The Star of Methuselah does not disprove the Big Bang

The vast majority of astronomers accept the Big Bang – the theory that the universe began about 13.8 billion years ago in a fiery cataclysm. However, this idea is not accepted by everyone. Some Big Bang skeptics claim that the universe is about 6,000 years old, while others claim that the universe is eternal. Although they disagree with each other, both agree that the Big Bang theory is wrong, and one observation they point to is the existence of estimated stars whose age is older than the universe itself. If such a star existed, it would be the death knell of the Big Bang.

“star of methuselah”

Dubbed the “star of Methuselah,” HD 140283 is certainly old and is generally accepted as one of the oldest known stars. A paper published in 2013 estimated its age at 14.45 billion years, with an uncertainty of ±0.8 billion years. This is older than our most accurate estimate of the age of the universe, 13.797 ± 0.023 billion years.

While the Methuselah star is not unique (in the sense that there are other stars that are similarly ancient), it is the oldest star for which the quoted uncertainty is relatively low, and thus is regarded by those individuals who do not believe the Big Bang as providing the strongest argument against the theory.

A star is born

Astronomers believe that HD 140283 is old because the star has a very low “metallicity”. Metallicity, to astronomers, is a measure of the percentage of a star’s chemical composition that is composed of elements other than hydrogen and helium.

When the universe began, the universe consisted almost entirely of hydrogen (75%) and helium (25%), with a tiny trace of heavier elements (~0.01%). (These percentages reflect mass content; when simply counting atoms, hydrogen was 92% and helium 8%.) This was also the initial formation of the first stars, which formed perhaps as early as 100 million years after the Big Bang. These stars, which astronomers call third stars, were much heavier and brighter than the Sun, and in their cores, stellar fusion cooked up the first kinds of heavy elements. Cluster III stars lived only a few million years before exploding in supernovae, which blasted their heavier elements across the universe.

Heavy elements mixed with hydrogen and helium gas, forming cluster II stars, and the process repeated again, with these subsequent supernovae adding heavier elements to the universe. The result was an I-number of stars with a relatively high composition of heavy elements. Our sun is the inhabitant of I-star.

However, the star of Methuselah is the star of Population II: a cosmic relic from the birth of the universe. They contain much less oxygen and iron than, for example, our sun. Astronomers use a combination of measured star brightness, observed percentages of non-hydrogen and non-helium elements, and sophisticated models of stellar evolution to determine the star’s age. And as mentioned earlier, in 2013, astronomers estimated an age greater than the age of the universe. So, is this a real problem? Is HD 140283 the death knell for the Big Bang?

Uncertainty matters

No. For example, other calculations of the star’s age indicate that he is much younger. One estimate in 2015 puts the age at 13.7 ± 0.7 billion years, while an estimate in 2021 puts the age at an earlier age of 12 ± 0.5 billion years. The fact that different scholars estimate such a range of ages means that the discrepancy is much ado about nothing.

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And even if the seemingly problematic 2013 estimates are 100% reliable, we need to be careful. Importantly, we must not only compare the dot estimate for the star’s age with that of the Universe (that is, 14.45 versus 13.797 billion years), but we must also take into account the uncertainties. The uncertainty in estimating the age of the Methuselah star is ±0.8 billion years, which means that the actual age of the star is between 13.65 and 15.25 billion years. (Technically speaking, there is a 70% chance that the actual age of the star is within this range, and a 30% chance that it is outside the range. This also means that there is a 15% chance that the actual age of HD 140283 is less than 13.65 billion years. )

While the 2013 estimate for the age of the Methuselah star suggests that it may be older than the universe, the fact that this estimate is also Consistent with the star being smaller than the universe, the scientific community doesn’t see it as a problem. It is only an issue among those who want to disprove the Big Bang Theory.

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