Photo of Andrea Ghez

Andrea Ghez wins 2020 Nobel Prize in physics

Photo of Andrea Ghez

Andrea Ghez, UCLA’s Lauren B. Leichtman and Arthur E. Levine Professor of Astrophysics, has been awarded the 2020 Nobel Prize in physics. Photo Credit: Elena Zhukova

Andrea Ghez, UCLA’s Lauren B. Leichtman and Arthur E. Levine Professor of Astrophysics, today was awarded the 2020 Nobel Prize in physics.

Ghez shares half of the prize with Reinhard Genzel of UC Berkeley and the Max Planck Institute for Extraterrestrial Physics. The Nobel committee praised them for “the discovery of a supermassive compact object at the centre of our galaxy.” The other half of the prize was awarded to Roger Penrose of the University of Oxford “for the discovery that black hole formation is a robust prediction of the general theory of relativity.”

In July 2019, the journal Science published a study by Ghez and her research group that is the most comprehensive test of Albert Einstein’s iconic general theory of relativity near the monstrous black hole at the center of our galaxy. Although she concluded that “Einstein’s right, at least for now,” the research group is continuing to test Einstein’s theory, which she says cannot fully explain gravity inside a black hole.

Ghez studies more than 3,000 stars that orbit the supermassive black hole. Black holes have such high density that nothing can escape their gravitational pull, not even light. The center of the vast majority of galaxies appears to have a supermassive black hole, she said.

“I’m thrilled and incredibly honored to receive a Nobel Prize in physics,” said Ghez, who is director of the UCLA Galactic Center Group. “The research the Nobel committee is honoring today is the product of a wonderful collaboration among the scientists in the UCLA Galactic Center Orbits Initiative and the University of California’s wise investment in the W.M. Keck Observatory.

“We have cutting-edge tools and a world-class research team, and that combination makes discovery tremendous fun. Our understanding of how the universe works is still so incomplete. The Nobel Prize is fabulous, but we still have a lot to learn.”

UCLA Chancellor Gene Block lauded Ghez for her accomplishments.

“The UCLA community is exceedingly proud of Professor Ghez’s achievements, including this extraordinary honor,” Block said. “We are inspired by her research uncovering the secrets of our universe and its potential to help us better understand the cosmos.”

David Haviland, chair of the Nobel Committee for Physics, said: “The discoveries of this year’s Laureates have broken new ground in the study of compact and supermassive objects. But these exotic objects still pose many questions that beg for answers and motivate future research. Not only questions about their inner structure, but also questions about how to test our theory of gravity under the extreme conditions in the immediate vicinity of a black hole.”

Ghez and her team have made direct measurements of how gravity works near a supermassive black hole — research she describes as “extreme astrophysics.”

Einstein’s general theory of relativity is the best description of how gravity works. “However, his theory is definitely showing vulnerability,” Ghez said in 2019. “[A]t some point we will need to move beyond Einstein’s theory to a more comprehensive theory of gravity that explains what a black hole is.”

Less than two months after her publication in Science, she and her research group reported in Astrophysical Journal Letters the surprising finding that the supermassive black hole is having an unusually large meal of interstellar gas and dust — and they do not yet understand why.

“We have never seen anything like this in the 24 years we have studied the supermassive black hole,” she said at the time. “It’s usually a pretty quiet, wimpy black hole on a diet. We don’t know what is driving this big feast.”

In January 2020, her team reported the discovery of a new class of bizarre objects — objects that look like gas and behave like stars — at the center of our galaxy, not far from the supermassive black hole.

Ghez and her team conducted their research at the W.M. Keck Observatory in Hawaii. They are able to see the impact of how space and time get comingled near the supermassive black hole, which is some 26,000 light-years away.

“Making a measurement of such fundamental importance has required years of patient observing, enabled by state-of-the-art technology,” Richard Green, director of the National Science Foundation’s division of astronomical sciences, said in 2019.

“Andrea is one of our most passionate and tenacious Keck users,” Keck Observatory director Hilton Lewis said, also in 2019. “Her latest groundbreaking research is the culmination of unwavering commitment over the past two decades to unlock the mysteries of the supermassive black hole at the center of our Milky Way Galaxy.”

The National Science Foundation funded Ghez’s research for the past 25 years. More recently, her research has also been funded by the W.M. Keck Foundation, the Gordon and Betty Moore Foundation and the Heising-Simons Foundation, Lauren Leichtman and Arthur Levine, and Howard and Astrid Preston.

In 1998, Ghez answered one of astronomy’s most important questions, helping to show that a supermassive black hole resides at the center of the Milky Way galaxy. The question had been a subject of much debate among astronomers for more than a quarter of a century.

Ghez helped pioneer a powerful technology called adaptive optics, which corrects the distorting effects of the Earth’s atmosphere in real time and opened the center of our galaxy as a laboratory for exploring black holes and their fundamental role in the evolution of the universe. With adaptive optics at the Keck Observatory, she and her colleagues have revealed many surprises about the environments surrounding supermassive black holes, discovering, for example, young stars where none were expected and a lack of old stars where many were anticipated.

In 2000, Ghez and her research team reported that for the first time, astronomers had seen stars accelerate around the supermassive black hole. In 2003, she and her team reported that the case for the Milky Way’s black hole had been strengthened substantially and that all of the proposed alternatives could be excluded.

In 2005, Ghez and her colleagues took the first clear picture of the center of the Milky Way, including the area surrounding the black hole, at the Keck Observatory.

Ghez has earned numerous honors for her research, including election to the National Academy of Sciences and the American Academy of Arts and Sciences; she was the first woman to receive the Royal Swedish Academy of Sciences’ Crafoord Prize, and she was named a MacArthur Fellow in 2008. In 2019, she was awarded an honorary degree by Oxford University.

She earned a bachelor’s degree in physics from MIT in 1987 and a doctorate from Caltech in 1992, and she has been a member of the UCLA faculty since 1994. When she was young, she wanted to be the first woman to walk on the moon.

Ghez is the eighth UCLA faculty member to be named a Nobel laureate, joining Willard Libby (chemistry, 1960), Julian Schwinger (physics, 1965), Donald Cram (chemistry, 1987), Paul Boyer (chemistry, 1997), Louis Ignarro (physiology or medicine, 1998), Lloyd Shapley (economics, 2012) and J. Fraser Stoddart (2016). Stoddart was a Northwestern University faculty member when he received the honor, but much of the work for which he was recognized was conducted at UCLA from 1997 to 2008.

In addition, seven UCLA alumni have been awarded the Nobel Prize.

Ghez is also the fourth woman to receive the physics prize, following Marie Curie in 1903, Maria Goeppert Mayer in 1963 and Donna Strickland in 2018.

This article, written by Stuart Wolpert, originally appeared in the UCLA Newsroom.

A photo of three UCLA students studying physics and engaging in their lab work.

Instructors’ foresight leads to remote learning success for physics labs

A photo of three UCLA students studying physics and engaging in their lab work.

Thanks to off-the-shelf kits, UCLA students studying physics could do their lab work in their homes and design their own experiments. (Photo Courtesy of Katsushi Arisaka)

When UCLA announced on March 10 that the final weeks of winter quarter — and later the entire spring quarter — would be taught remotely because of COVID-19, it immediately tested everyone on campus, but in particular students and faculty who had to figure out on the fly new ways to learn and teach.

Adapting was understandably easier for some classes, like introductory courses which could more simply turn a live lecture in a big hall into a video lecture delivered through Zoom. But what about classes built around in-person group work, or the performing arts, or science and engineering labs that require the use of equipment and materials for hands-on learning?

Fortunately for the students taking the Physics 5AL/5BL/5CL series (physics for life sciences majors) or the Physics 4AL/4BL series (physics for scientists and engineers), their professors and teaching assistants in the UCLA Department of Physics and Astronomy were uniquely prepared for this forced period of remote instruction.

For the past few years, the department has explored ways to improve engagement for the 3,000-plus students who take these classes each year by making the labs for these courses more student-oriented. The transition to remote learning made figuring out the best ways to do that more urgent than ever, and the department’s head start on adapting the class to better fit students’ needs helped make the transition much easier.

“The key to giving a satisfying experience to students working remotely is to offer real-time solutions as quick as possible,” said Katsushi Arisaka, professor of physics and astronomy in the UCLA College and also of electrical and computer engineering in the Samueli School of Engineering, who emphasized how much of a team effort this has been. “That’s why we need such a good group of TAs behind the scenes.”

For Arisaka, restructuring these classes has always been about finding new ways to prepare students for future success. He has worked with teaching assistants Javier Carmona, Shashank Gowda, Erik Kramer, Grant Mitts, Pauline Arriaga and many others, to find ways to give students more control over the labs, while introducing them to concepts and skills, such as writing computer code.

To make these lab classes work from home, students needed access to the right tools, which also meant affordable equipment, such as the Arduino UNO Starter kit for Physics 4AL and 4BL and the Snap Circuit Kit for Physics 5CL, which Arisaka and his teaching assistants have been using for a couple of years.

Arduino and Snap Circuit kits provide dozens of basic hardware components that allow those without backgrounds in electronics and programming to create low-cost scientific instruments, to prove chemistry and physics principles, or to get started with programming and robotics. Students have been able purchase these kits online or the UCLA Store and their wide availability has also made the transition easier.

Students were grouped to work together remotely via Zoom breakout rooms from day one. The highlight of the course was to conduct their group final projects during the last three weeks and present the results by Zoom video-recording. It seems the only limit to students’ projects was their imagination.

Projects included: comparing human versus automated coin flips; measuring the effect of music on human reaction time; observing the energy lost by a bouncing ball; predicting the trajectory of basketball shots; comparing use of force across five sports; studying how the shape of a rolling object affects its acceleration as it rolls down an inclined surface and comparing the observations with physics theory.

“Students seem to be enjoying it, and as TAs we enjoy their creativity,” said Gowda, graduate student researcher in UCLA’s Smart Grid Energy Research Center, who noted that these types of ideas will improve student learning even once in-person instruction resumes. “They develop experiments and projects that we wouldn’t even think of.”

While previous versions of the class covered the necessary material, said Kramer, their structure seemed antiquated. “The move to this more modern hardware platform, using the coding language Python, and Arduino, has really inspired students to do amazing final projects,” he said.

According to Carmona, the way these labs were previously run just didn’t capture the imagination of students as much as they should. Speaking on the transition, he says it was a difficult task, but one that was well worth the effort.

Teaching assistant Javier Carmona, left, leads a Zoom class on how to use the Arduino kits.

Teaching assistant Javier Carmona, left, leads a Zoom class on how to use the Arduino kits. (Photo Courtesy of Katsushi Arisaka)

“It required a lot of work to get to where it’s at, but I’m glad we put in the work because now we have hundreds of students who didn’t miss out on a hands-on laboratory they could do at home,” Carmona said.

To make the hands-on, labs-at-home work the instructors “flipped” the class, encouraging students to design and test their own experiments rather than making them follow strict guidelines from teaching assistants and professors. Abandoning the old ways for physics labs proved positive according to student responses.

Among the comments from students provided as part of the course feedback: “You all are doing great, by far the most fun class I have this quarter, thank you for all the effort you guys have been putting into this, I figure it’s got to be really hard putting together a remote lab, but you guys are doing a pretty dang good job :)”

“We are learning marketable skills with Arduino and Python and the course development team is very receptive to feedback and constantly tries to make the class better. Thank you!”

Another change that the group is proud of is asynchronous operation — which allows students to learn at their own pace. This switch has given students flexibility to work at a rate they feel comfortable with, a change that can be beneficial for students who may be struggling with the material.

“The videos demonstrating how to use python and how to set up experiments have been extremely helpful, especially to someone like myself who has no experience with this as I’ve not taken 4AL,” wrote another student.

At the same time, Arisaka said, letting students work at the own pace also allows students who really understand the material to finish their work faster, and he encourages them to go back and help their peers.

Arisaka, who has been teaching physics for more than 30 years, also said it’s time to move away from the notion that students should be competing with one another for grades.

“They can boost their grade if they do better, it has nothing to do with the student next to them, and this message is very important so they can learn something useful,” said Arisaka, who noted that students’ mastery of skills was better than ever this quarter, even though labs were conducted at home.

These changes to the lab structure were possible thanks, in part, to funding and support provided from the UCLA Center for the Advancement of Teaching. “That transition to students having ownership of the experiment is the kind of high-level learning experience that we seek for UCLA students, so we were happy to support that work,” said Adrienne Lavine, associate vice provost for the UCLA Center for the Advancement of Teaching and a professor of mechanical engineering.

For Lavine, the move to remote instruction has created an opportunity for faculty to reflect on their teaching and how that affects student learning. “I think there’s a lot of faculty out there who are doing an incredible job of being thoughtful in how to handle this, and they will learn lessons that can be taken back into in-person instruction,” she said.

This article originally appeared in the UCLA Newsroom.

A photo of Assistant Professor Wesley Campbell, UCLA Physics & Astronomy

UCLA physicists develop world’s best quantum bits

A photo of Assistant Professor Wesley Campbell, UCLA Physics & Astronomy

Assistant Professor Wesley Campbell, UCLA Physics & Astronomy (Photo Credit: UCLA)

A team of researchers at UCLA has set a new record for preparing and measuring the quantum bits, or qubits, inside of a quantum computer without error. The techniques they have developed make it easier to build quantum computers that outperform classical computers for important tasks, including the design of new materials and pharmaceuticals. The research is published in the peer-reviewed, online open-access journal, npj Quantum Information, published by Nature and including the exceptional research on quantum information and quantum computing.

Currently, the most powerful quantum computers are “noisy intermediate-scale quantum” (NISQ) devices and are very sensitive to errors. Error in preparation and measurement of qubits is particularly onerous: for 100 qubits, a 1% measurement error means a NISQ device will produce an incorrect answer about 63% of the time, said senior author Eric Hudson, a UCLA professor of physics and astronomy.

To address this major challenge, Hudson and UCLA colleagues recently developed a new qubit hosted in a laser-cooled, radioactive barium ion. This “goldilocks ion” has nearly ideal properties for realizing ultra-low error rate quantum devices, allowing the UCLA group to achieve a preparation and measurement error rate of about 0.03%, lower than any other quantum technology to date, said co-senior author Wesley Campbell, also a UCLA professor of physics and astronomy.

The development of this exciting new qubit at UCLA should impact almost every area of quantum information science, Hudson said. This radioactive ion has been identified as a promising system in quantum networking, sensing, timing, simulation and computation, and the researchers’ paper paves the way for large-scale NISQ devices.

Co-authors are lead author Justin Christensen, a postdoctoral scholar in Hudson’s laboratory, and David Hucul, a former postdoctoral scholar in Hudson and Campbell’s laboratories, who is now a physicist at the U.S. Air Force Research Laboratory.

The research is funded by the U.S. Army Research Office.

Campbell and Hudson are primary investigators of a major $2.7 million U.S. Department of Energy Quantum Information Science Research project to lay the foundation for the next generation of computing and information processing, as well as many other innovative technologies.

This article originally appeared on the UCLA Physical Sciences website.

Photos of UCLA College professors Jose Rodriguez and Erik Petigura.

Two UCLA College faculty members awarded 2020 Sloan Research Fellowships

Photos of UCLA College professors Jose Rodriguez and Erik Petigura.

UCLA College professors Jose Rodriguez (left) and Erik Petigura (right).

Two young UCLA College professors, and two others, are among 126 scientists and scholars from more than 60 colleges and universities in the United States and Canada selected today to receive 2020 Sloan Research Fellowships. UCLA is tied for fifth — behind only Stanford, UC Berkeley, UC San Diego and the Massachusetts Institute of Technology — in the number of faculty honored this year by the Alfred P. Sloan Foundation, which selects early-career scientists and scholars who are rising stars of science.

“To receive a Sloan Research Fellowship is to be told by your fellow scientists that you stand out among your peers,” says Adam F. Falk, president of the Alfred P. Sloan Foundation. “A Sloan Research Fellow is someone whose drive, creativity and insight make them a researcher to watch.”

Since the first Sloan Research Fellowships were awarded in 1955, 165 UCLA faculty members have received Sloan Research Fellowships. UCLA College’s 2020 recipients are:

Erik Petigura

Petigura, an assistant professor of physics and astronomy in the UCLA College, studies exoplanets — planets orbiting stars other than the sun — using ground-based and space-based telescopes. “My passion for exoplanets is motivated by a deceptively simple, yet fundamental question: Why are we here?” said Petigura. “Our species has wrestled with this question since antiquity, and it resonates strongly with me.” Exoplanets offer the key avenue toward answering this question, as they inform the otherwise elusive physical processes that led to the formation of the solar system, the formation of the Earth and the origin of life. His group has shown that nearly every sun-like star has a planet between the size of Earth and Neptune — sizes not present in the solar system. “In other words, our solar system is not a typical outcome of planet formation, at least in that one key respect,” he said. As a Sloan Fellow, Petigura plans to study the origin, evolution and fate of these ubiquitous planets.

Jose Rodriguez

Rodriguez, an assistant professor of chemistry and biochemistry in the UCLA College, develops and applies new scientific methods in bio-imaging to determine, and provide a deep scientific understanding of, cellular and molecular structures and reveal undiscovered structures that influence chemistry, biology and medicine. His research combines computational, biochemical and biophysical experiments. His laboratory is working to explore the structures adopted by prions — a form of infectious protein that causes neurodegenerative disorders. Prion proteins, like the amyloid proteins associated with Alzheimer’s disease, form large clumps that damage and ultimately kill neurons in the brain. Among his awards and honors, Rodriguez won a 2019 Packard fellowship for Science and Engineering by the David and Lucile Packard Foundation; a 2018 Pew scholar in the biomedical sciences, a 2017 Searle Scholar and a 2017 Beckman Young Investigator by the Arnold and Mabel Beckman Foundation.

Winners of Sloan Research Fellowships receive a two-year, $75,000 award to support their research. The fellowships are intended to enhance the careers of exceptional young scientists and scholars in chemistry, computer science, economics, mathematics, computational and evolutionary molecular biology, neuroscience, ocean sciences and physics. The Sloan Foundation, which is based in New York, was established in 1934.

This article originally appeared in the UCLA Newsroom.

Photo of orbits of the G objects at the center of our galaxy

Astronomers discover class of strange objects near our galaxy’s enormous black hole

Photo of orbits of the G objects at the center of our galaxy

Orbits of the G objects at the center of our galaxy, with the supermassive black hole indicated with a white cross. Stars, gas and dust are in the background. Photo: Anna Ciurlo, Tuan Do/UCLA Galactic Center Group

Astronomers from UCLA’s Galactic Center Orbits Initiative have discovered a new class of bizarre objects at the center of our galaxy, not far from the supermassive black hole called Sagittarius A*. They published their research in the Jan. 16 issue of the journal Nature.

“These objects look like gas and behave like stars,” said co-author Andrea Ghez, UCLA’s Lauren B. Leichtman and Arthur E. Levine Professor of Astrophysics and director of the UCLA Galactic Center Group.

The new objects look compact most of the time and stretch out when their orbits bring them closest to the black hole. Their orbits range from about 100 to 1,000 years, said lead author Anna Ciurlo, a UCLA postdoctoral researcher.

Ghez’s research group identified an unusual object at the center of our galaxy in 2005, which was later named G1. In 2012, astronomers in Germany made a puzzling discovery of a bizarre object named G2 in the center of the Milky Way that made a close approach to the supermassive black hole in 2014. Ghez and her research team believe that G2 is most likely two stars that had been orbiting the black hole in tandem and merged into an extremely large star, cloaked in unusually thick gas and dust.

“At the time of closest approach, G2 had a really strange signature,” Ghez said. “We had seen it before, but it didn’t look too peculiar until it got close to the black hole and became elongated, and much of its gas was torn apart. It went from being a pretty innocuous object when it was far from the black hole to one that was really stretched out and distorted at its closest approach and lost its outer shell, and now it’s getting more compact again.”

“One of the things that has gotten everyone excited about the G objects is that the stuff that gets pulled off of them by tidal forces as they sweep by the central black hole must inevitably fall into the black hole,” said co-author Mark Morris, UCLA professor of physics and astronomy. “When that happens, it might be able to produce an impressive fireworks show since the material eaten by the black hole will heat up and emit copious radiation before it disappears across the event horizon.”

But are G2 and G1 outliers, or are they part of a larger class of objects? In answer to that question, Ghez’s research group reports the existence of four more objects they are calling G3, G4, G5 and G6. The researchers have determined each of their orbits. While G1 and G2 have similar orbits, the four new objects have very different orbits.

Ghez believes all six objects were binary stars — a system of two stars orbiting each other — that merged because of the strong gravitational force of the supermassive black hole. The merging of two stars takes more than 1 million years to complete, Ghez said.

“Mergers of stars may be happening in the universe more often than we thought, and likely are quite common,” Ghez said. “Black holes may be driving binary stars to merge. It’s possible that many of the stars we’ve been watching and not understanding may be the end product of mergers that are calm now. We are learning how galaxies and black holes evolve. The way binary stars interact with each other and with the black hole is very different from how single stars interact with other single stars and with the black hole.”

Ciurlo noted that while the gas from G2’s outer shell got stretched dramatically, its dust inside the gas did not get stretched much. “Something must have kept it compact and enabled it to survive its encounter with the black hole,” Ciurlo said. “This is evidence for a stellar object inside G2.”

“The unique dataset that Professor Ghez’s group has gathered during more than 20 years is what allowed us to make this discovery,” Ciurlo said. “We now have a population of ‘G’ objects, so it is not a matter of explaining a ‘one-time event’ like G2.”

The researchers made observations from the W.M. Keck Observatory in Hawaii and used a powerful technology that Ghez helped pioneer, called adaptive optics, which corrects the distorting effects of the Earth’s atmosphere in real time. They conducted a new analysis of 13 years of their UCLA Galactic Center Orbits Initiative data.

In September 2019, Ghez’s team reported that the black hole is getting hungrier and it is unclear why. The stretching of G2 in 2014 appeared to pull off gas that may recently have been swallowed by the black hole, said co-author Tuan Do, a UCLA research scientist and deputy director of the Galactic Center Group. The mergers of stars could feed the black hole.

The team has already identified a few other candidates that may be part of this new class of objects, and are continuing to analyze them.

Ghez noted the center of the Milky Way galaxy is an extreme environment, unlike our less hectic corner of the universe.

“The Earth is in the suburbs compared to the center of the galaxy, which is some 26,000 light-years away,” Ghez said. “The center of our galaxy has a density of stars 1 billion times higher than our part of the galaxy. The gravitational pull is so much stronger. The magnetic fields are more extreme. The center of the galaxy is where extreme astrophysics occurs — the X-sports of astrophysics.”

Ghez said this research will help to teach us what is happening in the majority of galaxies.

Other co-authors include Randall Campbell, an astronomer with the W.M. Keck Observatory in Hawaii; Aurelien Hees, a former UCLA postdoctoral scholar, now a researcher at the Paris Observatory in France; and Smadar Naoz, a UCLA assistant professor of physics and astronomy.

The research is funded by the National Science Foundation, W.M. Keck Foundation and Keck Visiting Scholars Program, the Gordon and Betty Moore Foundation, the Heising-Simons Foundation, Lauren Leichtman and Arthur Levine, Jim and Lori Keir, and Howard and Astrid Preston.

In July 2019, Ghez’s research team reported on the most comprehensive test of Einstein’s iconic general theory of relativity near the black hole. They concluded that Einstein’s theory passed the test and is correct, at least for now.

► Watch a four-minute film about Ghez’s research

►View an animation below of the orbits of the G objects, together with the orbits of stars near the supermassive black hole. Credit: Advanced Visualization Lab, National Center for Supercomputing Applications, University of Illinois

This article originally appeared in the UCLA Newsroom.

UCLA leads development of first-of-its-kind telescope for gamma-ray astronomy

Researchers using the array will be able to study the gamma rays in the sky with the sensitivity 10 times better than currently achieved. This will help to address some of the most important and perplexing questions in very-high-energy astrophysics.

Space physicist wins Royal Astronomical Society 2019 Gold Medal

Margaret Kivelson, who discovered an ocean inside Jupiter’s moon Europa and a magnetic field generated by neighboring Ganymede, has been awarded the Royal Astronomical Society’s 2019 Gold Medal.

Technique for measuring and controlling electron state is a breakthrough in quantum computing

“The dream is to have an array of hundreds or thousands of qubits all working together to solve a difficult problem,” said graduate student Joshua Schoenfield. “This work is an important step toward realizing that dream.”

UCLA astronomers watch star clusters spewing out dust

Galaxies are often thought of as sparkling with stars, but they also contain gas and dust. Now, a team led by UCLA astronomers has used new data to show that stars are responsible for producing dust on galactic scales, a finding consistent with long-standing theory.

UCLA physicists discover ‘apparent departure from the laws of thermodynamics’

According to the basic laws of thermodynamics, if you leave a warm apple pie in a winter window eventually the pie would cool down to the same temperature as the surrounding air.