Methuselah: Can Something Really Be Older Than The Universe?
“The size and age of the cosmos are beyond ordinary human understanding. Lost somewhere between immensity and eternity is our tiny planetary home.”
— Carl Sagan
When it comes to talking about the Universe and its fascinating discoveries, astronomers need to exercise some degree of caution. After all, there are things we understand, and things we don’t. However, the media is not bound by such rules. If a scientific discovery can be contorted and twisted to create a much more engaging story, then why not?
That is what happened with Methuselah — the star older than the Universe.
Here are a few headlines to give you an idea:
However, there are always a few facts that are conveniently left out by the popular media — because who doesn’t love a cosmic mystery!
In this article, I will explain why this claim is false — although, I do not endorse ruling out any possibilities till we have evidence of the contrary.
Let’s start with what we know — the age of the Universe.
The age of the universe is 13.8 billion years — plus or minus 20 million years. To put it in more readable terms, the universe is somewhere between 13.78 to 13.82 billion years old.
The Methuselah Star has been measured to be nearly 14.3 billion years old — that is, it has been around almost half a billion years before, well, everything else came into existence. Surely, that makes no sense. However, it wasn’t just the tin foil hat parade and conspiracy theorists, even credible reports stated that the age of Methuselah was scientifically calculated to be greater than that of the Universe.
So, what are we missing here?
Methuselah (or HD 140283) is a Population II star, meaning it was formed very, very early in the universe, when most stars were predominantly burning hydrogen and helium. These type of stars are metal-poor, that is, with barely any elemental matter heavier than helium.
(For those unaware, heavier elements such as carbon, lithium, oxygen and iron were formed in the cores of massive stars in the later period of the universe. Even the iron atoms in your blood right now were birthed inside a star through fusion!)
Why does it matter that Methuselah is a Population II star, you ask?
The struggle with Population II stars
This matters because a Population ll Star does not easily fit within the Hertzsprung-Russell diagram (HR diagram) — a visual plot that relates the brightness or luminosity of stars to their surface temperatures.
Within the diagram, as we move from bottom to top there is an increase in brightness, and from right to left there is an increase in temperature. When a new star is observed, it tends to fall into a distinct region or branch on the diagram, close to previously observed similar stars.
However, the Methuselah was added to the diagram based on interpretation of data from theoretical models of stellar evolution. We looked at millions of other stars to infer how they would age and then used that data to classify Methuselah in the diagram.
This had to be done as it is incredibly challenging to accurately calculate the luminosity and surface temperature of a single star over 200 light-years away — especially one that is not part of the local cluster. If our readings aren’t precise enough, we cannot calculate a well-constrained value for its age.
Based on our calculations, Methuselah would lie to the extreme right on the branch highlighted by the red box in the Hertzsprung-Russell diagram -
To reiterate, the star in question wasn’t classified like other stars; based on the actual values of their temperature and luminosity. The result saw it being placed in a region with no prior readings.
Naturally, even the calculated age of this star was unprecedented.
Why We Haven’t Discovered More Stars Like Methuselah
The reason is that most stars belonging to Population II and Population III (even older stars that are hypothesized to exist) are no longer visible to us — which is why Methuselah sticks out like a sore thumb. We are unsure of its characteristics because it has no previous specimens, a benefit that we get while classifying other stars in the HR diagram.
It is presumed to have formed a few hundred million years after the Big Bang, making it one of the oldest stars that we have ever known. It is highly likely that it will be one of the few Population II stars we will ever discover. And till we observe any other similar star, we will never truly be able to say how old Methuselah is .
Newer stellar models have suggested a revised age between 12 to 13.7 billion years. This fits perfectly with the framework of the Big Bang Theory—the beginning of the Universe.
However, this is not half as engaging, interesting or bizarre as claiming to have found a star older then the Universe — and the media needs their dose of high-octane breaking news!
Methuselah, named after the biblical patriarch with the longest lifespan in the Bible, is NOT older than the Universe itself. That is no different than claiming to be older than your parents.
The fact is that we are uncertain of its age by ± 0.8 billion years, which puts it over the threshold of 13.8 billion years. However, with improved observational tools (fingers crossed for James Webb!) we will be able to reduce that uncertainty drastically — and prove to those spreading misinformation that nothing can be older than the Universe.