from the world's big
Cosmic Riddle: How Can This Star Be Older Than the Universe?
Astronomers have gotten good at dating stars. But this one has them stumped.
It’s drilled into us since elementary school... the Big Bang created everything. Or did it? There’s actually one celestial body, the Methuselah star (HD 140283) which has astronomers stumped. It’s thought to be 14.5 billion years old. But the Big Bang occurred 13.8 billion years ago.
Astronomers determine a star’s age by its physical properties. Temperature, luminosity, and radiance are all studied closely in order to properly date one. A star’s lifespan however depends on how much metal and mass it contains. Older stars will have low mass and low metallicity.
“Metal” here is considered the byproducts of a fusion reaction in the star’s core. Some of the earliest stars had no metals in them. But as stars die, their remains become part of new stars, and those adopt the metals created by their predecessors.
So is this star going to cause a paradigm shift in how we view the cosmos? Probably not. It’s unlikely that the universe is 14.5 billion years old. How do scientists know the universe’s age anyway?
Star HD 140283 could be older than the universe itself. ESA/Hubble.
One way to know is to measure the temperature and pressure of the cosmic microwave background. This is a layer of radiation inhabiting deep space thought to be the afterglow from the Big Bang. It’s the most distant light we’re able to detect. The Hubble Constant or the expansion rate of the universe also helps scientists date a star.
Another way is to study stars and star clusters. We know how stars are formed, how their fusion reactions start, their efficiency level, and how they die. It can be difficult however when a star is in midlife to define how old it actually is. Understanding its composition can help.
Astronomers can get a handle on a star’s age by measuring how much carbon, oxygen, and iron it contains. The spectrum of starlight contains dark lines called Fraunhofer lines. These are formed by different elements in the star interacting with its light. But studying these lines, astronomers can determine a star’s composition.
The lifecycle of a star. NASA Goddard Space Flight Center.
Other methods include looking at star formation, star cluster formation, and the creation and development of galaxies. Most scientists say our calculations for the age of the universe, with all these considerations taken together is pretty solid, give or take 100 million years.
That’s why it was so shocking that previous research had Methuselah at up to 16 billion years old. A team recently reevaluated the star and updated its age, which they say is compatible with our current cosmological model. In this study, lead author Howard Bond and colleagues looked at the star’s brightness, distance, structure, and composition, to reevaluate the star's age. Bond is a professor in the Astronomy & Astrophysics department at the University of Pennsylvania.
Methuselah is a low metallicity subgiant on its way to becoming a red giant. This is when it’s exhausted its hydrogen core. It’ll expand for a time, then shrink to a white dwarf, or else end in supernova.
Bond and his team used the Hubble space telescope to get a better understanding of the distance of star HD 140283, in conjunction with the principle of parallax. This is the experience of things looking as if they cross at a distance, when in actuality they remain parallel. Think of when you look down train tracks. The tracks seem to meet at the vanishing point.
The Pleiades star cluster. ESA/Hubble.
Bond and colleagues thought they could get a more accurate measurement of distance by understanding the variance between the position of Earth’s orbit and Hubble’s. They were right. Methuselah is 190.1 light-years away, researchers found. It’s moving at a high rate of speed, 800,000 mph (1.3 million km/h) and has an unusually long orbit. These may be symptoms of its decline.
Getting a better grip on the star’s distance, they were able to calculate its brightness. From there, they could figure the star’s age. Bond said there’s a level of uncertainty, which could add or subtract 800 million years. A subtraction would make it just a tad younger than the universe itself. The team also tried to get a better understanding of the star’s burn rate, which could also help date it.
Bond and colleagues believe the star has a high ration of oxygen-to-iron. This might also make it younger than first predicted. Researchers are pretty sure further calculations will bring the star’s age down some more. The results of their study were published in the journal Solar and Stellar Astrophysics.
To learn more about this cosmological riddle, click here:
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.
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>
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.