from the world's big
Where do atoms come from? Billions of years of cosmic fireworks.
The periodic table was a lot simpler at the beginning of 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: Don, you've asked a question that's related to what I think is my absolute favorite fact in the universe, and that is that we are made of dead stars. And that's literally true. The atoms in our bodies were actually created inside the cause of stars that then exploded, and died, or unraveled into space.
And so your question about the periodic table is very interesting. What was the periodic table like at the beginning of the universe, the moment of the Big Bang? Well, one thing I can say, it was a lot simpler. The Big Bang, when it went off, produced basically three elements. Almost everything was hydrogen. There was a little bit of helium, and a tiny, tiny little smattering of lithium as well.
So those three elements were around just a couple of minutes after the formation of the universe, but nothing else. And that's actually not a theory. That's actually something we can observe. One of the wonderful things about being an astronomer is, as you look out into space, farther and farther away, the light has taken longer to get to you. And the farthest we can see is actually back to a time only about 400,000 years after the Big Bang. And really, at that time, there was nothing but very hot hydrogen gas, and a little bit of helium and lithium as well.
So everything larger than that, every atom more complex had to be formed inside a star. Over time, stars like the sun are pretty good, over the life cycle, at producing things like carbon and oxygen. They don't really get much more far off the periodic table than that. If you want to go any farther than the element, iron, you actually need a very violent explosion, a supernova explosion.
The cores of very massive stars and by that, I mean stars that are 10, 20, maybe even as much as 50 times the mass of the sun, their cores are much hotter, because the gravity crushes things down, and the temperature goes up many, many millions of degrees hotter than inside the sun. So these stars can actually form bigger and bigger atoms. The hotter the temperature, the denser the core, the more you can ram things together and actually form bigger and bigger atoms over time.
But there's a very special thing that happens when you get to the atom, iron. And it's something you've actually heard about but you may never have thought of. And that when people think about getting energy out of a nuclear reaction you've heard about fusion reactions. So like a fusion bomb, actually, takes hydrogen, fuses it together to make helium, and that creates energy. And that's a nuclear bomb. The sun also runs on that particular reaction, fusing hydrogen together. But then you also heard that there's something called fission. And this is how, say, a uranium bomb would work. A uranium nucleus has many, many particles inside it you actually get energy out of breaking it up and forming two smaller nuclei that are actually a bit denser, and they hold together better. And so you get energy out of breaking them apart.
And the element, iron, is exactly halfway between those two processes. So you've been getting energy by fusing things together until you get to iron. And iron is the first nucleus where you don't get any energy out of fusing. From anything bigger, now, you get energy out of ripping apart, fission.
So iron is what sets off a supernova explosion. When a star tries to fuse iron together, it absorbs energy. And that's not great for the star. The core collapses. And that huge collapse creates this giant wave of heat and the formation of many, many new elements after that. So anything heavier than iron has to be created in a supernova explosion.
Now, there are some elements, heavier still, that even supernova energies don't really get up quite high enough to make. And this is something we only found out recently, in the last couple of years. Elements like gold gold is actually a really interesting one platinum; interestingly enough, bismuth; and all the big things, like uranium and all of the really large atoms; they have to be formed by something that seems almost preposterous, but we have observed this happening two neutron stars colliding.
So neutron stars are the cores of dead stars. They're super-compressed. The density of a neutron star is about a Mount Everest worth of mass in every square centimeter. So think about crushing Mount Everest into a little cube like that. The entire star, which is only about 10 miles across, is actually that density.
And that means you have a tremendous amount of nuclear components-- neutrons, protons, really close together. And two neutron stars collide. And when that happens, you make all of these very heavy elements up, like gold, and platinum, and uranium, and all the big stuff. And again, this is not something that we just know theoretically. We actually have observed this happening. Recently, we observed two neutron stars colliding. And in that single explosion, 10,000 times the mass of the Earth in gold came out of that explosion. It was tremendous. So we definitely know where those atoms come from now. We observed that happening.
So to recap, at the beginning of the universe, you had three elements mostly hydrogen, a little bit of helium, tiny little bit of lithium. Now we have the entire periodic table. And a lot of those are formed in stars like the sun. Anything past iron has to be formed much more violently, in a supernova explosion or, in the case of very large atoms, two colliding neutron stars. And over billions of years, we've filled out the periodic table that way.
- Michelle Thaller's "absolute favorite fact in the universe" is that we are made of dead stars.
- The Big Bang, when it went off, produced basically three elements: hydrogen, helium, and lithium. Every atom more complex had to be formed inside a star. Over time, stars such as the sun produce things like carbon and oxygen.
- They don't really get much more far off the periodic table than that. If you want to go any farther than the element iron, then you actually need a very violent explosion, a supernova explosion.
- Why number 137 is one of the greatest mysteries in physics - Big Think ›
- Hints of the 4th dimension have been detected by physicists - Big ... ›
- Where do atoms come from? Billions of years of cosmic fireworks ... ›
If machines develop consciousness, or if we manage to give it to them, the human-robot dynamic will forever be different.
- Does AI—and, more specifically, conscious AI—deserve moral rights? In this thought exploration, evolutionary biologist Richard Dawkins, ethics and tech professor Joanna Bryson, philosopher and cognitive scientist Susan Schneider, physicist Max Tegmark, philosopher Peter Singer, and bioethicist Glenn Cohen all weigh in on the question of AI rights.
- Given the grave tragedy of slavery throughout human history, philosophers and technologists must answer this question ahead of technological development to avoid humanity creating a slave class of conscious beings.
- One potential safeguard against that? Regulation. Once we define the context in which AI requires rights, the simplest solution may be to not build that thing.
Duke University researchers might have solved a half-century old problem.
- Duke University researchers created a hydrogel that appears to be as strong and flexible as human cartilage.
- The blend of three polymers provides enough flexibility and durability to mimic the knee.
- The next step is to test this hydrogel in sheep; human use can take at least three years.
Duke researchers have developed the first gel-based synthetic cartilage with the strength of the real thing. A quarter-sized disc of the material can withstand the weight of a 100-pound kettlebell without tearing or losing its shape.
Photo: Feichen Yang.<p>That's the word from a team in the Department of Chemistry and Department of Mechanical Engineering and Materials Science at Duke University. Their <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/adfm.202003451" target="_blank">new paper</a>, published in the journal,<em> Advanced Functional Materials</em>, details this exciting evolution of this frustrating joint.<br></p><p>Researchers have sought materials strong and versatile enough to repair a knee since at least the seventies. This new hydrogel, comprised of three polymers, might be it. When two of the polymers are stretched, a third keeps the entire structure intact. When pulled 100,000 times, the cartilage held up as well as materials used in bone implants. The team also rubbed the hydrogel against natural cartilage a million times and found it to be as wear-resistant as the real thing. </p><p>The hydrogel has the appearance of Jell-O and is comprised of 60 percent water. Co-author, Feichen Yang, <a href="https://today.duke.edu/2020/06/lab-first-cartilage-mimicking-gel-strong-enough-knees" target="_blank">says</a> this network of polymers is particularly durable: "Only this combination of all three components is both flexible and stiff and therefore strong." </p><p> As with any new material, a lot of testing must be conducted. They don't foresee this hydrogel being implanted into human bodies for at least three years. The next step is to test it out in sheep. </p><p>Still, this is an exciting step forward in the rehabilitation of one of our trickiest joints. Given the potential reward, the wait is worth it. </p><p><span></span>--</p><p><em>Stay in touch with Derek on <a href="http://www.twitter.com/derekberes" target="_blank">Twitter</a>, <a href="https://www.facebook.com/DerekBeresdotcom" target="_blank">Facebook</a> and <a href="https://derekberes.substack.com/" target="_blank">Substack</a>. His next book is</em> "<em>Hero's Dose: The Case For Psychedelics in Ritual and Therapy."</em></p>
What would it be like to experience the 4th dimension?
Physicists have understood at least theoretically, that there may be higher dimensions, besides our normal three. The first clue came in 1905 when Einstein developed his theory of special relativity. Of course, by dimensions we’re talking about length, width, and height. Generally speaking, when we talk about a fourth dimension, it’s considered space-time. But here, physicists mean a spatial dimension beyond the normal three, not a parallel universe, as such dimensions are mistaken for in popular sci-fi shows.
An algorithm may allow doctors to assess PTSD candidates for early intervention after traumatic ER visits.
- 10-15% of people visiting emergency rooms eventually develop symptoms of long-lasting PTSD.
- Early treatment is available but there's been no way to tell who needs it.
- Using clinical data already being collected, machine learning can identify who's at risk.
The psychological scars a traumatic experience can leave behind may have a more profound effect on a person than the original traumatic experience. Long after an acute emergency is resolved, victims of post-traumatic stress disorder (PTSD) continue to suffer its consequences.
In the U.S. some 30 million patients are annually treated in emergency departments (EDs) for a range of traumatic injuries. Add to that urgent admissions to the ED with the onset of COVID-19 symptoms. Health experts predict that some 10 percent to 15 percent of these people will develop long-lasting PTSD within a year of the initial incident. While there are interventions that can help individuals avoid PTSD, there's been no reliable way to identify those most likely to need it.
That may now have changed. A multi-disciplinary team of researchers has developed a method for predicting who is most likely to develop PTSD after a traumatic emergency-room experience. Their study is published in the journal Nature Medicine.
70 data points and machine learning
Image source: Creators Collective/Unsplash
Study lead author Katharina Schultebraucks of Columbia University's Department Vagelos College of Physicians and Surgeons says:
"For many trauma patients, the ED visit is often their sole contact with the health care system. The time immediately after a traumatic injury is a critical window for identifying people at risk for PTSD and arranging appropriate follow-up treatment. The earlier we can treat those at risk, the better the likely outcomes."
The new PTSD test uses machine learning and 70 clinical data points plus a clinical stress-level assessment to develop a PTSD score for an individual that identifies their risk of acquiring the condition.
Among the 70 data points are stress hormone levels, inflammatory signals, high blood pressure, and an anxiety-level assessment. Says Schultebraucks, "We selected measures that are routinely collected in the ED and logged in the electronic medical record, plus answers to a few short questions about the psychological stress response. The idea was to create a tool that would be universally available and would add little burden to ED personnel."
Researchers used data from adult trauma survivors in Atlanta, Georgia (377 individuals) and New York City (221 individuals) to test their system.
Of this cohort, 90 percent of those predicted to be at high risk developed long-lasting PTSD symptoms within a year of the initial traumatic event — just 5 percent of people who never developed PTSD symptoms had been erroneously identified as being at risk.
On the other side of the coin, 29 percent of individuals were 'false negatives," tagged by the algorithm as not being at risk of PTSD, but then developing symptoms.
Image source: Külli Kittus/Unsplash
Schultebraucks looks forward to more testing as the researchers continue to refine their algorithm and to instill confidence in the approach among ED clinicians: "Because previous models for predicting PTSD risk have not been validated in independent samples like our model, they haven't been adopted in clinical practice." She expects that, "Testing and validation of our model in larger samples will be necessary for the algorithm to be ready-to-use in the general population."
"Currently only 7% of level-1 trauma centers routinely screen for PTSD," notes Schultebraucks. "We hope that the algorithm will provide ED clinicians with a rapid, automatic readout that they could use for discharge planning and the prevention of PTSD." She envisions the algorithm being implemented in the future as a feature of electronic medical records.
The researchers also plan to test their algorithm at predicting PTSD in people whose traumatic experiences come in the form of health events such as heart attacks and strokes, as opposed to visits to the emergency department.