By Charles Q. Choi
Analyzing ripples in the fabric of space and time created by pairs of dead stars may soon solve a cosmic mystery surrounding how quickly the universe is expanding — if scientists are lucky.
That’s the verdict of a new study, which may also shed light on the ultimate fate of the universe, the researchers who worked on it have said.
The cosmos has continued expanding since its birth about 13.8 billion years ago. By measuring the present rate of the universe’s expansion, known as the Hubble constant, scientists can deduce the age of the cosmos and details of its current state. They can even use the number to try to learn the fate of the universe, such as whether it will expand forever, collapse upon itself or rip apart completely.
Scientists use two primary methods to measure the Hubble constant. One involves monitoring nearby objects whose properties scientists understand well, such as stellar explosions known as supernovas and pulsating stars known as Cepheid variables, in order to estimate their distances and then deduce the expansion rate of the universe. The other focuses on the cosmic microwave background, the leftover radiation from the Big Bang, and examines how it has changed over time to calculate how quickly the cosmos has expanded.
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