LISA will discover the invisible! How cool is that? LISA is taking what sounds like science fiction and turning it into reality with intense scientific thinking and clever engineering.

"... a cartwheeling triangle of laser beams will measure wiggles in the fabric of spacetime ..."

I mean really — a cartwheeling triangle of laser beams will measure wiggles in the fabric of spacetime from the densest objects in the universe merging together at the earliest epochs? Does that sound reasonable to you? Well, it's real and it's happening! My greatest excitement is for the total mysteries we will detect — gravitational waves from completely unknown sources. The universe is vast and weird, and I think it's likely that something invisible to the eye will speak in gravity, and we will have NO IDEA what it is. That's the frontier of science and I'm so glad to be on board.

The first extensive studies of a gravitational wave mission in space were carried out in 1989-1990 under the NASA Astrotech 21 program.

"...provide unique new information on mergers involving intermediate mass and larger black holes..."

Even at that time, it was clear that such a mission would be able to provide unique new information on mergers involving intermediate mass and larger black holes at high redshifts, as well as more accurate tests of general relativity. Combining the massive black hole merger information with optical and x-ray observations of the formation and growth of early galaxies seems very likely to provide an explanation of how some black holes in active galactic nuclei can grow to masses of 10 billion solar masses at redshifts of about 7. This information appears to be needed in order to understand the close relationship observed between the mass of the black holes in many galaxies and the central mass of the galaxies.

The first detection of gravitational waves was a monumental achievement that crowned fifty years of experimental and theoretical work. At the same time, it was just the beginning of a new era in astronomy, and LISA is the fulfillment of that vision.

"...LISA may well revolutionize our understanding of physics and astrophysics."

LISA is an ambitious astronomical observatory for new populations of low-frequency gravitational wave sources, and a unique space-based laboratory for gravity and theoretical physics. LISA will allow us to understand massive black holes - the simplest macroscopic objects in the Universe - with unprecedented precision, explore subtle details of their cosmic collisions, reveal how the growth of black holes is related to the structure formation in the early universe, and possibly shed light on the nature of dark matter and dark energy. In the past, opening new observational windows has often led to unexpected discoveries. If history serves us, LISA may well revolutionize our understanding of physics and astrophysics.

LISA is an opportunity to see the Universe in a new way. Binary white dwarfs are among the most prolific sources of gravitational waves. White dwarfs emit light.

"... enables measurements beyond what can be done with light or gravity alone..."

With optical telescopes, we can measure their radius (from eclipses), distance (from parallax), and orbital motion (from spectroscopy). But to measure their most fundamental parameter — mass — requires gravity. Combining light and gravity enable measurements beyond what can be done with light or gravity alone, like measuring how white dwarfs tidally heat up as they come into merger. Binary white dwarfs are thus “multi-messenger” laboratories of the future, an opportunity to see with both light and gravity.

What's so great about LISA? LISA will "hear" colliding supermassive black holes from across the Universe and search for the faint vibrations of spacetime left over from the Big Bang.

"LISA will 'hear' colliding supermassive black holes from across the Universe..."

As a cosmologist, both of these headlines grab my attention. I am excited about the prospect of standard-siren probes of cosmic expansion at deep redshift, and searches for a stochastic gravitational wave background arising from new physics at TeV energy scales and above.

LISA will open a new window into the astrophysics of the objects that I have been studying throughout my career: supermassive black holes and compact binary stars.

"...LISA will detect signals that we never suspected..."

This is quite exciting and intriguing because we will be able to see these objects with new eyes. There is also an enormous potential for new discoveries because LISA will detect signals that we never suspected, perhaps uncovering new populations of astrophysical objects or new unexpected behavior by objects we thought we had figured out.

LISA is an exciting opportunity to the study the Universe in a completely new way. It will improve our understanding of general relativity and space-time. We will learn about white dwarf binaries across the Galaxy, and about supermassive black holes across the Universe.

"...the dark ages of the Universe, an epoch unreachable by traditional electromagnetic astronomy..."

I am most interested in learning about how supermassive black holes formed and grew across cosmic time. LISA will allow us to learn this in the dark ages of the Universe, an epoch unreachable by traditional electromagnetic astronomy. It is exciting to think about the ways in which LISA will teach us about the smallest and largest black holes in the Universe.

It is difficult not to be awed and excited by the prospect of the LISA constellation orbiting the Sun, and listening in on gravitational waves from massive black holes — including some from the earliest stages of structure formation, possibly beyond the distance of any objects found by any traditional telescopes.

"What better time to be a practicing astrophysicist!"

LISA will expand our gravitational waves frequency coverage, and deliver new science ranging from compact massive stellar objects to cosmology in fundamentally new ways. What better time to be a practicing astrophysicist!

LISA is a mission that, from the minute it starts observing, will fundamentally change astronomy. For the first time, we'll be able to detect the hum of millions of binary white dwarfs throughout the Milky Way, even on the other side of the galaxy where light can't penetrate.

"...from the minute it starts observing, [LISA] will fundamentally change astronomy."

We'll be able to witness the birth of supermassive black holes, even in the Dark Ages 100 million years after the Big Bang. And my favorite: intermediate mass black holes, which we suspect exist but have never been seen before. LISA will be a game-changer, and that's why I love it. I can't wait to find out what LISA will discover!

LISA fascinates me on both on the technological and astrophysical fronts. The instrument itself is so cool because it is a triangle of laser-shooting space-crafts that are also precisely balancing gold cubes in freefall.

"...a triangle of laser-shooting spacecraft ... precisely balancing gold cubes in freefall..."

The forces used to stabilize these cubes are less than that of a mosquito standing around. Once it is flying, we will be learning about the most massive black holes ever created in the entire universe. I am excited to learn about what we see when things fall into these super-duper gigantic black holes. I am hoping that we will see deviations from General Relativity and need to figure out this new puzzle. It is all very exciting!

No human has ever been farther from Earth than the Moon, and our robotic explorers have barely been farther. Yet despite that fact, we have learned much about the Universe through ingenuity and clever use of technology that greatly expands our senses beyond Earth.

"... ingenuity and clever use of technology that greatly expands our senses beyond Earth..."

LISA is one of the most remarkable extensions of that simple idea, allowing us to probe the distant Cosmos in ways that no human sense was ever designed to. It will dramatically change our perceptions about the Cosmos, helping us understand how the Universe has grown and evolved.

Black holes are the most enigmatic inhabitants of the invisible universe. Once considered mere mathematical curiosities, exact solutions of Einstein’s tidy field equations, they have become real. Black holes big and small, appear to be literally littered everywhere in the universe. Once considered marginal in the grand cosmic scheme of structure formation, they are center stage and fundamentally shape galaxies. The closest we will get to “see” distant black holes will be from the tremors in space-time – gravitational waves - their collisions will generate.

"...these objects once considered mere mathematical curiosities ... have become real."

LISA will open this new window into the universe revealing distant supermassive black holes, and the first black hole seeds that we believe grew from rapidly crashing into each other. Having worked on tracing the growth and assembly history of black holes over cosmic time, and in particular trying to pin down the role of mergers, I feel very excited at the prospect of data from LISA that stands to revolutionize our understanding. I am thrilled and grateful to have the opportunity to contribute scientifically to this amazing mission.

LISA is one of the most ambitious space missions ever designed, enabling groundbreaking research ranging from collisions of super massive black holes to echoes of the earliest moments in the history of the universe.

"...from collisions of super massive black holes to echos of the earliest moments..."

As a physicist in the field of cosmology and astrophysics, LISA is a dream! I feel privileged to be part of the NASA LISA Study Team and I am excited to contribute to its success.

Having seen the remarkable insights that are coming from the first peek into the GW domain with LIGO and Virgo,

"...a vital step in understanding more of what can be learned."

it's clear that the LISA mission is a vital step in understanding more of what can be learned. I love LISA for that promise of the science that it, with ground and space GW+EM+Particle detectors, will do in the '30s together, but also for the intriguingly different instrument challenges LISA presents.

Since I was a little girl, I have been interested in gravity, space, time and the universe. It is amazing to be a scientist at a time when we are just beginning to explore the gravitational universe.

"LISA will peer into the dark ages of our universe and provide untold riches for gravitational physicists and astronomers."

Ground based gravitational wave detectors like LIGO and Virgo, have opened a new era in physics and astronomy in which strong-field gravity can be studied and observatories like the Event Horizon Telescope are exploring at the edges of black holes. LISA will peer into the dark ages of our universe and provide untold riches for gravitational physicists and astronomers. It's a golden age and I am so thrilled to be part of it.

Although always determined to be an astronomer, I began my fascination with supermassive black holes as an undergraduate and have never looked back. My very first project was searching for binary supermassive black holes using optical spectroscopy, and the prospect of detecting their footprints in the oscillation of space-time was alluring even then.

"LISA will be able to finally see this dance of giants"

Since the detection of stellar mass black holes merging by LIGO in 2015, it has been clear that LISA will be able to finally see this dance of giants, and help us see how these black holes are first born in the early universe. I am thrilled to be able to contribute scientific perspective to this amazing feat of human ingenuity.

I love LISA because of its combination of the very small (measuring distances in picometers and accelerations in femto-g's) with the unimaginably huge (billion solar mass black holes crashing into one another at the edge of the observable universe).

"...its combination of the very small with the unimaginably huge..."

It also represents a once-in-a-generation opportunity to do something truly new like observe the universe in a way that has never been done before.