NASA report: What we think we know about the universe is very wrong

For decades, scientists have been grappling with what is considered to be the most fundamental question about the cosmos: How fast is our universe expanding?

The rate of expansion influences everything from how galaxies form to how they might one day drift apart.

Determining the expansion rate of the universe, a number called the “Hubble constant,” shapes our entire understanding of the cosmos, its age, and its ultimate fate.

“Hubble tension” expansion conundrum

Unfortunately, though many brilliant minds have dedicated their lives to finding the answer to this riddle, all who have tried thus far have failed, running repeatedly into a brick wall that has come to be known as the “Hubble tension.”

Adam Riess, a physicist at Johns Hopkins University in Baltimore, has been at the forefront of this debate. “With measurement errors negated, what remains is the real and exciting possibility that we have misunderstood the universe,” Riess admitted.

Riess, who won a Nobel Prize for discovering that the universe’s expansion is accelerating due to dark energy, has been working tirelessly to resolve what’s known as the Hubble Tension.

Why the Hubble constant matters

But before diving deeper, let’s consider why the expansion rate — called the Hubble constant — is so crucial.

Named after Edwin Hubble, who first observed that galaxies are moving away from us, this constant helps us map out the history and future of everything we see in the night sky.

Determining it with precision has been a major goal of astronomers for decades.

When the Hubble Space Telescope was launched in 1990, one of its main objectives was to pin down the universe’s expansion rate.

Before Hubble, estimates of the universe’s age ranged wildly from 10 to 20 billion years — a huge uncertainty.

Thanks to Hubble’s observations of Cepheid variable stars — stars that pulsate at regular intervals and serve as cosmic mileposts — we now have a more precise age of about 13.8 billion years.

Webb telescope to the rescue?

Some scientists wondered if the discrepancies in measurements were due to errors in Hubble’s data. Maybe, they thought, the way Hubble measured distances had some hidden flaws.

Then came the James Webb Space Telescope (Webb), launched to great fanfare as the successor to Hubble. Webb’s infrared observations of Cepheids matched Hubble’s optical data perfectly.

“Combining Webb and Hubble gives us the best of both worlds. We find that the Hubble measurements remain reliable as we climb farther along the cosmic distance ladder,” Riess explained.

Hubble vs. Webb vs. expansion

Despite the new data, the tension between measurements remains. The Hubble and Webb telescopes confirm one universe expansion rate, based on observations of the local universe.

Meanwhile, observations from the early universe, like those from the Planck satellite’s mapping of the cosmic microwave background radiation, suggest another.

This leaves cosmologists scratching their heads. Is there something about the fabric of space we don’t yet understand? Does resolving this discrepancy require new physics, or is there another explanation?

Brenda Frye tackles Hubble and expansion

In October 2024, as reported by NASA, Brenda Frye from the University of Arizona and an international team took a different approach.

They used gravitationally lensed supernovae to measure the Hubble constant — a method independent of previous techniques.

While observing a densely populated cluster of galaxies, they noticed something unusual. “What are those three dots that weren’t there before? Could that be a supernova?” the team wondered.

It turned out to be a Type Ia supernova, an explosion of a white dwarf star, magnified and split into multiple images by the gravitational lensing effect of the intervening galaxy cluster.

What is gravitational lensing?

Gravitational lensing is important to this experiment. The lens, consisting of a cluster of galaxies situated between the supernova and us, bends the supernova’s light into multiple images.

This effect not only magnifies the supernova but also allows scientists to measure the time delays between the images, providing another way to calculate the Hubble constant.

Their analyses confirmed that these dots corresponded to an exploding star with rare qualities.

The team’s work provided a Hubble constant value of 75.4 kilometers per second per megaparsec, plus 8.1 or minus 5.5. For context, one megaparsec is about 3.26 million light-years.

“Our team’s results are impactful: The Hubble constant value matches other measurements in the local universe, and is somewhat in tension with values obtained when the universe was young,” Frye concluded.

Another strikeout… add Brenda Frye to the long list of brilliant minds still probing the universe for an answer to Hubble tension.

This is getting sad, now what?

So, where does this leave us?

The Hubble Tension isn’t going away. It might be telling us that there’s new physics waiting to be discovered.

Perhaps our understanding of dark energy, dark matter, or other fundamental forces needs to be revised.

“We need to find out if we are missing something on how to connect the beginning of the universe and the present day,” Riess pointed out.

It’s possible that new theories or modifications to existing ones could bridge the gap.

Shaking things up with new theories

Could the solution lie in something entirely unexpected? Perhaps there’s a new particle or force that affects the expansion rate. Or maybe the nature of dark energy changes over time.

Some theories even propose the existence of extra dimensions or modifications to gravity at large scales. It’s also worth considering that the universe might not be uniform in all directions.

If there are variations in the density of matter and energy across vast distances, this could affect expansion rates in ways we haven’t fully accounted for.

Maybe everyone is completely off base and dark matter doesn’t even exist? Or maybe we’re looking in the wrong place — what if the answers can be found by looking for dark matter in rocks on Earth?

One thing’s for sure: the cosmos isn’t giving up its secrets easily. But that’s part of the thrill of science. Every answer leads to new questions.

Hubble constant, Hubble tension, mysterious universe

In the end, the universe is reminding us that there’s still so much we don’t know. The quest to figure out how fast our universe is expanding has led to some fascinating discoveries and even more intriguing questions.

Scientists like Adam Riess and Brenda Frye have used powerful tools like the Hubble and James Webb Space Telescopes to measure the Hubble constant with increasing precision.

Their efforts confirm that the local universe is expanding at a certain rate, but this doesn’t quite line up with measurements from the early universe.

This mismatch, known as the Hubble Tension, suggests there might be something we’re missing in our understanding of the cosmos. Maybe there are new physics to uncover, or perhaps our current models need some tweaking.

What’s clear is that the universe isn’t giving up its secrets easily, and that keeps things exciting for astronomers and physicists alike.

As we look ahead, upcoming missions like NASA’s Nancy Grace Roman Space Telescope and ESA’s Euclid mission offer hope for new insights. Until then, we can marvel at the fact that we’re part of an ever-expanding universe that’s still full of surprises.

The full study was published in the Astrophysical Journal Letters.

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