but a model because it was drawn from data with no ‘IFs’ and no hidden or undeclared, unverified, postulates like the one ‘the atoms are not shrinking’. Because in the laboratory there is no feasible experiment to make evident that the atoms evolve, or not, one can not jump to a conclusion without the theoretical analysis like the one done in this model.
The actual function that describes the scaling of the matter was deduced to be $$\alpha(t_S)=e^{-H_0\cdot t_S}$$ and $t_S$ is the time unit of the system $S$ used as reference, a non evolving one.
In the meantime I’m traveling the desert receiving up and downvotes from individuals that did not studied this issue and have no other way to answer the million dollar question, except ‘I assume/believe’:
Is it the case that the space expands or the atoms that are shrinking?
Now we have enough data and knowledge to say that the Snowball Earth theory is dead because it was proved wrong by the Life itself and by the geological records.
A final remark - I commented that the temperatures on the graph are lower than the real ones because a rise in the temperature makes the seawater to migrate to the atmosphere and the pressure and the boiling point rises too. The studys only considered a standard atmsphere of 1 bar.
