New research suggests our Universe may be significantly younger than previously calculated. If the findings of this study are correct, it could change what we know about the Cosmos.
The age of the Universe, staring with the big bang, is generally thought to be around 13.8 billion years old. However, a new study from the Max Planck Institute for Astrophysics (MPA) suggests the Universe may be significantly younger than believed — around 11 billion years old.
The Hubble constant — a measure of the rate at which the Cosmos is expanding — is the critical figure in determining the age of the Universe. The faster galaxies are flying apart from each other, the younger the Universe must be to have expanded its present size.
“There are multiple ways to measure distances in the Universe, based on our knowledge of the object whose distance is being measured. A well-known technique is the luminosity distance using supernovae explosions,” explains Sherry Suyu of the MPA, an expert on using gravitational lensing to measure the Hubble constant.
The Bends? I Thought that was from Scuba Diving…
Gravity, much like glass lenses, can bend light around large objects like galaxies, focusing it like a telescope. This effect, not surprisingly, is called gravitational lensing. A pair of gravitational lenses, denoted B1608+656 and RXJ1131, were utilized to examine light from distant quasars (highly energetic galaxies with extremely active supermassive black holes near their centers).
This effect has recently become increasingly common as a means to measure distances to far-flung galaxies. When an image is split passing through a gravitational lens, photons heading along a curved path take more time to circumvent the massive object than light that took a more direct path. By measuring this time difference, astronomers are able to determine the angular diameter distance (a comparison of the visible size of the object at the size of the “lens”).
The galaxies which created the gravitational lenses are located, roughly, 2.6 million and four million light years from Earth. Both B1608+656 and RXJ1131 showed multiple images of quasars sitting behind them, as seen from Earth.
Data from these observations was examined, revealing a simple relationship between the brightness of the object and its distance from Earth. This formula (expected to be accurate to within 12 and 20 percent) was applied to data from 740 known supernovae.
The value they calculated for the Hubble constant is significantly higher than most other estimates, calculated through different methods. While most measurements of the Hubble constant place the figure around 74 kilometers per second per megaparsec (km/sec/Mpc). This means that for every ~3.25 million light years the object is from Earth, its apparent velocity from us increases by about 74 kilometers per second. There is nothing special about our place in the Universe — an identical effect would be witnessed by observers from any vantage point.
Other recent studies have found other variations in the currently-accepted value of around 74 km/sec/Mpc. In July 2019, images of red giant stars taken with the Hubble Space Telescope suggested a value for the Hubble constant of around 70 km/sec/Mpc,
This new study suggests a Hubble Constant (H0) between 74 and 90 km/sec/Mpc. A value at the upper end of that range would suggest the Universe is expanding much faster than we thought, implying the Universe would be significantly younger than we currently understand.
“Different methods of measuring H0 produce results that disagree with each other, which could be a sign of new physics or of systematic errors in the methods,” researchers report in Science.
Why are you Running Away?
Before the 1920’s, people did not know of any galaxies beyond the Milky Way. Astronomer Edwin Hubble was the first to recognize that certain objects were families of stars in their own right. He also discovered a linear relationship between the distance to the galaxy and how fast it seems to be receding from us.
“Based on this observation, Hubble concluded that the universe expands uniformly. Several scientists had also posed this theory based on Einstein’s General Relativity, but Hubble’s data, published in 1929, helped convince the scientific community,” NASA explains.
Nearing the dawn of the 21st century. NASA recognized Hubble by naming their revolutionary new space telescope in his honor. Launched in 1990, this instrument revealed that not only is the Universe expanding, but it has been expanding at an ever-increasing rate since about eight billion years after the big bang. The force driving this acceleration is called dark energy, and understanding the nature of it is one of the great mysteries in astronomy.
“I would feel infinitely more comfortable in your presence if you would agree to treat gravity as a law, rather than one of a number of suggested options.”
― Neil Gaiman, The Kindly Ones
The limited sample size of just two gravitational lenses and the uncertainty inherent in the formula obtained in this study create significant uncertainty in the higher value suggested for the Hubble constant. Several objects, including some stars, galaxies, and planets, are measured to be more than 11 billion years old. This discrepancy suggests a new series of hurdles for any value of the Hubble constant significantly above the currently accepted figure.
However, if supported by new observations, the findings presented in this study could hold significant implications for our current understanding of the Cosmos.
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