Tag Archives: Ethan Siegel

A lighthearted look at the dark universe

Two astronomers recently came independently to the conclusion that the way to figure out the fate of the universe is to build bigger and better telescopes. Prof. Sarah Tuttle of the University of Washington and Dr. Ethan Siegel of the Starts With a Bang blog and podcast both made informative and entertaining presentations about the dark universe at the most recent gathering of Astronomy on Tap Seattle at Peddler Brewing Company in Ballard.

Sarah Tuttle

UW astronomy Prof. Sarah Tuttle spoke at Astronomy on Tap Seattle May 24, 2017 at Peddler Brewing in Ballard. (Photo: Greg Scheiderer)

In her talk titled, “Dark Matter, Dark Energy, and Otters,” Tuttle joked that astronomers are “the universal accountants,” and that right now these bean counters are thinking that 68 percent of the universal energy budget consists of dark energy.

“If I were you, I would be concerned, because I both just told you that most of the universal energy budget is dark energy, and we don’t know what it is,” Tuttle said. “Dark matter we can measure and observe, but we don’t know what that is, either.”

There are a lot of theorized particles that could be in the dark-matter mix, but Tuttle said we don’t really understand them yet.

“We are in the process of measuring them and trying to figure out what it could actually be that is dark matter, how it is interacting with everything around it, because it is the dominant form of matter in our universe,” she said. We’re even more in the dark about dark energy.

“We are able to pin down that dark energy exists, that the universe is expanding and accelerating, and we’re not yet quite sure how to explain that,” Tuttle said.

How do we know?

Three experiments have helped reveal dark energy. Observations of the cosmic microwave background and type 1a supernovae have shown us that the universe is expanding. Tuttle is involved with a project called HETDEX—the Hobby Eberly Telescope Dark Energy Experiment—using a 10-meter telescope in West Texas. HETDEX is taking spectra of faint, young galaxies that are Lyman-alpha emitters to try to detect baryon acoustic oscillations. Huh?

“We’re using the clustering of a particular kind of galaxy to measure the distortion of spacetime,” Tuttle explained. She said it’s like throwing a grid of lights over a three-dimensional object—the lights will reveal the shape of the object.

“We use these galaxies to show us the shape of spacetime underneath to expose how dark energy changes with time,” Tuttle said. Other efforts like EBOSS and the South Pole Telescope are working on the same problem.

“We use a lot of different techniques to try to figure out what we’re doing to expose what dark energy is,” Tuttle said. “It turns out it’s going to take more beer and more time before we can answer that question.”

Our fate is in dark energy’s hands

Ethan Siegel

Dr. Ethan Siegel of the Starts with a Bang blog and podcast spoke at Astronomy on Tap Seattle May 24. (Photo: Greg Scheiderer)

Siegel’s talk was titled “The Fate of the Universe: After 13.8 billion years, where is everything headed?” He noted that it astronomers once saw three possible scenarios for the future of our universe. It could keep on expanding forever, it could eventually collapse back onto itself, or expansion and gravity could balance out just right for a universe that remains about the way it is.

“That’s what we thought for years and years and decades and decades: the fate of the universe is going to be one of these three,” Siegel said. “The whole field of cosmology, which is my field, was the quest to measure what’s it going to be.”

“They’re all wrong,” he said. Dark energy is the wild card. Siegel pointed out that matter dilutes with the expansion of the universe, and radiation gets weaker; it redshifts. Dark energy? We’re not so sure.

“If there’s any type of energy that’s inherent to the fabric of space, then as space grows this energy is just growing,” Siegel explained. “As your universe grows, it’s like you’re just making more and more of this new type of energy if there’s any non-zero energy to space itself.”

A big assumption

Siegel gave a lengthy description of the fate of the universe, from the boiling oceans of Earth to the last black hole standing. It was all based on the assumption that dark energy is constant. But what if it gets stronger over time? Siegel said that would mean that galaxies and solar systems and the Earth would all get torn apart.

“In the fiery final moments, everything, even the atoms that made you up, even the nuclei that made you up, would be ripped apart as well,” he said. “That fate is known as the Big Rip, and it’s possible. I don’t think it’s right, but you can’t be sure unless you measure it.”

Dark energy could get weaker, too, and that could lead to the opposite outcome, a big crunch.

“That’s something we could also measure,” Siegel said. “We haven’t constrained it well enough to know that it won’t rip or that it won’t turn around and crunch again. The way we’re going to find out is through bigger and better telescopes and observatories.”

HETDEX is a big part of that, Siegel noted, and said that the ESA’s Euclid telescope will measure dark energy to better precision than ever before. NASA’s WFIRST (Wide Field Infrared Survey Telescope), scheduled to launch in mid-2020, and the Large Synoptic Survey Telescope, under construction in Chile with hopes of being fully operational by 2022, will also make key contributions to this work.

“If you think that this stuff is fun, I’m telling you it’s going to get even better in the 2020s,” Siegel concluded. Stay tuned.

If you couldn’t attend AOT Seattle, you can watch online! In May they live-streamed the event for the first time.

More reading:

  • Article about BOSS from a 2016 Astronomy on Tap
  • Article about the LSST from a 2016 Astronomy on Tap
  • Siegel’s talk about the expanding universe given to Rose City Astronomers in February
  • Siegel’s talk about the discovery of gravitational waves given to RCA in 2015
  • Siegel’s book, Beyond the Galaxy

The expanding universe: discovery, controversies, and hope

We’ve known that there is a universe outside the Milky Way, and that it is expanding, for less than a century.

“Throughout the entire history of the universe, of knowing it’s expanding, there have been a tremendous number of controversies over it, and there’s still one that persists today,” said astrophysicist and author Ethan Siegel. Siegel, author of Beyond the Galaxy: How Humanity Looked Beyond Our Milky Way and Discovered the Entire Universe (World Scientific Publishing, 2015), spoke at last week’s meeting of the Rose City Astronomers in Portland, Oregon.

The controversy actually goes back to before the expansion was observed, to Albert Einstein. His equations describing general relativity suggested that gravity would collapse the universe onto itself, and as he believed the universe was static, he threw in a “cosmological constant” to push back against gravity. Einstein later called that his biggest blunder, though some wanted to let him off the hook for it when dark energy was proposed to do the exact same thing.

“I am here to tell you that this was Einstein’s reasoning and throwing this in there when he did was a super big blunder because the universe isn’t static,” Siegel said. Einstein should have trusted his theory, he said, and taken it to the next step.

The universe is expanding

By the 1920s Edwin Hubble observed a Cepheid variable star in the Andromeda “nebula” that indicated that it was far outside the Milky Way and a galaxy in its own right. Astronomers were also studying redshift as an indication for the speeds at which galaxies were receding from us. Siegel explained that through this, Hubble determined that the universe was expanding at a rate of 600km/sec/Mpc (kilometers per second per megaparsec.) This became the Hubble constant. But it wasn’t so constant.

Siegel noted that, knowing the size and expansion rate of the universe, you can figure its age by running the numbers in reverse and going back to the beginning, to the Big Bang. The resulting calculation determined that the universe was about two billion years old. Geologists at the time had already pegged the age of the Earth as at least four billion years.

“This was a problem for Hubble, because the universe isn’t allowed to be half the age of the Earth,” Siegel noted. “Either this expansion rate is wrong and this age for the universe is wrong, or the age of the Earth is wrong.”

It turns out that Hubble’s main mistake was in figuring that all variable stars are alike. Siegel said Walter Baade came along in the 1940s and discovered that they are not. Finding that most of the Cepheids Hubble had looked at were non-classical, they re-ran the numbers from Hubble’s data.

“As you accumulate more knowledge, as you accumulate a better understanding of what you’re actually loooking at, you can go back and get more useful science out of this data,” Siegel said. This second look doubled the distance to these stars and reduced the value for the Hubble constant to 270km/sec/Mpc. This in turn put the age of the universe at five billion years.

“That’s better,” Siegel noted. “The universe is older than Earth. That’s one problem solved.”

Narrowing it down


Dr. Ethan Siegel, creator of the “Starts With a Bang” blog, gave a talk about the age and size of the universe to the Rose City Astronomers February 20. Photo: Greg Scheiderer.

As time went on astronomers developed the “distance ladder” for determining the vast distances in the universe. You first measured the distance to Cepheid variables within the Milky Way, then gauged the distances to other galaxies using Cepheids spotted there. Type 1a supernovae could be spotted really far out. As we learned more about the stars we got a little better at figuring distances.

Things got really interesting in the 1960s, according to Siegel. We discovered that we could determine the ages of stars by measuring their color and brightness. The Hertzsprung–Russell diagram told us that the oldest stars were between 14 billion and 16 billion years old, significantly older than the age of the universe determined by Baade. Astronomer Allan Sandage, who as a graduate student was an assistant to Hubble, came along and said you needed two things to make the universe that old: it had to be low enough in density to make a vast expansion, and the expansion rate had to be low.

Dueling Hubble constants

This, Siegel said, was where the controversy came in. Sandage said the expansion rate would have to be between 50-60km/sec/Mps. Rival astronomer Gérard de Vaucouleurs of France put it at around 100km/sec/Mpc. The race was on to make observations to see which group was right. Amazingly enough, each group’s observations matched up with what they thought the answer would be.

“This just goes to show that you cannot have the same people making the same measurements and trust them,” Siegel said. “This is why you need independent confirmation.”

It turns out Sandage and de Vaucouleurs were both wrong. There’s still no agreement on the right answer, but the disagreements are getting closer together. Sigel said the Hubble Space Telescope’s improvements in measuring the size of the universe return a value of 74±2km/sec/Mpc. The Planck mission’s observations of the cosmic microwave background radiation suggest 67±1km/sec/Mpc.

“There is a fight over the results like there always seems to be, because we are scientists and we cannot agree on anything,” Siegel said. “That is good, because questioning is what keeps us moving forward and what keeps us learning more.”

“The way we’re going to get there is with more and better data,” he added.

Better data

The better data will come from missions such as the European Space Agency’s Gaia, the James Webb Space Telescope, WFIRST, and the Large Synoptic Survey Telescope, which combined might improve our parallax measurements of cosmic distances by a factor of ten. We might also weed out faulty assumptions in the earlier work or get more accurate insights into the balance between matter and dark energy in the universe.

“If we can wait until the next decade, we might see that 74 number come down, we might also see the 67 number come up,” Siegel said. “The point is uncertainties are going to be reduced by more and better data.”

Siegel said that right now it’s pretty much agreed that the universe is about 13.8 billion years old and consists of about 30 percent matter and 70 percent dark energy. But the miniscule pluses or minuses can lead to huge fights.

“When that data comes in at last we will know exactly how fast our universe is expanding, how old it is, and what it all means for both our cosmic origins and our cosmic fate,” Siegel concluded. “That’s pretty good stuff.”

In the podcast linked below Siegel covers much of the topic matter of this article and his talk. His new book, Treknology: The Science of Star Trek from Tricorders to Warp Drive (Voyageur Press, 2017), is scheduled for release in October.


Search for meaning continues

There is a great menu of interesting talks on this week’s calendar, including three with astronomy themes at a weekend event at Seattle University.

Search for Meaning FestivalSeattle University’s annual Search for Meaning Festival will be held on the university campus all day Saturday, February 25. The festival is a community event dedicated to topics surrounding the human quest for meaning and the characteristics of an ethical and well-lived life. It draws more than 50 authors and artists who will give interactive presentations. Three of these sessions are on astronomy-related topics.

At 9 a.m. Father George Coyne, SJ, former director of the Vatican Observatory and author of Wayfarers in the Cosmos: The Human Quest for Meaning (Crossroad 2002), will discuss the history of the evolution of life in the cosmos. Coyne’s thesis is that this history may lead us to a deeper understanding of what many secular physicists say themselves about the cosmos: that a loving creator stands behind it.

At 10:45 a.m. Margot Lee Shetterly, author of the book Hidden Figures: The American Dream and the Untold Story of the Black Women Mathematicians Who Helped Win the Space Race (William Morrow, 2016), on which the current hit film is based, will give one of the keynote addresses at the festival. Shetterly will talk about race, gender, science, the history of technology, and much else. Reservations for Shetterly’s talk are sold out.

At 12:45 p.m. Marie Benedict, author of The Other Einstein (Sourcebooks Landmark, 2016), will explore the life of Mileva Maric, who was Albert Einstein’s first wife and a physicist herself, and the manner in which personal tragedy inspired Mileva’s possible role in the creation of Einstein’s “miracle year” theories.

Check our post from December previewing the festival, and look at the trailer video below. Tickets to the festival are $12.50 and are available online.

Siegel at Rose City

Author and astrophysicist Ethan Siegel will be the guest speaker at the monthly meeting of the Rose City Astronomers in Portland at 7:30 p.m. Monday, February 20. Siegel will talk about his book Beyond the Galaxy: How Humanity Looked Beyond Our Milky Way and Discovered the Entire Universe (World Scientific Publishing, 2015). He’ll examine the history of the expanding universe and detail, up until the present day, how cutting-edge science looks to determine, once and for all, exactly how the universe has been expanding for the entire history of the cosmos. Siegel is an informative and engaging speaker; check our recap of his talk from last year about gravitational wave astronomy.

AoT Seattle and an app for simulating the universe

AoT FebruaryAstronomy on Tap Seattle’s monthly get-together is set for 7 p.m. Wednesday, February 22 at Peddler Brewing Company in Ballard. Two guest speakers are planned. Dan Dixon, creator of Universe Sandbox² will give an introduction to the app, an accessible space simulator that allows you to ask fantastical what-if questions and see accurate and realistic results in real-time. It merges real-time gravity, climate, collision, and physical interactions to reveal the beauty of our universe and the fragility of our planet. University of Washington professor in astronomy and astrobiology Rory Barnes will talk about “Habitability of Planets in Complicated Systems.” It’s free, except for the beer.

TAS public night

Tacoma Astronomical SocietyThe Tacoma Astronomical Society plans one of its public nights for 7:30 p.m. Saturday, February 25 at the Fort Steilacoom campus of Pierce College. The indoor presentation will be about the zodiac. If the skies are clear they’ll set up the telescopes and take a look at what’s up.

Futures file

You can scout out future astronomy events on our calendar. We’ve recently added several events scheduled at the Museum of Flight, including:

Up in the sky

There will be an annular solar eclipse on Sunday, February 26, but you’ll have to be in South America or Africa to see it. This Week’s Sky at a Glance from Sky & Telescope magazine and The Sky This Week from Astronomy offer more observing highlights for the week.


Club events and planetarium shows on tap for this week

The first weekend in December is heavy with club events, star parties, and planetarium shows. Here’s what’s on the calendar for the coming week:

Club gatherings

Spokane Astronomical SocietyIn December many astronomy clubs opt out of a formal meeting and instead hold a banquet or other more social gathering. The Spokane Astronomical Society plans its annual potluck dinner for 6 p.m. Friday, December 2 at the Riverview Retirement Community. A guest speaker will follow the dinner at 7:30. Dr. John Buchanan, a professor of geology at Eastern Washington University, will talk about catastrophic outburst flooding that have occurred on Earth and Mars through geologic time. He will examine how the “Ice Age Floods” in eastern Washington compare with various large floods both on Earth and Mars.

Seattle Astronomical SocietyThe Seattle Astronomical Society plans its free monthly public star parties for 6 p.m. Saturday, December 3 at two locations: Green Lake in Seattle and Paramount Park in Shoreline. Poor weather will mean cancellation of the events, so watch the club’s website and social media for updates.

Tacoma Astronomical SocietyThe Tacoma Astronomical Society will hold one of its free public nights at 7:30 p.m. Saturday, December 3 at the Fort Steilacoom campus of Pierce College. The all-weather program will be about selecting gift telescopes, binoculars, and other astronomy gear. (We covered that topic, too last week!) If the weather is good they’ll also put their gear into action for some celestial observing.

Planetarium shows

Planetaria have no trouble with cloudy weather! There are several shows on the docket for the week.

The University of Washington planetarium will host three free shows on Friday, December 2 at 5:30, 6:30, and 7:30 p.m. Reservations for all three times were snapped up quickly, but you can watch this site to see if tickets become available.

Pacific Planetarium in Bremerton will host its First Friday Sky Walk shows December 2, with a presentation every half-hour between 5 p.m. and 7:30 p.m. The shows look at what’s up in the sky for the coming month.

There are a variety of shows suitable for all ages every day at the Willard Smith Planetarium at the Pacific Science Center. You’ll find their complete schedule on our calendar page.

Futures file

You can scout out future astronomy events on our calendar. New additions to the calendar this week include:

Up in the sky

Venus and the Moon make a nice pairing on the evening of December 3. This Week’s Sky at a Glance from Sky & Telescope magazine and The Sky This Week from Astronomy offer more observing highlights for the week.


The universe is big, even in small spaces

The universe is pretty vast even in confined spaces. That was the lesson given on opposite ends of the size scale at the most recent Astronomy on Tap Seattle event hosted at Hilliard’s Beer Taproom by University of Washington graduate students in astronomy.

Ethan Kruse

UW astronomy graduate student Ethan Kruse said the universe is a big place, and it will take some technological advances to reach Alpha Centauri in 20 years. Photo: Greg Scheiderer.

Grad student Ethan Kruse was all set to give a talk that concluded we would never even get out of our solar system because it is way too big. Then a few weeks before the talk Stephen Hawking and friends announced their plan for getting all the way to neighboring star Alpha Centauri in 20 years through a project called Breakthrough Starshot.

“If I’m disagreeing with Stephen Hawking,” Kruse recalled thinking, “I should probably stop for a minute and reevaluate my thesis.”

Kruse remained on point about the mind-boggling scale of the universe. He said that if our Sun was the size of a basketball sitting on the stage of Hilliard’s, Earth would be the size of a sesame seed in the back of the room, 84 feet away, and the orbiting Moon would be the size of a grain of salt. At this scale Jupiter would be a golf ball on the Ballard Bridge and Pluto would be a grain of salt about a kilometer away—about the distance to Bad Jimmy’s Brewing Company, which served as the venue for Astronomy on Tap Seattle for its first year. Alpha Centauri, in this set-up, is some 4,400 miles away—in London or Tokyo.

Kruse pointed out that the fastest spacecraft we have built so far, New Horizons, took a decade to get to Pluto.

“We went from Hilliard’s to Bad Jimmy’s in ten years,” he observed. “Don’t worry guys, we’re going to go to London in 20 years!”

The idea behind Starshot is that a super-light craft with a light sail could be accelerated by lasers to up to 20 percent of the speed of light. Kruse outlined a litany of technological challenges with the concept, including the ability to generate sufficient laser power, creating an adequately reflective material for the sails, being able to accurately aim the lasers at great distances, and shielding the craft from possible collisions with space debris. Still, he concluded, the idea is worth exploring, especially since the same technology could be used to explore the solar system more quickly.

“This is honestly the most realistic thing that anyone has proposed so far for getting to any other star system,” Kruse said.

It will, however, take a great deal of research and development.

“Don’t necessarily count on this before you die,” Kruse concluded. “Space is big.”

Jessica Werk

UW astronomy Prof. Jessica Werk says your atoms took quite a journey to become you. Photo: Greg Scheiderer.

Professor Jessica Werk, one of the newest hires onto the astronomy faculty at the University of Washington, also used sports equipment to illustrate her talk, “The History of You: The Rather Tumultuous Past of the Atoms in Your Body.” Werk pointed out that atoms are mostly empty space. If the nucleus of an atom were the size of a baseball, the nearest electrons would be a football field away.

After the Big Bang the universe was mostly light atoms: hydrogen and helium and a few others. Where did the carbon and calcium and other heavier stuff we’re made of come from?

“All evidence suggests that these atoms were fused in the cores of very, very massive stars twelve-and-a-half billion years ago,” Werk said. “Since then they have been on an absolutely crazy, long, sometimes violent journey to end up in your body 93 million miles from the Sun on this speck named Earth.”

Those atoms took a somewhat circuitous route to get here.

“Sixty percent of the atoms in your body we at one point outside of the galaxy in the circumgalactic or intergalactic medium,” Werk said. We don’t really know how they got here, but the best theory is that the atoms tend to cool off, and the gas rains back down on the galaxy, collapsing in star formation or becoming part of the debris disk out of which planets form.

There’s some mind-bending scale at the atomic level, too. Werk pointed out that there are 1023 atoms in a breath of air.

“Each breath-full of air contains more atoms than the number of breath-fulls of air in the entire Earth’s atmosphere,” she said. “What that means is that it is very likely that the last breath of air you just took contained at least one oxygen atom from the first breath of air that you ever took as a human being on planet Earth.”

That reminds us of a recent post by Ethan Siegel on the blog Starts With a Bang, in which he concluded that we all probably share atoms that were once part of King Tut or any other historical figure you might name.

AOT crowd

Astronomy on Tap Seattle outgrew Bad Jimmy’s, and pretty well packed the larger Hilliard’s at its first event there in April. Photo: Greg Scheiderer.

“The matter that makes up your physical body is part of a huge universe that is continually evolving and recycling the material in it into new forms,” Werk concluded.

The next Astronomy on Tap Seattle event is set for 7 p.m. Wednesday, May 25 at Hilliard’s. Astronomy Prof. Emily Levesque and graduate student John Ruan will give talks about some of the strangest celestial objects ever discovered or theorized. People outnumbered seats at the April event, and so the organizers suggest that you can bring a lawn chair and create your own premium seating.


Gravitational wave discovery ushers in new era in astronomy

“This is beginning a new era in astronomy,” said Ethan Siegel about the publication in February of a paper announcing that scientists had detected gravitational waves. Siegel has taught physics and astronomy at Lewis & Clark College and the University of Portland in Portland, Oregon. He is creator of the science blog Starts With a Bang, and is the author of Beyond the Galaxy: How Humanity Looked Beyond Our Milky Way and Discovered the Entire Universe (World Scientific, 2015). Siegel gave a talk at this month’s meeting of the Rose City Astronomers in Portland about what he calls the discovery of a lifetime.

Dr. Ethan Siegel, creator of the "Starts With a Bang" blog, gave a talk about the discovery of gravitational waves to the Rose City Astronomers April 18. Photo: Greg Scheiderer.

Dr. Ethan Siegel, creator of the “Starts With a Bang” blog, gave a talk about the discovery of gravitational waves to the Rose City Astronomers April 18. Photo: Greg Scheiderer.

“This was something, when it was first proposed, that was really taken to be a preposterous consequence of a theory and something that we never really thought we were going to be able to test,” Siegel said. “We have gone in 101 years from pure theory to concrete, direct detection of gravitational waves.”

Einstein’s theory of relativity states that mass and energy bend spacetime, and that’s why objects orbit each other. Relativity explained anomalies in the orbits of planets in our solar system, but Siegel said there is an “extra weird” effect because the orbits decay.

“Another consequence of Einstien’s relativity is that as things spiral in, and it takes a long time to do, but as they do they emit a special type of radiation; they emit radiation that goes through the fabric of space itself,” Siegel said. “This is gravitational radiation.”

It takes way too long for that to happen here in the solar system. For Earth’s orbit to decay completely and merge with the Sun would take 10150 years, according to Siegel. He said we’ll have to look elsewhere to see the effects happen on human-length time scales.

“You need to find heavy masses; heavier mass in relativity means a stronger effect,” Siegel said. “You need them to have small distances, where small distance is a few kilometers, not a few million miles. And you need them to orbit at fast speeds, where fast is kind of close to the speed of light.”

Luckily these conditions exist. Black holes, neutron stars, and pulsars can do the trick; the gravitational waves detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) last fall were generated by merging black holes. One of those black holes started out at 36 solar masses and the other at 29. After the merger they weighed in at 62 solar masses. That’s simple arithmetic: 36+29=65; what happened to the other three solar masses? Siegel said, oddly enough, this was a prediction by Einstein as well. It’s the flip side of e=mc2.

“When these two black holes merged, three solar masses, about five percent of the total mass, was converted into pure energy,” he said. “That energy is the gravitational radiation and is why we here on Earth were able to detect this huge event of two black holes merging from over a billion light years away.”

Siegel is amazed that we were able to figure the mass, spin rate, merging speed, mass loss and other characteristics of these distant objects.

“We learned all of this information from one 20-millisecond signal that moved two laser arms by less than 10-18 meters,” he marveled. “What I’d say we have now is a whole new way to discover our universe.”

Siegel, an entertaining and informative speaker, is scheduled to give another talk at the October 2016 meeting of Rose City Astronomers. He will discuss his book Beyond the Galaxy.

That way is improving rapidly. The LIGO detectors at Hanford, Washington, and Livingston, Louisiana, are being tweaked to even greater sensitivity. New detectors are planned for Italy, Japan, and India. Siegel said the ultimate would be to build three huge LIGO detectors in space, forming an equilateral triangle in Earth’s orbit and having detector arms hundreds of millions of kilometers long.

“If you do that, you can not only watch things merge with supermassive black holes, you can find mergers of ultramassive black holes,” Siegel said. We might even be able to spot gravitational waves from cosmic inflation within the light of the cosmic microwave background. Siegel said if that happens, it would prove that gravity is a quantum force.

“There’s no way to make these fluctuations unless gravity is inherently a quantum force,” he explained. “The process that makes these fluctuations is a quantum process.”

Siegel said it’s a thrilling time to be involved in astronomy.

“This is the first time we’ve seen something astronomical without using a telescope or light of any type,” he said. “This is the dawn of astronomy beyond light-gathering telescopes.”