Match the following :
Column I
(a) Cepheid Theory
(b) Electromagnetic Theory
(c) Nebular Theory
(d) Binary Theory
Column II
(i) Laplace
(ii) Dr. Banerji
(iii) Alfven
(iv) Lyttleton

Question

UnlockIAS · Accepted Answer

Correct — option (1). Column I holds four hypotheses about the origin of the solar system and Column II holds four names; the columns are printed alongside each other, but that is layout and asserts no pairing, so each theory has to be attached to its author from what is known of it. Take the one that is certain first. The Nebular Theory at (c) is Laplace's: Pierre-Simon Laplace set it out in 1796, proposing that a hot, rotating gaseous nebula contracted as it cooled, spun faster, and shed successive rings of matter at its equator which condensed into the planets while the residue formed the sun. So (c) goes with (i), and that single pairing decides the question, because option (1) is the only row that makes it. The other three pairings confirm the row rather than establish it. The Cepheid Theory at (a) is the work of A. C. Banerji, printed here as Dr. Banerji, who proposed in the early 1940s that the sun was originally a Cepheid, one of the class of pulsating stars, and that the approach of another star intensified its pulsation until matter was thrown off and condensed into the planets; so (a) goes with (ii). The Electromagnetic Theory at (b) is Hannes Alfven's, which brought the sun's magnetic field into the account and had ionised gas from a surrounding cloud sorted by that field according to the mass of its atoms before the planets formed; so (b) goes with (iii). The Binary Theory at (d) is R. A. Lyttleton's, in which the sun once had a companion star and a third, intruding star tore the companion apart, the debris being left in orbit around the sun; so (d) goes with (iv). The completed pairing is (a)-(ii), (b)-(iii), (c)-(i), (d)-(iv), which is option (1).

Why the other options are wrong — (b) This row gives the Nebular Theory at (c) to Dr. Banerji, and that alone disposes of it. The nebular hypothesis is the oldest of the four and the best known: Kant proposed a version of it in 1755 and Laplace gave it its classic form in 1796, and it is the one theory in this list that every candidate is expected to be able to place. The row compounds the error by giving the Cepheid Theory to Alfven, whose contribution was electromagnetic, and the Electromagnetic Theory to Lyttleton, whose contribution was the binary star. Nothing in it survives. The point worth taking away is procedural: in a four-by-four match it is enough to hold one pairing with certainty, because a single confirmed pair usually eliminates three of the four rows without any need to test the remaining pairs.  (c) This row gives the Nebular Theory at (c) to Alfven, which is wrong for the same reason as the previous row — the nebular hypothesis belongs to Laplace, whose 1796 account of a cooling, contracting and rotating nebula shedding rings is the version taught everywhere. Alfven's place in this list is the Electromagnetic Theory, which is a genuinely different idea: it makes the sun's magnetic field the agent that separates and arranges the ionised material out of which the planets form, and it belongs to the twentieth century rather than the eighteenth. The row also gives the Cepheid Theory to Lyttleton and the Binary Theory to Laplace, so it inverts almost every pairing in the question. A candidate who has fixed even the Laplace pairing will not reach it.  (d) This is the row most likely to catch a hurried reader, because it opens with a name everyone recognises: it gives the Cepheid Theory at (a) to Laplace, and Laplace is the one name in the second column that a candidate is sure to know. That familiarity is what the row trades on. Laplace belongs to the Nebular Theory at (c), and this row gives that to Dr. Banerji instead, while handing the Electromagnetic Theory to Lyttleton and the Binary Theory to Alfven. Every pair is wrong. The discipline that defeats it is to decide where your one secure name belongs before reading any row, and then to accept only a row that puts it there; reading the rows first lets a familiar name in the wrong slot pass for a familiar name in the right one.

Concept: Theories of the origin of the solar system divide into two families, and holding the division is worth more than memorising any single theory. The monistic or evolutionary family derives both the sun and the planets from a single parent body: Kant's and Laplace's nebular hypothesis is the classic case, and the modern solar nebula model, in which a rotating disc of gas and dust around the young sun accretes into planetesimals and then planets, is its descendant. The dualistic or catastrophic family requires a second body, usually a passing or companion star, to pull material out of the sun or out of its companion: Chamberlin and Moulton's planetesimal hypothesis, the tidal hypothesis of Jeans and Jeffreys, the binary star hypothesis of Russell and Lyttleton, the supernova hypothesis of Hoyle and Lyttleton, and Banerji's Cepheid hypothesis all belong here. Alfven's electromagnetic hypothesis stands somewhat apart, since its distinctive claim concerns the mechanism of sorting rather than the source of the material: the sun's magnetic field acts on ionised gas, and atoms of different mass are captured at different distances. The catastrophic theories fell out of favour largely because a close stellar encounter is far too rare an event to account for the number of planetary systems now known, and because material torn from a star would be too hot to condense; the nebular idea, in its modern form, is what survives.

State PCS 2022 Q4 — Geography PYQ with Answer

State PCS 2022 Q4 — Geography PYQ with Answer