A faint cosmic hum could solve the Universe’s expansion mystery

For decades, astronomers have known that the universe is expanding. To determine how fast it is growing today, scientists calculate a value called the Hubble constant. Multiple independent techniques are used to measure it, and because they rely on the same underlying physics, they should produce matching results. Instead, measurements based on observations of the early universe conflict with those drawn from the more recent universe. This mismatch is known as the Hubble tension, a...