from the world's big
Cosmic death beams: Understanding gamma ray bursts
Gigantic explosions of light are reverberating across the universe.
Dr. Michelle Thaller is an astronomer who studies binary stars and the life cycles of stars. She is Assistant Director of Science Communication at NASA. She went to college at Harvard University, completed a post-doctoral research fellowship at the California Institute of Technology (Caltech) in Pasadena, Calif. then started working for the Jet Propulsion Laboratory's (JPL) Spitzer Space Telescope. After a hugely successful mission, she moved on to NASA's Goddard Space Flight Center (GSFC), in the Washington D.C. area. In her off-hours often puts on about 30lbs of Elizabethan garb and performs intricate Renaissance dances. For more information, visit NASA.
MICHELLE THALLER: Walter, you've asked a question about how explosions propagate through space. And of course, the amazing thing is that there are incredibly violent explosions going on all around us. I remember I spent one night at Mount Palomar. And there is a specific telescope up there it was called the Palomar Transient Factory that scans the sky for supernova explosions. And the amazing thing was that in a single night-- just one night being up on top of this mountain in Southern California they detected about 20 supernova explosions. And that's an entire solar system ripping itself apart. In a single night, you see 20 of them. And there are actually more violent explosions still, more energetic explosions called gamma ray bursts. And gamma ray bursts are almost sort of unbelievably violent. In a single flash of radiation, one little object can outshine literally the rest of the known universe, billions of galaxies. It becomes so bright that, quite honestly, we had a lot of trouble explaining where all that energy could possibly come from.
Now, a gamma ray burst, you think, wow, something outshines the entire universe, that must not happen very often. Well, incredibly, with our satellites, we detect about one a day. So all around us, there are these mind-blowingly violent events. By and large, they don't affect us much. And that's because of the distance. You see, the main amount of radiation that comes out of these is in the form of light. And I don't mean just visible light. Gamma ray bursts, as the name suggests, have a lot of gamma rays. Now, gamma rays are very high-energy form of light. And gamma rays are produced when conditions the gas around the object reach the many, many billions of degrees. When you're a billion degrees hot, you actually shine, naturally, in gamma rays. Things like supernova explosions, you get a lot of x-rays, things that are millions of degrees hot. But it's still light gamma rays, X-rays, ultraviolet light, the light that we see, visible light, and then there's lower-energy light, too, like microwaves and radio.
The amazing thing is that there's so many different kinds of light, and we are really blind almost all of them. We see a tiny little bit of light that's available. But life is made of photons, and light travels through space. But there's a wonderful thing called the inverse square law, and that describes how the intensity of light drops as you move farther and farther away. And really what it has to do with is the area of a sphere. If you have a light source, and light is coming away, say, from the sun. The sun is shining in all directions. There's a sphere of photons coming away from the light. As those photons move out into space, they're covering a larger and larger area as they move away. And the area of a sphere is related to the square of the distance away that you are from the object. So the square of the radius, the inverse square law. So if you move twice as far away from the sun as we are now, the light from the sun would drop by a factor of four. We've gone twice as far away, it's four times as faint. These objects are so far away from us that that light is spread over an incredibly large area, and it's really lost any sort of intensity it had. In fact, the challenge is really to detect them at all. All of the radiation that has actually arrived here at the surface of the Earth from space-- there are these giant explosions that are putting off very-high-energy radiation.
But that radiation is expanding out in a sphere, away from that source. By the time it gets here, it's so faint that every bit of energy we've ever collected is about the equivalent to a snowflake. It's very hard to even detect that high-energy radiation at such a great distance. Explosions are not very dramatic. And one of the things that kind of blows my mind is, a couple of years ago, one of our satellites picked up a gamma ray burst from a source about 7 billion light years away. And that means that the light has taken 7 billion years to travel to us. But that light, that explosion, happened before the sun even formed. And that explosion was so bright not just in gamma rays, there was also some visible light that we could see associated with it. And there was a tiny little burst of light you would have seen in the Southern Hemisphere. If you were looking at exactly the right part of the sky at the right time, you would have seen a tiny little faint star turn on and off. There was something that was visible to the naked eye that was 7 billion light years away. That's amazing. Think about the power of that explosion. And one of the things that we know is that if you were anywhere close to a gamma ray burst, things could get very bad, indeed. Supernova explosions don't really seem very violent in comparison.
Even if there are stars in the sky that are on the order of 10, 20, 50 light years away, if one of those went supernova, it would be a beautiful show, there'd be a really bright star in the sky for a while at night, probably bright enough to read by but the radiation wouldn't be damaging to us. It really would probably be hardly measurable. In the case of a gamma ray burst, however, if a gamma burst that violent of an explosion went off anywhere in our galaxy. And one of the things that we now know from observations of gamma ray bursts is that they appear to actually go off in beams. So there must be very intense magnetic fields during this event. And whatever is collapsing the star that's exploding, there's a magnetic pole, and radiation gets beamed up the magnetic poles. So the good news is that if you're not in the way of one of those beams, you're probably safe. So even if a gamma ray burst goes off fairly near to us but we're not in direct line of sight of one of those beams, we're OK. Of course what that means, that we have actually identified stars around the sky that may go gamma ray burst someday, very massive stars that will probably explode in extremely violent ways. One of them is Eta Carinae, in the south. But it looks like the pole of Eta Carinae is not pointing toward us.
There's another star, called Wolf-Rayet 104. And for a while, as we were observing the star, it looked like the pole of the star was actually pointed pretty close to us. But now we have better measurements and we actually think it's not very close. Now, all of these things are not really worth worrying about. But the truth is, we don't understand these very well at all. We don't know the exact angle of the beam. We don't know how wide it is or how narrow it is. So there's no guarantee that, someday, we won't be hit by a gamma ray burst. And the amazing thing, like I said, is we actually detect one of these once a day. But pretty much all of those are in very distant galaxies, galaxies that are really far away, millions or billions of light years away. And yes, we were in the way of the beam, and we saw the gamma rays, but it's so far away that radiation is very, very dispersed by the time it reaches us. So, explosions propagate in the form of light and as long as you're far enough away, the inverse-square law will actually drop down that radiation to a very, very low level. In the case of a beamed event, it may not follow the inverse-square law, because it's a beam of light coming right at you. But they're still very, very faint that far away, and we're safe.
- In a single night, astronomers are able to detect about 20 supernova explosions.
- Gamma ray bursts are even more energetic — in a single flash of radiation they can outshine the rest of the known universe.
- If a gamma burst went off anywhere in our galaxy, it could be disastrous. The radiation would be beamed far and wide. However, as long as you're not in the way of one of those beams — or very far the site of the initial explosion — then you're probably safe.
Higher education faces challenges that are unlike any other industry. What path will ASU, and universities like ASU, take in a post-COVID world?
- Everywhere you turn, the idea that coronavirus has brought on a "new normal" is present and true. But for higher education, COVID-19 exposes a long list of pernicious old problems more than it presents new problems.
- It was widely known, yet ignored, that digital instruction must be embraced. When combined with traditional, in-person teaching, it can enhance student learning outcomes at scale.
- COVID-19 has forced institutions to understand that far too many higher education outcomes are determined by a student's family income, and in the context of COVID-19 this means that lower-income students, first-generation students and students of color will be disproportionately afflicted.
What conditions of the new normal were already appreciated widely?<p>First, we understand that higher education is unique among industries. Some industries are governed by markets. Others are run by governments. Most operate under the influence of both markets and governments. And then there's higher education. Higher education as an "industry" involves public, private, and for-profit universities operating at small, medium, large, and now massive scales. Some higher education industry actors are intense specialists; others are adept generalists. Some are fantastically wealthy; others are tragically poor. Some are embedded in large cities; others are carefully situated near farms and frontiers.</p> <p>These differences demonstrate just some of the complexities that shape higher education. Still, we understand that change in the industry is underway, and we must be active in directing it. Yet because of higher education's unique (and sometimes vexing) operational and structural conditions, many of the lessons from change management and the science of industrial transformation are only applicable in limited or highly modified ways. For evidence of this, one can look at various perspectives, including those that we have offered, on such topics as <a href="https://www.insidehighered.com/digital-learning/blogs/rethinking-higher-education/lessons-disruption" target="_blank">disruption</a>, <a href="https://www.nytimes.com/2020/02/20/education/learning/education-technology.html" target="_blank">technology management</a>, and so-called "<a href="https://www.insidehighered.com/sites/default/server_files/media/Excerpt_IHESpecialReport_Growing-Role-of-Mergers-in-Higher-Ed.pdf" target="_blank">mergers and acquisitions</a>" in higher education. In each of these spaces, the "market forces" and "market rules" for higher education are different than they are in business, or even in government. This has always been the case and it is made more obvious by COVID-19.</p> <p>Second, with so much excitement about innovation in higher education, we sometimes lose sight of the fact that students are—and should remain—the core cause for innovation. Higher education's capacity to absorb new ideas is strong. But the ideas that endure are those designed to benefit students, and therefore society. This is important to remember because not all innovations are designed with students in mind. The recent history of innovation in higher education includes several cautionary tales of what can happen when institutional interests—or worse, <a href="https://www.insidehighered.com/news/2016/02/09/apollos-new-owners-seek-fresh-start-beleaguered-company" target="_blank">shareholder</a> interests—are placed above student well-being.</p>
Photo: Getty Images<p>Third, it is abundantly apparent that universities must leverage technology to increase educational quality and access. The rapid shift to delivering an education that complies with social distancing guidelines speaks volumes about the adaptability of higher education institutions, but this transition has also posed unique difficulties for colleges and universities that had been slow to adopt digital education. The last decade has shown that online education, implemented effectively, can meet or even surpass the quality of in-person <a href="https://link-springer-com.ezproxy1.lib.asu.edu/article/10.1007/s10639-019-10027-z" target="_blank">instruction</a>.</p><p>Digital instruction, broadly defined, leverages online capabilities and integrates adaptive learning methodologies, predictive analytics, and innovations in instructional design to enable increased student engagement, personalized learning experiences, and improved learning outcomes. The ability of these technologies to transcend geographic barriers and to shrink the marginal cost of educating additional students makes them essential for delivering education at scale.</p><p>As a bonus, and it is no small thing given that they are the core cause for innovation, students embrace and enjoy digital instruction. It is their preference to learn in a format that leverages technology. This should not be a surprise; it is now how we live in all facets of life.</p><p>Still, we have only barely begun to conceive of the impact digital education will have. For example, emerging virtual and augmented reality technologies that facilitate interactive, hands-on learning will transform the way that learners acquire and apply new knowledge. Technology-enabled learning cannot replace the traditional college experience or ensure the survival of any specific college, but it can enhance student learning outcomes at scale. This has always been the case, and it is made more obvious by COVID-19.</p>
What conditions of the new normal were emerging suspicions?<p>Our collective thinking about the role of institutional or university-to-university collaboration and networking has benefitted from a new clarity in light of COVID-19. We now recognize more than ever that colleges and universities must work together to ensure that the American higher education system is resilient and sufficiently robust to meet the needs of students and their families.</p> <p>In recent weeks, various commentators have suggested that higher education will face a wave of institutional <a href="https://www.businessinsider.com/scott-galloway-predicts-colleges-will-close-due-to-pandemic-2020-5" target="_blank">closures</a> and consolidations and that large institutions with significant online instruction capacity will become dominant.</p> <p>While ASU is the largest public university in the United States by enrollment and among the most well-equipped in online education, we strongly oppose "let them fail" mindsets. The strength of American higher education relies on its institutional diversity, and on the ability of colleges and universities to meet the needs of their local communities and educate local students. The needs of learners are highly individualized, demanding a wide range of options to accommodate the aspirations and learning styles of every kind of student. Education will become less relevant and meaningful to students, and less responsive to local needs, if institutions of higher learning are allowed to fail. </p> <p>Preventing this outcome demands that colleges and universities work together to establish greater capacity for remote, distributed education. This will help institutions with fewer resources adapt to our new normal and continue to fulfill their mission of serving students, their families, and their communities. Many had suspected that collaboration and networking were preferable over letting vulnerable colleges fail. COVID-19's new normal seems to be confirming this.</p>
President Barack Obama delivers the commencement address during the Arizona State University graduation ceremony at Sun Devil Stadium May 13, 2009 in Tempe, Arizona. Over 65,000 people attended the graduation.
Photo by Joshua Lott/Getty Images<p>A second condition of the new normal that many had suspected to be true in recent years is the limited role that any one university or type of university can play as an exemplar to universities more broadly. For decades, the evolution of higher education has been shaped by the widespread imitation of a small number of elite universities. Most public research universities could benefit from replicating Berkeley or Michigan. Most small private colleges did well by replicating Williams or Swarthmore. And all universities paid close attention to Harvard, Princeton, MIT, Stanford, and Yale. It is not an exaggeration to say that the logic of replication has guided the evolution of higher education for centuries, both in the US and abroad.</p><p>Only recently have we been able to move beyond replication to new strategies of change, and COVID-19 has confirmed the legitimacy of doing so. For example, cases such as <a href="https://www.washingtonpost.com/education/2020/03/10/harvard-moves-classes-online-advises-students-stay-home-after-spring-break-response-covid-19/" target="_blank">Harvard's</a> eviction of students over the course of less than one week or <a href="https://www.nhregister.com/news/coronavirus/article/Mayor-New-Haven-asks-for-coronavirus-help-Yale-15162606.php" target="_blank">Yale's apparent reluctance</a> to work with the city of New Haven, highlight that even higher education's legacy gold standards have limits and weaknesses. We are hopeful that the new normal will include a more active and earnest recognition that we need many types of universities. We think the new normal invites us to rethink the very nature of "gold standards" for higher education.</p>
A graduate student protests MIT's rejection of some evacuation exemption requests.
Photo: Maddie Meyer/Getty Images<p>Finally, and perhaps most importantly, we had started to suspect and now understand that America's colleges and universities are among the many institutions of democracy and civil society that are, by their very design, incapable of being sufficiently responsive to the full spectrum of modern challenges and opportunities they face. Far too many higher education outcomes are determined by a student's family income, and in the context of COVID-19 this means that lower-income students, first-generation students and students of color will be disproportionately afflicted. And without new designs, we can expect postsecondary success for these same students to be as elusive in the new normal, as it was in the <a href="http://pellinstitute.org/indicators/reports_2019.shtml" target="_blank">old normal</a>. This is not just because some universities fail to sufficiently recognize and engage the promise of diversity, this is because few universities have been designed from the outset to effectively serve the unique needs of lower-income students, first-generation students and students of color.</p>
Where can the new normal take us?<p>As colleges and universities face the difficult realities of adapting to COVID-19, they also face an opportunity to rethink their operations and designs in order to respond to social needs with greater agility, adopt technology that enables education to be delivered at scale, and collaborate with each other in order to maintain the dynamism and resilience of the American higher education system.</p> <p>COVID-19 raises questions about the relevance, the quality, and the accessibility of higher education—and these are the same challenges higher education has been grappling with for years. </p> <p>ASU has been able to rapidly adapt to the present circumstances because we have spent nearly two decades not just anticipating but <em>driving</em> innovation in higher education. We have adopted a <a href="https://www.asu.edu/about/charter-mission-and-values" target="_blank">charter</a> that formalizes our definition of success in terms of "who we include and how they succeed" rather than "<a href="https://www.washingtonpost.com/opinions/2019/10/17/forget-varsity-blues-madness-lets-talk-about-students-who-cant-afford-college/" target="_blank">who we exclude</a>." We adopted an entrepreneurial <a href="https://president.asu.edu/read/higher-logic" target="_blank">operating model</a> that moves at the speed of technological and social change. We have launched initiatives such as <a href="https://www.instride.com/how-it-works/" target="_blank">InStride</a>, a platform for delivering continuing education to learners already in the workforce. We developed our own robust technological capabilities in ASU <a href="https://edplus.asu.edu/" target="_blank">EdPlus</a>, a hub for research and development in digital learning that, even before the current crisis, allowed us to serve more than 45,000 fully online students. We have also created partnerships with other forward-thinking institutions in order to mutually strengthen our capabilities for educational accessibility and quality; this includes our role in co-founding the <a href="https://theuia.org/" target="_blank">University Innovation Alliance</a>, a consortium of 11 public research universities that share data and resources to serve students at scale. </p> <p>For ASU, and universities like ASU, the "new normal" of a post-COVID world looks surprisingly like the world we already knew was necessary. Our record breaking summer 2020 <a href="https://asunow.asu.edu/20200519-sun-devil-life-summer-enrollment-sets-asu-record" target="_blank">enrollment</a> speaks to this. What COVID demonstrates is that we were already headed in the right direction and necessitates that we continue forward with new intensity and, we hope, with more partners. In fact, rather than "new normal" we might just say, it's "go time." </p>
Hollywood has created an idea of aliens that doesn't match the science.
- Ask someone what they think aliens look like and you'll probably get a description heavily informed by films and pop culture. The existence of life beyond our planet has yet to be confirmed, but there are clues as to the biology of extraterrestrials in science.
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- In this compilation, Wilson, theoretical physicist Michio Kaku, Bill Nye, and evolutionary biologist Jonathan B. Losos explain why aliens don't look like us and why Hollywood depictions are mostly inaccurate.
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- The company donates a portion of profits to charity every month.
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