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Thoughts regarding moon formation, dinosaur extinction hypotheses, ‘string theory’ (quantum physics), multiverse (cosmology): opinion


A recent news item online commemorates the anniversary of the launch of The Conversation, the online discussion forum written by academics from universities around the world. This writer has read the article ‘How the moon formed’ by Dr Christian Schroeder published on The Conversation on March 10 2020.

Leading supposition (or hypothesis) regarding formation of the Moon 

Schroeder’s article states that ‘how the Earth got its moon is a long-debated question’. To summarise, Schroeder states that ‘the front runner among the explanations is that ‘the Moon [was] formed [by] the collision between the early Earth and a rock called Theia’ (‘giant impact theory’).

Theia was estimated to be roughly half the Earth’s size and the collision was supposed to have occurred 4.5 billion years (4500 million years) ago. The impact of the collision was so great that parts of the Earth mixed with parts of Theia were ejected into Space and this eventually formed the Moon.

From other sources the writer has read this collision – the first major and probably the most ‘impactful’ collision in over 4.5 billion years of the Earth’s geological history – occurred a ‘mere’ 70 million years after the formation of the Earth from the debris of the solar system.

Dr Schroeder’s article cited recent evidence reported in the journal Nature Geoscience which may further buttress the Theia hypothesis. Coincidentally, while editing the draft of this article another contemporaneous article which provides further evidence of the Theia ‘proposal’ was published in the journal Science, on 29 March 2021: ‘A remnant of a protoplanet may be hiding inside Earth’ by Nicoletta Lanese.

Stronger hypothesis regarding the major cause of extinction of the Dinosaurs and other species?

There was yet another collision which occurred more than 4400 million years (plus or minus several dozen million years) after the presumed Theia collision. This latter-day or geologically more ‘recent’ collision was first proposed by Luis and Walter Alvarez, Frank Asaro and Helen V. Michel in their June 1980 article ‘Extraterrestrial Cause for the Cretaceous-Tertiary Extinction’ published in Science.

In so few words the article stated that a giant meteorite or ‘asteroid’ (more recent studies stated that it was probably a comet; according to the late Stephen Jay Gould in his book The Structure of Evolutionary Theory published in 2002 it was a ‘bolide’) that hit the Earth in what is now the Yucatan peninsular near the Gulf of Mexico led to the extinction of the dinosaurs and about 70 per cent of the then species on Earth.

The bolide that hit the Earth was supposedly six miles across. The size of that bolide or comet was a tiny fraction of what is called the Theia gigantic ‘rock’ or protoplanet which was postulated by some scientists to be roughly the size of the planet Mars that hit the newly-formed Earth around 4500 million years ago.

Around 4500 million years ago dinosaurs, not to say humans or homo sapiens – a handful of humans now postulate about the causes of the extinction of the dinosaurs (see below) – were far, far (far) (even in terms of geological time) in the ‘misty future’ (ie if the Theia hypothesis which has been proposed by some scientists is correct).

Now, this curiosity or ‘wondering’ arises in this dilettante writer’s mind. (The writer has learned his ‘science’, so to speak, from, in the complimentary sense of the phrase, popularisers of science like the late Stephen Jay Gould, the late Carl Sagan, the late Ernst Mayr, the late Martin Gardner, and to a lesser extent Richard Dawkins, to all of which I express my gratitude and from whose writings I have learned a lot).

Can the theory, postulate or supposition (not ‘stipulation’ though) that the asteroid/comet/bolide collision which occurred 65 to 66 million years ago be classified as a scientific hypothesis? If so is it a firm scientific hypothesis? The writer recalls that when it was first proposed in 1980 (and for perhaps more than a dozen years or so thereafter) there were quite a few ‘doubting Thomases’ so to speak of the (shall we say to give credit to the two main authors of the 1980 article) the Alvarezs’ initial proposal. From this writer’s perusal of the secondary literature perhaps a significant majority of the scientists (almost approaching consensus?) who have considered and investigated the matter are now of the view that the the main though arguably not the sole cause of the Cretaceous-Tertiary extinction was the comet collision that occurred around 66 million years ago.

Which is a stronger hypothesis: ‘Theia collision’, or comet or bolide collision?

Going back deep into the past of around 4500 million years, is the ‘Theia’ proposal regarding the formation of the Moon an arguable scientific hypothesis or not?

What are the views among geologists, earth scientists, astronomers and other scientists regarding the Theia ‘conjecture’, so to speak? Are there other serious alternative conjectures or theories regarding the origin of the Moon? Is there more (or less) agreement among concerned scientists towards a consensus regarding the formation of the Moon around 4500 million years ago compared to the cause of the Cretaceous-Tertiary extinction around 66 million years ago? Are both of these conjectures classifiable as valid scientific hypotheses? If so, which is the firmer hypotheses?

The above theories can be considered under the genre of ‘historical sciences’ whose nature and truth of the propositions cannot be proven by repeated experiments like in some of the physical sciences.


From two possible hypotheses regarding what can be termed as historical sciences a ‘quantum leap’ to a postulate, proposal or supposition in the non-historical science of quantum mechanics.

String theory in quantum mechanics: supposition or hypothesis?

In his partly if not largely iconoclastic tract (a sort of ‘intellectual biography’) Einstein’s Mistakes [:] The Human Failings of Genius (W.W.Norton & Co., 2008) the author Hans C. Ohanian describes string theorists of making:

the cute proposal that the ultimate subatomic entities – at the bottom of downward progression from atoms to electrons to nuclei, to protons and neutrons, to quarks and gluons – are not pointlike articles but tiny bits of string vibrating in a spacetime of 10 dimensions. For a great many years, a great many theorists labored over this string model with obsessive zeal, hoping that from the equations governing the dynamics of the strings they would be able to deduce and explain the properties of quarks and gluons and all the elementary particles and forces.                                            

(Pages 334-35)

It is clear from what Ohanian wrote that he wouldn’t condescend to call the string theory first proposed by three physicists in the 1970s as a scientific hypothesis, though he did use the phrase ‘cute [in not so complimentary sense of the word] proposal’.

This writer has quoted physicist Hans C. Ohanian’s dismissal or almost debunking of the shall we say suppositions of the string theorists. Paraphrasing the saying ‘one swallow does not make a summer’, one physicist’s debunking of other physicists’ concepts of string theories may not necessarily be conclusive that the string theories are no more than ‘cute proposal(s)’.

However, the more pertinent query or the writer’s ‘wondering’ is, in a comparative context, and across scientific disciplines, which theory by acclamation (through consensus or majority scientific opinion) is the firmer or firmest (scientific) hypothesis?

If none of them arguably are unequivocally firm scientific hypotheses can they be described as ‘suppositions’? Among the three theories considered so far, the Theia supposition, the cause of the Dinosaur extinction supposition or the string theories, which is the firmest or weakest?

This writer’s (un)scientific opinion is that the Cretaceous-Tertiary extinction theory is the firmest among the three (of course subject to refutation with evidence and arguments).

‘Multiverse’ ‘supposition’ in ‘other’ cosmologies?

In the above brief statement regarding the ‘Big Bang’ the word THIS Universe is written in emphasis. ‘The Big Bang’ scientific hypothesis (or is it now a cosmological fact?) is that to be somewhat tautological the ‘Big Bang’ that occurred 13800 million years ago is how our universe started. This is virtually the consensual views of most cosmologists perhaps since the 1950s.

‘On the other hand’ or as regards the ‘other’ cosmological theory the online ‘defines’ multiverse as:

hypothetical collection of potentially diverse observable universes, each of which would comprise everything that is experimentally accessible by a connected community of observers (emphases added)

And the online definition states that multiverse is ‘a theoretical reality that includes a possibly infinite number of parallel universes’ (emphasis added).

The writer should add that he uses the word (scientific) hypothesis above in a somewhat different sense than the definition. Perhaps the word ‘assumption of potentially diverse … universes’ may do as well to define in so few words the meaning of ‘multiverse’.

The online Britannica article, from this writer’s discernment, provides no conclusive statement to indicate (or is it to vindicate?) that the multiverse cosmology (?) is a (firm) scientific hypothesis.

To query or indeed question the Miriam Webster definition scientifically (albeit not pedantically or lexically) can ‘reality’ be ‘theoretical’? Is it equally felicitous or infelicitous to describe ‘theoretical reality’ as ‘postulated’ or ‘posited reality’ or as a ‘postulation’ (and again not ‘stipulation’)?

Assuming but not conceding, stipulating or supposing that ‘multiverse’ exist(s), are the cosmological or physical laws in those multiverse(s) the same as THIS Universe? Are or would there be in those multiverse ‘Big Bangs’ galaxies, stars, planets, dark matter or not? Is the speed of light the same in those multiverses? Or does what we call the phenomena of light both in its wave or corpuscular dimensions exist or not in those ‘dimensions’ (pun intended) in the multiverse?

Perhaps a search on Google may or may not indicate (non-scientific) ‘answers’ or suppositions to these queries but this writer has refrained from ‘Googling’ for ‘answers’ to these queries.

In the light of the uncertainties or (non)answers to these queries the writer has above (in)advisedly used the term ‘other cosmologies’, for if multiverse(s) exist then all of them or each of them may (or may not) have their own ‘other’ cosmologies different from THIS Universe cosmology.

In popular science books this writer has read in the past few weeks Einstein’s Mistakes and Stephen Hawking’s The Theory of Everything [:] The Origin and Fate of the Universe (emphasis added; Hawking did use the singular) no mention far less discussion is made of the multiverse concept.

The first edition of Theory of Everything was published in 1996. From what this writer recalls Stephen Hawking’s A Brief History of Time (first edition 1988) also does not mention the multiverse idea.

The writer has read Stephen Hawking’s and Leonard Mlodinow’s The Grand Design (first published 2010) but off-hand does not recall whether the co-authors endorse or espouse the multiverse concept or not. Notwithstanding the prestige of these two renown scientists, their endorsement or for that matter refutation of a (scientific) idea is not necessarily conclusive or indicative of a physical or cosmological reality.

Albert Einstein (14 March 1879 – 18 April 1955) died before the ‘multiverse’ idea come fully into the cosmological picture so to speak. It could be added that when Einstein published his landmark Theories of Special Relativity and General Relativity in the years 1905 and 1915 respectively, the prevailing cosmological theory was the ‘Steady state’ theory: a universe (but not necessarily multiverse) without beginning or end.

But since the late 1920s the ‘Big Bang’ theory posits a ‘beginning’ to this universe (so to speak and writing retrospectively without supposing there are other ‘universes’).

Perhaps it is not wrong to state the Big Bang postulate or hypothesis has, if not replaced, then largely taken over from ‘Steady state’ as the prevailing cosmological posit. Now, with the intrusion (as a manner of expressing) of the multiverse concept can a different version of ‘Steady state’ be envisaged, since in the multiverse there would be no ‘beginning’?

One more book by a physicist with the word ‘multiverse’ in the title can be mentioned. The late physicist Victor Stenger (29 January 1935 – 25 August 2014) (perhaps) posthumously published book is titled God and the Multiverse: Humanity’s Expanding View of the Cosmos (Prometheus, 2nd printing edition 2014). In the Preface Victor Stenger wrote that “[o]f course the existence of other Universes has not been empirically established at least not yet” albeit he immediately added that “the verification of the multiverse is not beyond the realm of possibility” (page 19).

As stated above physicist Hans C. Ohanian’s dismissal of string theory is not necessarily conclusive as to whether the theory is valid or not. Likewise, the late Victor Stenger’s admission that the multiverse concept (as of 2014 when the book was published and perhaps one could add in early 2021) is not ‘empirically verified yet’, albeit it is ‘within the realm of possibility’ is not indicative – far less conclusive – that the multiverse concept is a firm scientific hypothesis.

Imagining the historical events in Earth’s geological history and the postulates of string theory and multiverse cosmologies

An excerpt from the song by the late John Lennon goes: ‘Imagine there is no heaven’. For perhaps a minority of persons it may not take much of an imagination to envisage ‘no heaven’, but for hundreds of millions of others it is much easier and comforting to imagine that ‘there is heaven’.

As a person interested in general science and philosophical issues pertaining to science it is easier for this writer to ‘imagine’ the Theia and the ‘Dinosaur and other species extinction’ (shall I now say?) scientific hypotheses with varying degrees of verifiability than the arcane string theory of quantum mechanics (or modern physics) and multiverse as an (other) cosmological concept.

Neither imagination nor empirical verification (depending on its modes and methods as well as the content and contours of the subject being empirically investigated) is always necessarily a sufficient condition (though perhaps they are necessary ones) to verify the subject’s existence or reality.

From this writer’s perusal of the topics and mainly using his imagination, readings and reason the historical sciences of the Moon formation and the main cause of dinosaur and other species extinction is more convincing than the string theories and multiverse cosmologies.

This article is dedicated to the memory of my late mother Dr Myint Myint Khin, (15 December 1923 – 19 June 2014) a retired Professor of Medicine who established the ‘Myint Myint Khin Scientific Literacy Award’ for Burmese authors who write on science matters.

Dr Myint Zan is a retired Professor of Law. He established the Myint Zan Fellowship in Philosophy at ANU for early career researchers for the years 2018 to 2021 and an undergraduate Myint Zan prize in the Philosophy of Science.

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