Cosmic Microwave Background Tells Story of the Universe — Dare to Know

The Cosmic Microwave Background yielded new information to researchers. Find out why this helps us to better understand the origin and fate of our Universe.

I’ve had a few favourite sitcoms over the years. As a small boy, I enjoyed the gentle humour of the Dick Van Dyke Show.

Later on, my favourite sitcom by far was MASH. I’d probably say that it still has that distinction. I’ve seen every episode and practically have them all memorized. Even so, if it pops up in my video feed, I’ll drop everything and watch it again.

Most recently, I enjoyed the Big Bang Theory. Combining science, modern relationships and general goofiness, I came to think of all the characters as people I knew and enjoyed spending time with.

“Fourteen Billion Years Ago, Expansion Started. Wait!”

I’m thinking about that program today because of its theme song. The iconic Canadian band Barenaked Ladies composed and performed it. The opening line is, “Our whole Universe was in a hot dense state, then nearly 14 billion years ago expansion started. Wait!”

Cornell University released some good news for both the TV show and the band this week. They’ve published the most accurate measurement of the age of the Universe ever made. It confirms that our Universe is just under 14 billion years old, so there’s no need to edit the ever-present theme song.

After analyzing all of the data, and doing some large-scale geometry, the figure the research team came to was 13.77 billion years. The margin of error on this estimate is a very narrow 40 million years.

Research Team Landed On 13.77 billion Years

This isn’t exactly earth-shaking news, but it’s very reassuring. It’s right in line with the expert consensus that the Big Bang took place roughly 13.8 billion years ago. This solidifies what cosmologists already knew.

The research team conducted the study using data from the Atacama Cosmology Telescope Array in Chile. They sifted through the data to track slight variations in the Cosmic Microwave Background (CMB).

We’ve discussed the CMB a few times in these pages. Back in 1964, when Robert Wilson and Arno Penzias were setting up the Holmdale Horn Antenna for Bell Labs in New Jersey, they detected a faint but steady signal in the background.

A remnant of the Light Flaring Forth from the Big Bang

No matter where they pointed the antenna, the signal was there. After ruling out all of the other possibilities, they came to realize that what they were receiving was the remnant of the light flaring forth from the Big Bang.

That remnant is what we now call the Cosmic Microwave Background. It’s unequivocal evidence of how our Universe’s beginning. Their accidental discovery netted Wilson and Penzias the Nobel Prize.

This ancient light was in the visible range when the Big Bang generated it. Still, on Earth today, we find it shifted into the microwave spectrum. It’s remarkably similar in all directions, but there are subtle differences, and scientists can make discoveries by studying the slight variations.

“Confidence in Measurements of Universe’s Oldest Light”

The result from the Cornell research team matches Cosmic Microwave Background estimates by a separate team using the Planck Satellite. As lead author Steve Choi put it, “This gives us more confidence in measurements of the universe’s oldest light.”

The astrophysicists from Cornell also weighed in on a more controversial topic. We’ve devoted a few stories here to the discrepancy in scientists’ efforts to pin down the exact rate at which the Universe is expanding.

Cosmologists call that rate the Hubble Constant, and they’ve been measuring it in different ways. The discrepancy isn’t wildly inconsistent-we know that the figure is in the neighbourhood of 70 kilometres per second per megaparsec (km/s/Mpc).

The Figure is in the Neighbourhood of 70 km/s/Mpc

From the two main methods available to measure the Hubble Constant, scientists end up with 67.4 km/s/Mpc and 73.4 km/s/Mpc. We’ve all dealt with mathematical variances like this. Our intuition tells us that with a bit more study, the numbers will meet in the middle somehow.

That’s not what’s been happening. The more cosmologists discover and the better the instruments they use, the more the two numbers stubbornly resist resolving.

The analysis from the team from Cornell offers another point of view on the divergence. Their study, again based on the Cosmic Microwave Background, included a new estimate of the exact value of the Hubble Constant.

Consistent with the Figure from the Planck Satellite Team

The answer the Cornell researchers ended up with is 67.6 km/s/Mpc. Their result is consistent with the 67.4 km/s/Mpc figure, which is also from the Planck Satellite team.

That might seem to leave the 73.4 km/s/Mpc calculation looking like an outlier. It’s based on measuring the redshift in the light from distant galaxies.

Still, there are also multiple studies based on measuring galaxies that support the 73.4 km/s/Mpc figure just as well. There now seems to be more to this variance than meets the eye.

“May Be on the Verge of a New Discovery in Cosmology”

Co-author Michael Niemack explains, “The growing tension between these distant versus local measurements of the Hubble constant suggests that we may be on the verge of a new discovery in cosmology that could change our understanding of how the Universe works.” Instead of settling the difference between the two broad approaches, we may need to find out if there’s something else at work that somehow keeps them separate.

To fill the gaps in our story of the beginning and the end of our Universe, we need to pin down its exact age. From that, we can hone in on the rate at which it expands. That should allow us to confirm, once and for all, exactly how space and time will come to an end in the far-off future.

Connection with Our Place in the Universe

This knowledge will renew humanity’s lost connection with our place in the Universe and in Nature. For many of us, this has the potential to restore a sense of meaning based on scientific knowledge.

The next steps for the Atacama Cosmology Telescope involve producing even higher definition images of the Cosmic Microwave Background and more accurate calculations on the age of the Universe. Beyond that, the telescope can investigate other anomalies in the Standard Model of Cosmology.

We always have more to learn if we dare to know.
Learn more:
New View of Nature’s Oldest Light Adds Twist to Debate Over Universe’s Age
The Atacama Cosmology Telescope: A Measurement of the Cosmic Microwave Power Spectra at 98 and 150 GHz
The 5 Big Questions We Need Cosmology to Answer
Hubble Constant: How Fast are We Going
Are We Inside a Hubble Bubble?

Originally published at https://daretoknow.ca on July 21, 2020.