An artistic take on primordial black holes. Credit: NASA’s Goddard Space Flight Center
Small primordial black holes (PBHs) are one of the hot topics in astronomy and cosmology today. These hypothetical black holes are believed to have formed soon after the Big Bang, resulting from pockets of subatomic matter so dense that they underwent gravitational collapse. At present, PBHs are considered a candidate for dark matter, a possible source of primordial gravitational waves, and a resolution to various problems in physics. However, no definitive PBH candidate has been observed so far, leading to proposals for how we may find these miniature black holes.
Recent research has suggested that main-sequence neutron and dwarf stars might contain small PBHs in their interiors that are slowly consuming their gas supply. In a recent study, a team of physicists extended this idea to include a new avenue for potentially detecting PBHs. Basically, we could search inside objects like planets and asteroids or employ large plates or slabs of metal to detect PBHs for signs of their passage. By detecting the microchannels these bodies would leave, scientists could finally confirm the existence of PBHs and shed light on some of the greatest mysteries in cosmology today.
Since the beginning of the Digital Age (ca. the 1970s), theoretical physicists have speculated about the possible connection between information and the physical Universe. Considering that all matter is made up of information that describes the state of a quantum system (aka. quantum information), and genetic information is coded in our DNA, it’s not farfetched at all to think that physical reality can be expressed in terms of data.
This has led to many thought experiments and paradoxes, where researchers have attempted to estimate the information capacity of the cosmos. In a recent study, Dr. Melvin M. Vopson – a Mathematician and Senior Lecturer at Portsmouth University – offered new estimates of how much information is encoded in all the baryonic matter (aka. ordinary or “luminous” matter) in the Universe.
This image shows two massive black holes in the OJ 287 galaxy. The smaller black hole orbits the larger one, which is also surrounded by a disk of gas. When the smaller black hole crashes through the disk, it produces a flare brighter than 1 trillion stars. Credit: NASA/JPL-Caltech
NASA’s Spitzer Space Telescope may be retired, but the things it witnessed during its sixteen and a half year mission will be the subject of study for many years to come. For instance, Spitzer is the only telescope to witness something truly astounding occurring at the center of the distant galaxy OJ 287: a supermassive black hole (SMBH) orbited by another black hole that regularly passes through its accretion disk.
Whenever this happens, it causes a flash that is brighter than all the stars in the Milky Way combined. Using Spitzer‘s observations, an international team of astronomers was able to finally create a model that accurately predicts the timing of these flashes and the orbit of the smaller black hole. In addition to demonstrating General Relativity in action, their findings also provide validation to Stephen Hawking‘s “no-hair theorem.”
In honor of Dr. Stephen Hawking, the COSMOS center will be creating the most detailed 3D mapping effort of the Universe to date. Credit: BBC, Illus.: T.Reyes
Stephen Hawking is rightly seen as one of the most influential scientists of our time. In his time on this planet, the famed physicist, science communicator, author and luminary became a household name, synonymous with the likes of Einstein, Newton and Galileo. What is even more impressive is the fact that he managed to maintain his commitment to science, education and humanitarian efforts despite suffering from a slow, degenerative disease.
Even though Hawking recently passed away, his influence is still being felt. Shortly before his death, Hawking submitted a paper offering his final theory on the origins of the Universe. The paper, which was published earlier this week (on Wednesday, May 2nd), offers a new take on the Big Bang Theory that could revolutionize the way we think of the Universe, how it was created, and how it evolved.
The paper, titled “A smooth exit from eternal inflation?“, was published in the Journal of High Energy Physics. The theory was first announced at a conference at the University of Cambridge in July of last year, where Professor Thomas Hertog (a Belgian physicist at KU Leuven University) shared Hawking’s paper (which Hertog co-authored) on the occasion of his 75th birthday.
Stephen Hawking’s final theory on the Big Bang, submitted shortly before he passed away, was recently published. Credit: University of Cambridge
According to the current scientific consensus, all of the current and past matter in the Universe came into existence at the same time – roughly 13.8 billion years ago. At this time, all matter was compacted into a very small ball with infinite density and intense heat. Suddenly, this ball started to inflate at an exponential rate, and the Universe as we know it began.
However, it is widely believed that since this inflation started, quantum effects will keep it going forever in some regions of the Universe. This means that globally, the Universe’s inflation is eternal. In this respect, the observable part of our Universe (measuring 13.8 billion light-years in any direction) is just a region in which inflation has ended and stars and galaxies formed.
“The usual theory of eternal inflation predicts that globally our universe is like an infinite fractal, with a mosaic of different pocket universes, separated by an inflating ocean. The local laws of physics and chemistry can differ from one pocket universe to another, which together would form a multiverse. But I have never been a fan of the multiverse. If the scale of different universes in the multiverse is large or infinite the theory can’t be tested. ”
In their new paper, Hawking and Hertog offer a new theory that predicts that the Universe is not an infinite fractal-like multiverse, but is finite and reasonably smooth. In short, they theorize that the eternal inflation, as part of the theory of the Big Bang, is wrong. As Hertog explained:
“The problem with the usual account of eternal inflation is that it assumes an existing background universe that evolves according to Einstein’s theory of general relativity and treats the quantum effects as small fluctuations around this. However, the dynamics of eternal inflation wipes out the separation between classical and quantum physics. As a consequence, Einstein’s theory breaks down in eternal inflation.”
In contrast to this, Hawking and Hertog offer an explanation based on String Theory, a branch of theoretical physics that attempts to unify General Relativity with quantum physics. This theory was proposed to explain how gravity interacts with the three other fundamental forces of the Universe (weak and strong nuclear forces and electromagnetism), thus producing a Theory of Everything (ToE).
To put it simply, this theory describes the fundamental constituents of the Universe as tiny, one-dimensional vibrating strings. Hawking and Hertog’s approach uses the holography concept of string theory, which postulates that the Universe is a large and complex hologram. In this theory, physical reality in certain 3D spaces can be mathematically reduced to 2D projections on a surface.
This illustration shows the evolution of the Universe, from the Big Bang on the left, to modern times on the right. Image: NASA
Together, Hawking and Hertog developed a variation of this concept to project out the dimension of time in eternal inflation. This enabled them to describe eternal inflation without having to rely on General Relativity, thus reducing inflation to a timeless state defined on a spatial surface at the beginning of time. In this respect, the new theory represents a change from Hawking’s earlier work on “no boundary theory”.
Also known as the Hartle and Hawking No Bounary Proposal, this theory viewed the Universe like a quantum particle – assigning it a wave function that described all possible Universes. This theory also predicted that if you go back in time to the beginning of the Universe, it would shrink and close off like a sphere. Lastly, it predicted that the Universe would eventually stop expanding and collapse in on itself.
As Hertog explains, this new theory is a departure from that earlier work:
“When we trace the evolution of our universe backwards in time, at some point we arrive at the threshold of eternal inflation, where our familiar notion of time ceases to have any meaning. Now we’re saying that there is a boundary in our past.”
Using this theory, Hawking and Hertog were able to derive more reliable predictions about the global structure of the Universe. In addition, a Universe predicted to emerge from eternal inflation on the past boundary is also finite and much simpler. Last, but not least, the theory is more predictive and testable than the infinite Multiverse predicted by the old theory of eternal inflation.
Artist’s impression of merging binary black holes. Credit: LIGO/A. Simonnet.
“We are not down to a single, unique universe, but our findings imply a significant reduction of the multiverse, to a much smaller range of possible universes,” said Hawking. In theory, a finite and smooth Universe is one we can observe (at least locally) and will be governed by physical laws that we are already familiar with. Compared to an infinite number of Universes governed by different physical laws, it certainly simplifies the math!
Looking ahead, Hertog plans to study the implications of this theory on smaller scales using data obtained by space telescopes about the local Universe. In addition, he hopes to take advantage of recent studies concerning gravitational waves (GWs) and the many events that have been detected. Essentially, Hertog believes that primordial GWs generated at the exit from eternal inflation are the most promising means to test the model.
Due to the expansion of our Universe since the Big Bang, these GWs would have very long wavelengths, ones which are outside the normal range of the Laser Interferometry Gravitational-Wave Observatory‘s (LIGO) or Virgo‘s detectors. However, the Laser Interferometry Space Antenna (LISA) – an ESA-led plan for a space-based gravitational wave observatory – and other future experiments may be capable of measuring them.
Even though he is longer with us, Hawking’s final theory could be his profound contribution to science. If future research should prove him correct, then Hawking will have resolved one of the most daunting problems in modern astrophysics and cosmology. Just one more achievement from a man who spent his life changing how people think about the Universe!
Hawking has experienced zero gravity before, when he flew on Zero Gravity Corp's modified Boeing 727 in 2007. Image: By Jim Campbell/Aero-News Network
Dr. Stephen Hawking, the famed British theoretical physicist, science communicator, author and luminary, passed away in the early hours on Wednesday, March 14th. According to a statement from his family, the renowned scientist died peacefully in his home at Cambridge. He was 76 years old, and is survived by his first wife, Jane Wilde, and their three children – Lucy, Robert and Tim.
Dr. Hawking spent the past 50 years living with a terminal illness that slowly deprived him of his speech and the use of much of his body. He also leaves behind an unparalleled scientific legacy and millions of people worldwide who admired him for his genius, his sense of humor, and the way he sought to educate people on the importance of scientific research, space exploration, and disability awareness.
In 1963, when he was just 21 years old, Dr. Hawking was diagnosed with Amyotrophic Lateral Sclerosis (ALS, aka. Lou Gehrig’s disease), a degenerative form of motor neurone disease that would be with him for the rest of his life. At the time, he was told that he had only two years to live. This diagnosis caused Dr. Hawking to fall into a depression and lose interest in his studies, which he was pursuing at Cambridge University at the time.
Stephen Hawking and Jane Wilde on their wedding day, July 14th, 1966. Credit: telegraph.co.uk
However, his outlook soon changed as the disease progressed slower than his doctor’s originally though. It was also around this time that Hawking met his first wife, Jane Wilde. The two became engaged in October of 1964 and married on July 14th, 1966. Hawking would later say that his relationship with Wilde gave him “something to live for”.
The slow progression of the disease also allowed Dr. Hawking to embark on a career marked by brilliance, brashness, and original thinking. Among his many achievements, Dr. Hawing was the Lucasian Professor of Mathematics at the University of Cambridge, the Founder of the Center for Theoretical Cosmology, and served as the Sally Tsui Wong-Avery Director of Research at the Department of Applied Mathematics and Theoretical Physics until his passing.
During his lifetime, Dr. Hawking made invaluable contributions to the fields of theoretical physics and cosmology. These include his extensive work on gravitational singularity theorems (in collaboration with Roger Penrose), the theory that black holes emit radiation (often called Hawking Radiation), and a theory of cosmology that attempted to unify general relativity and quantum mechanics (aka. Theory of Everything).
OPeter Higgs and Stephen Hawking visiting the “Collider” exhibition at London’s Science Museum (Image: c. Science Museum 2013)
His many accolades, honors and awards included being made an Honorary Fellow of the Royal Society of Arts (FRSA), a lifetime member of the Pontifical Academy of Sciences, and a recipient of the Presidential Medal of Freedom – the highest civilian award in the United States. In 2002, Hawking was ranked number 25 in the BBC’s poll of the 100 Greatest Britons.
President Barack Obama talks with Stephen Hawking in the Blue Room of the White House before a ceremony presenting him and 15 others the Presidential Medal of Freedom, August 12, 2009. (Official White House photo by Pete Souza)
In a statement by his three children, Lucy, Robert and Tim praised their father’s courage and persistence and honored how his genius and sense of humor inspired people all across the world:
“We are deeply saddened that our beloved father passed away today. He was a great scientist and an extraordinary man whose work and legacy will live on for many years… He once said, ‘It would not be much of a universe if it wasn’t home to the people you love.’ We will miss him forever.”
News of his passing was also met with a flurry of condolences by friends, colleagues, fans, and people whose lives he touched over the years. NASA tweeted the following early this morning, followed by a video of Dr. Hawking addressing the astronauts of the ISS in 2014:
Famed scientists and science communicator Neil DeGrasse Tyson also expressed his condolences, tweeting:
His passing has left an intellectual vacuum in his wake. But it's not empty. Think of it as a kind of vacuum energy permeating the fabric of spacetime that defies measure. Stephen Hawking, RIP 1942-2018. pic.twitter.com/nAanMySqkt
The cast of the Big Bang Theory, one of the many hit TV shows that Dr. Hawking made several appearances on, also offered their condolences and admiration:
The @mndassoc is saddened to learn the death of Professor Stephen Hawking, Patron since 2008.
Our thoughts are with Professor Hawking’s family. Throughout his inspirational life Professor Hawking played a vital role in raising awareness of motor neurone disease around the world.
Despite having lived for five decades with this degenerative disease, Hawking had a very practical and courageous attitude about life. In 2011, he said in an interview with The Guardian that death was never far from his mind. “I have lived with the prospect of an early death for the last 49 years,” he said. “I’m not afraid of death, but I’m in no hurry to die. I have so much I want to do first.”
Hawking, a well-known atheist, was also clear on his thoughts on an afterlife. “I regard the brain as a computer which will stop working when its components fail,” he said. “There is no heaven or afterlife for broken down computers; that is a fairy story for people afraid of the dark.”
Dr. Hawking’s life and his contributions to science have been commemorated in many ways over the years. A film version of A Brief History of Time, directed by Errol Morris and produced by Steven Spielberg, premiered in 1992. In 1997, a six-part television series Stephen Hawking’s Universe premiered on PBS, with a companion book also being released. In 2014, the story of his diagnosis and the impact it had on his young family was showcased in the Oscar-winning film The Theory of Everything.
Stephen Hawking is a major proponent for colonizing other worlds, mainly to ensure humanity does not go extinct. Credit: educatinghumanity.com
Dr. Hawking has also been a major role model for people dealing with disabilities and degenerative illnesses and played an unparalleled role when it came to disability awareness and outreach. In 1999, he and eleven other luminaries joined with Rehabilitation International , an organization founded in 1922 “To advance the rights and inclusion of persons with disabilities across the world.”
In 2000, Dr. Hawking and his fellow luminaries signed the Charter for the Third Millennium on Disability, which called on governments around the world to prevent disabilities and protect disability rights. Throughout his life, Dr. Hawking also remained a committed educator – personally supervising 39 successful PhD students – and lending his voice to scientific and humanitarian goals.
These include Breakthrough Initiatives, an effort to search for extraterrestrial intelligence (SETI) in the Universe, which Dr. Hawking helped launch in 2015. That same year, he also used his influence and celebrity status to promote the The Global Goals, a series of 17 goals adopted by the United Nations Sustainable Development Summit to end extreme poverty, social inequality, and fixing climate change over the course of the next 15 years.
To commemorate his life and legacy, a book of condolence has been opened at Gonville and Caius College in Cambridge, where Prof Hawking was a fellow. All around the world, there are outpourings of remembrance and support for his family from people who are mourning Dr. Hawking’s passing and celebrating his life and achievements.
As Neil DeGrasse Tyson said, the death of Dr. Hawking has left a vacuum in the scientific community, and in the hearts of people everywhere. However, his life and his many contributions shall be remembered for a long time to come!
The VMS Eve (Virgin Mother Ship) carrys VSS Unity (Virgin Spaceship) for its first flight ever over Mojave, CA on Thursday September 8, 2016. Image: Virgin Galactic
Stephen Hawking has spent decades theorizing about the Universe. His thinking on black holes, quantum gravity, quantum mechanics, and a long list of other topics, has helped shape our understanding of the cosmos. Now it looks like the man who has spent most of his adult life bound to a wheel-chair will travel to the edge of space.
In an interview with Good Morning Britain, Hawking said “Richard Branson has offered me a seat on Virgin Galactic, and I said yes immediately.” Hawking added that his “three children have brought me great joy—and I can tell you what will make me happy, to travel in space.”
Stephen Hawking is one of the premier physicists and theorists of our time. Here he is being presented by his daughter Lucy Hawking at the lecture he gave for NASA’s 50th anniversary. Credit: NASA/Paul Alers
It’s all thanks to Richard Branson and his VSS Unity spaceship, which is still under development by The Spaceship Company. The Unity is designed to launch not from a rocket pad, but from underneath a carrier aircraft. By eliminating enormously expensive rocket launches from the whole endeavour, Branson hopes to make space more accessible to more people.
Virgin Spaceship Unity (VSS Unity) glides for the first time after being released from Virgin Mothership Eve (VMS Eve) over the Mojave Desert on 3rd, December 2016. Image: Virgin Galactic
The Virgin Galactic spacecraft is carried to an altitude of about 50,000 feet, then released from its carrier aircraft. Its rocket fires for about 1 minute, which accelerates the craft to three-and-a-half times the speed of sound, then is shut off. Then, according to Virgin Galactic, passengers will experience a “dramatic transition to silence and to true weightlessness.”
As the video shows, the spacecraft is still in glide testing phase, where it is carried to altitude, then released. There is no rocket burn, and the craft glides down and lands at its base.
This spaceflight won’t be Hawking’s first experience with weightlessness, however. To celebrate his 65th birthday, Hawking travelled on board Zero Gravity Corp’s modified Boeing 727 in 2007. At the time, that zero-g flight was in preparation for a trip into sub-orbital space with Virgin Galactic in 2009. But the development of Virgin Galactic’s spacecraft has suffered setbacks, and the 2009 date was not attainable.
Hawking has experienced zero gravity before, when he flew on Zero Gravity Corp’s modified Boeing 727 in 2007. Image: By Jim Campbell/Aero-News Network – http://www.flickr.com/photos/39735679@N00/475109138/ / http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=31873, Public Domain, https://commons.wikimedia.org/w/index.php?curid=3655144
Virgin Galactic’s stated aim is to “democratize space,” albeit at a cost of US $250,000 per person. But somehow I doubt that Hawking will be paying. If anyone has earned a free trip into space, it is Dr. Stephen Hawking.
Stephen Hawking recently issued some more dire warnings for humanity, saying that we have 1000 years to find a new planet. Credit: Public Domain/photo by Alexandar Vujadinovic
It has been argued that the greatest reason our species should explore space and colonize other planets is so that a cataclysmic fate won’t be able to claim all of humanity. That is the driving force behind Elon Musk’s plan to colonize Mars. And it has certainly been the driving point behind Stephen Hawking’s belief that humanity should become an interplanetary-species.
And according to Hawking, becoming interplanetary is something of a time-sensitive issue. During a recent speech presented at the Oxford Union Society (Oxford University’s prestigious debating society) Hawking laid it out plainly for the audience. Humanity has 1000 years to locate and colonize new planets, he claimed, or we will likely go extinct.
For almost 200 years, the Oxford Union Society has been a forum for intellectual debate. In the past, it has also hosted such speakers as the Dalai Lama, Stephen Fry, Morgan Freeman, Richard Dawkins, and Buzz Aldrin. On this occasion, Hawking addressed a crowd of students and professors about space exploration and humanity’s future – two subjects he’s well versed in!
Stephen Hawking is a major proponent for colonizing other worlds, mainly to ensure humanity does not go extinct. Credit: educatinghumanity.com
As Hawking made clear, humanity faces a number of existential threats, many of which are going to become a serious problem during the 21 century century. These include, but are not limited to, the threat of Climate Change, nuclear holocaust, terrorism, and the rise of artificial intelligence. The solution, Hawking argued, is to get into space and establish colonies as soon as possible.
As he was quoted as saying by the Christian Science Monitor, this will need to take place within the next 1000 years:
“Although the chance of a disaster to planet Earth in a given year may be quite low, it adds up over time, and becomes a near certainty in the next 1,000 or 10,000 years. By that time we should have spread out into space, and to other stars, so a disaster on Earth would not mean the end of the human race.”
This was not the first time Hawking has expressed concerns about the future. In January of 2015, Hawking joined Elon Musk and many other AI experts to pen the “Research Priorities for Robust and Beneficial Artificial Intelligence” – aka. the “Open Letter on Artificial Intelligence”. In this letter, he and the other signatories raised concerns about the short-term and long-term implications of AI, and urged that steps be taken to address them.
President Barack Obama talks with Stephen Hawking in the Blue Room of the White House before a ceremony presenting him and 15 others the Presidential Medal of Freedom on August 12th, 2009. Credit: whitehouse.gov/Pete Souza
In addition, back in January of 2016, Hawking warned that humanity’s technological progress has the power to outstrip us. This occurred during his speech at the 2016 Leith Lectures, where Hawking spoke about black holes and why they are fascinating. During the Q&A period that followed, Hawking turned to the much more dour subject of whether or not humanity has a future. As he said at the time:
“We face a number of threats to our survival, from nuclear war, catastrophic global warming, and genetically engineered viruses. The number is likely to increase in the future, with the development of new technologies, and new ways things can go wrong. However, we will not establish self-sustaining colonies in space for at least the next hundred years, so we have to be very careful in this period. Most of the threats we face come from the progress we have made in science and technology. We are not going to stop making progress, or reverse it, so we have to recognize the dangers and control them. I am an optimist, and I believe we can.”
Similarly, Hawking indicated back in 2010 that humanity’s survival beyond the next century would require that we become a space-faring race. In an interview with Big Think, Hawking claimed the odds of humanity making it to the 22nd century was bad enough for a single-planet species, let alone the 31st:
“I believe that the long-term future of the human race must be in space. It will be difficult enough to avoid disaster on planet Earth in the next hundred years, let alone the next thousand, or million. The human race shouldn’t have all its eggs in one basket, or on one planet. Let’s hope we can avoid dropping the basket until we have spread the load.”
Hawking has repeatedly advocated space exploration and colonization as a way of ensuring humanity’s survival. Credit: NASA/MSFC
But before anyone gets all gloomy, it should be noted that between our plans to colonize Mars, and the success of the Kepler mission, we have found hundreds of planets that could serve as potential homes for humanity. But as Hawking has stated in the past, we will need at least 100 years to develop all the necessary technologies to build colonies on even the closest of these planets (Mars).
Beyond our survival as a species, Professor Hawking also advocates space travel as a way of improving humanity’s understanding of itself. This was made evident in a direct quote that the Union live-tweeted during the speech, in which he said: “We must continue exploring space in order to improve our knowledge of humanity. We must go beyond our humble planet.”
And as he has done so often before, Hawking ended his speech on an optimistic note. According to the Independent, he wrapped up his Oxford lecture with the following words of advice:
“Remember to look up at the stars and not down at your feet. Try to make sense of what you see, wonder about what makes the universe exist. Be curious. However difficult life may seem, there is always something you can do and succeed at. It matters that you don’t just give up.”
It seems we have our work cut out for us. Extra-terrestrial and/or extra-solar colonies by 3016… or bust!
Artist's impression of a directed-energy propulsion laser sail in action. Credit: Q. Zhang/deepspace.ucsb.edu
Back in April, Russian billionaire Yuri Milner and famed cosmologist Stephen Hawking unveiled Project Starshot. As the latest venture by Breakthrough Initiatives, Starshot was conceived with the aims of sending a tiny spacecraft to the neighboring star system Alpha Centauri in the coming decades.
Relying on a sail that would be driven up to relativistic speeds by lasers, this craft would theoretically be capable of making the journey is just 20 years. Naturally, this project has attracted its fair share of detractors. While the idea of sending a star ship to another star system in our lifetime is certainly appealing, it presents numerous challenges.
Not one to shy away from any potential problems, Breakthrough Starshot has begun funding the necessary research to make sure that their concept will work. The results of their first research effort appeared recently in arXiv, in a study titled “The interaction of relativistic spacecrafts with the interstellar medium“.
Project Starshot, an initiative sponsored by the Breakthrough Foundation, is intended to be humanity’s first interstellar voyage. Credit: breakthroughinitiatives.org
Assessing the risks of interstellar travel, this paper addresses the greatest threat where relativistic speed is concerned: catastrophic collisions! To put it mildly, space is not exactly an empty medium (despite what the name might suggest). In truth, there are a lot of things out there on the “stellar highway” that can cause a fatal crash.
For instance, within interstellar space, there are clouds of dust particles and even stray atoms of gas that are the result of stellar formations and other processes. Any spacecraft traveling at 20% the speed of light (0.2 c) could easily be damaged or destroyed if it suffered a collision with even the tiniest of this particulate matter.
The research team was led by Dr. Chi Thiem Hoang, a postdoctoral fellow at Canadian Institute for Theoretical Astrophysics (CITA) at the University of Toronto. As Dr. Hoang told Universe Today via email:
“To evaluate the risks, we calculated the energy that each interstellar atom or dust grain transfers to the ship along the path of the projectile in the ship. This acquired energy rapidly heats a spot on the ship surface to high temperature, resulting in damage by reducing the material strength, melting or evaporation.”
The layout of the solar system, including the Oort Cloud, on a logarithmic scale. Credit: NASA
In short, the danger of a collision comes not from the physical impact, but from the energy that is generated due to the fact that the spaceship is traveling so fast. However, what they found was that while collisions with tiny dust grains are very likely, collisions with heavier atoms that can do the most damage would be more rare.
Nevertheless, the damage from so many tiny collisions will certainly add up over time. And it would only take one collision with a larger particle to end the mission. As Dr. Hoang explained:
“We found that the ship would be damaged by collision with heavy atoms and dust grains in the interstellar medium. Heavy atoms, mostly iron can damage the surface to a depth of 0.1mm. More importantly, the surface of the ship is eroded gradually by dust grains, to a depth of about 1mm. The ship may be completely destroyed if encountering a very big dust grain larger than 15micron, although it is extremely rare.”
In terms of damage, what they determined was that each iron atom can produce a damage track of 5 nanometer across, whereas a typical dust silicate grain measuring just 0.1. micron across (and containing about one billion iron atoms) could produce a large crater on the ship’s surface.
A phased laser array, perhaps in the high desert of Chile, propels sails on their journey. Credit: Breakthrough Initiatives.
Over time, the cumulative effect of this damage would pose a major risk for the ship’s survival. As a result, Dr. Hoang and his team recommended that some shielding would need to be mounted on the ship, and that it wouldn’t hurt to “clear the road” a little as well.
“We recommended to protect the ship by putting a shield of about 1 mm thickness made of strong, high melting temperature material like graphite.” he said. “We also suggested to destroy interstellar dust by using part of energy from laser sources.”
These projects, which are being funded by NASA, seek to harness the technology behind directed-energy propulsion to rapidly send missions to Mars and other locations within the Solar System in the future. Long-term applications include interstellar missions, similar to Starshot.
Artist’s impression of the Earth-like exoplanet discovered orbiting Alpha Centauri B iby the European Southern Observatory on October 17, 2012. Credit: ES
Other interesting projects overseen by Lubin and the UCSB lab include the Directed Energy System for Targeting of Asteroids and exploRation (DE-STAR). This system calls for the use of lasers to deflect asteroids, comets, and other near-Earth objects (NEO) that pose a credible risk of impact.
In all cases, directed-energy technology is being proposed as the solution to the problems posed by space travel. In the case of Starshot, these include (but are not limited to) inefficiency, mass, and/or the limited speeds of conventional rockets and ion engines.
As Professor Lubin told Universe Today via email, he and his colleagues are in general agreement with the research team and their findings:
“The recent paper by Hoang et al revisits the section (7) in our paper “A Roadmap to Interstellar Flight” that discusses our calculation for the effects of the ISM on the wafer scale spacecraft. Their general conclusion on the effects of the gas and dust collisions were essentially the same as ours, namely that it is an issue, but not a fatal one, if one uses the spacecraft geometry we recommend in our paper, namely orient the spacecraft edge on (like a Frisbee in flight) and then use an edge coating (we use [Beryllium], they use graphite).”
“As for the sail interactions with the ISM we recommend either rotating the sail so it is edge on (lower cross section) or ejecting the sail after the initial few minutes of acceleration as it is no longer needed for acceleration. However. as we desire to use the sail as a reflector for the laser communications we prefer to keep it, though a secondary reflector could be deployed later in the mission if necessary. These detailed questions will be part of the evolving design phase.”
Indeed, there are many safety hazards that have to be accounted for before any mission to interstellar space could be mounted. But as this recent study has shown – with which Professor Lubin agrees – they are not insurmountable, and a mission to Alpha Centauri (or, fingers crossed, Proxima Centauri!) could be performed if the proper precautions are taken.
Who knew the future of space travel would be every bit as cool as we’ve been led to believe – complete with lasers and shielding?
And be sure to enjoy this video from NASA 360, addressing directed-energy propulsion:
In honor of Dr. Stephen Hawking, the COSMOS center will be creating the most detailed 3D mapping effort of the Universe to date. Credit: BBC, Illus.: T.Reyes
Back in 1997, a team of leading scientists and cosmologists came together to establish the COSMOS supercomputing center at Cambridge University. Under the auspices of famed physicist Stephen Hawking, this facility and its supercomputer are dedicated to the research of cosmology, astrophysics and particle physics – ultimately, for the purpose of unlocking the deeper mysteries of the Universe.
Yesterday, in what was themed as a “tribute to Stephen Hawking”, the COSMOS center announced that it will be embarking on what is perhaps the boldest experiment in cosmological mapping. Essentially, they intend to create the most detailed 3D map of the early universe to date, plotting the position of billions of cosmic structures including supernovas, black holes, and galaxies.
This map will be created using the facility’s supercomputer, located in Cambridge’s Department of Applied Mathematics and Theoretical Physics. Currently, it is the largest shared-memory computer in Europe, boasting 1,856 Intel Xeon E5 processor cores, 31 Intel Many Integrated Core (MIC) co-processors, and 14.5 terabytes of globally shared memory.
The COSMOS IX supercomputer. Credit: cosmos.damtp.cam.ac.uk
The 3D will also rely on data obtained by two previous surveys – the ESA’s Planck satellite and the Dark Energy Survey. From the former, the COSMOS team will use the detailed images of the Cosmic Microwave Background (CMB) – the radiation leftover by the Big Ban – that were released in 2013. These images of the oldest light in the cosmos allowed physicists to refine their estimates for the age of the Universe (13.82 billion years) and its rate of expansion.
This information will be combined with data from the Dark Energy Survey which shows the expansion of the Universe over the course of the last 10 billion years. From all of this, the COSMOS team will compare the early distribution of matter in the Universe with its subsequent expansion to see how the two link up.
The project is also expected to receive a boost from the deployment of the ESA’s Euclid probe, which is scheduled for launch in 2020. This mission will measure the shapes and redshifts of galaxies (looking 10 billion years into the past), thereby helping scientists to understand the geometry of the “dark Universe” – i.e. how dark matter and dark energy influence it as a whole.
Artist impression of the Euclid probe, which is set to launch in 2020. Credit: ESA
The plans for the COSMOS center’s 3D map are will be unveiled at the Starmus science conference, which will be taking place from July 2nd to 27th, 2016, in Tenerife – the largest of the Canary Islands, located off the coast of Spain. At this conference, Hawking will be discussing the details of the COSMOS project.
In addition to being the man who brought the COSMOS team together, the theme of the project – “Beyond the Horizon – Tribute to Stephen Hawking” – was selected because of Hawking’s long-standing commitment to physics and cosmology. “Hawking is a great theorist but he always wants to test his theories against observations,” said Prof. Shellard in a Cambridge press release. “What will emerge is a 3D map of the universe with the positions of billions of galaxies.”
Hawking will also present the first ever Stephen Hawking Medal for Science Communication, an award established by Hawking that will be bestowed on those who help promote science to the public through media – i.e. cinema, music, writing and art. Other speakers who will attending the event include Neil deGrasse Tyson, Chris Hadfield, Martin Rees, Adam Riess, Rusty Schweickart, Eric Betzig, Neil Turok, and Kip Thorne.
Professor Hawking and colleagues from the Royal Society announcing the launch of the Stephen Hawking Medal for Science Communication, Dec. 16th, 2015. Credit: starmus.com
Naturally, it is hoped that the creation of this 3D map will confirm current cosmological theories, which include the current age of the Universe and whether or not the Standard Model of cosmology – aka. the Lambda Cold Dark Matter (CDM) model – is in fact the correct one. As Hawking is surely hoping, this could bring us one step closer to a Theory of Everything!
Project Starshot, an initiative sponsored by the Breakthrough Foundation, is intended to be humanity's first interstellar voyage. Credit: breakthroughinitiatives.org
For generations, human beings have fantasized about the possibility of finding extra-terrestrial life. And with our ongoing research efforts to discover new and exciting extrasolar planets (aka. exoplanets) in distant star systems, the possibility of actually visiting one of these worlds has received a real shot in the arm. Unfortunately, given the astronomical distances involved, not to mention the cost of mounting an expedition, doing so presents numerous significant challenges.
However, Russian billionaire Yuri Milner and the Breakthrough Foundation – an international organization committed to exploration and scientific research – is determined to mount an interstellar mission to Alpha Centauri, our closest stellar neighbor, in the coming years. With the backing of such big name sponsors as Mark Zuckerberg and Stephen Hawking, his latest initiative (named “Project Starshot“) aims to send a tiny spacecraft to the Alpha Centauri system to search for planets and signs of life.
