The scale of emerging-market purchases is small so far in comparison with the 15 appetites of central banks in the richworld. Bank Indonesia, which already owns about 15% of tradable government bonds, may end up adding significantly to itsholdings. The National Bank of Poland could end up owning bonds worth about 8.7% of GDP, according to UBS, a bank, if itbuys all of the additional 16 required to finance the country’s stimulus plan. But no other central bank is 17 tobuy bonds worth more than 5% of GDP, UBS calculates. By comparison, the Federal Reserve already held Treasuries equivalentto about 10% of GDP at the start of 2020, and is expected to roughly double that percentage over the course of the year.Critics nonetheless worry that QE is both more dangerous and less necessary in emerging markets than it is elsewhere. Itimperils the hard-won 18 of monetary authorities that have struggled in the past to keep their distance from bigspending politicians. Brazil’s constitutional limits on the central bank, for example, reflect its history of hyperinflation, whengovernments 19 to the printing press to finance their populism. And although inflation is now firmly under control inmost big emerging markets (exceptions include Argentina, Nigeria and Turkey), many of these countries still worry that monetaryindiscipline can lead to destabilizing runs on their currency.Why then are central banks pressing ahead? They believe their bond purchases serve a distinct purpose. They are neither anunconventional way to lower borrowing costs nor an illicit one to finance the government. The aim instead is to stabilize financialmarkets. In Brazil the president of the central bank says its bond purchases will resemble foreign-exchange intervention. It willnot try to peg bond yields any more than it pegs the real. But it will try to smooth out 20 . The South African ReserveBank says that its purchases are not meant “to stimulate demand”, but to ensure a “smoothly functioning market”.(Adapted from the Economist, May 7th 2020 edition.)III. Reading Comprehension (15%)Gravitational-wave astronomers have for the first time detected a collision between two black holes of substantially differentmasses—opening up a new vista on astrophysics and on the physics of gravity. The event offers the first unmistakable evidencefrom these faint space-time ripples that at least one black hole was spinning before merging, giving astronomers rare insight intoa key property of these dark objects.“It’s an exceptional event,” said Maya Fishbach, an astrophysicist at the University of Chicago in Illinois. Similar mergerson which data have been published all took place between black holes with roughly equal masses, so this new one dramaticallyupsets that pattern, she says. The collision was detected last year, and was unveiled on 18 April by Fishbach and her collaboratorsat a virtual meeting of the American Physical Society, held entirely online because of the coronavirus pandemic.The Laser Interferometer Gravitational-Wave Observatory (LIGO)—a pair of twin detectors based in Hanford, Washington,and Livingston, Louisiana—and the Virgo observatory near Pisa, Italy, both detected the event, identified as GW190412, withhigh confidence on 12 April 2019. The LIGO–Virgo collaboration, which includes Fishbach, posted its findings on the arXivpreprint server.The latest event is unique. One of the two black holes that merged had an estimated mass of around 8 solar masses, and theother was more than 3 times larger, at 31 solar masses. This imbalance made the larger black hole distort the space around it, sothe other’s trajectory deviated from a perfect spiral. This could be seen in the resulting gravitational waves, which were createdas the objects spiralled into each other. All the other merger events that have been unveiled produced a wave that forms a similar‘chirp’ shape—which increases in both intensity and frequency up to the moment of collision. But GW190412 was different: itsintensity didn’t simply rise as in a chirp. “This makes this system very interesting, just looking at the morphology of the signal,”Fishbach said.Physicists had eagerly awaited such ‘non-vanilla’ events because they provide new, more precise ways of testing AlbertEinstein’s theory of gravity, the general theory of relativity. “We are in a new regime of testing general relativity,” saidMaximiliano Isi at the Massachusetts Institution of Technology in Cambridge, another LIGO member who was presenting at themeeting.In particular, researchers were able to use this data to discern the ‘spin’ of black holes. “We know with confidence that this
21. According to reading passage, Maya Fishbach says GW190412 is “an exceptional event” because __________.
(A) it’s the first collision between two black holes that detected in human’s history.
(B) more than one observatory detected the event and named collaboratively.[!--empirenews.page--]
(C) it is a collision of black holes with a strange mass discrepancy.
(D) it enables astrophysicist to know more about the Universe’s heavy chemical elements.