fbpx
Connect with us

The Conversation

Exploding stars are rare but emit torrents of radiation − if one happened close enough to Earth, it could threaten life on the planet

Published

on

Exploding stars are rare but emit torrents of radiation − if one happened close enough to Earth, it could threaten life on the planet

Massive dying emit large amounts of radiation.
NASA/ESA/Hubble SM4 ERO Team via AP

Chris Impey, University of Arizona

Stars like the Sun are remarkably constant. They vary in brightness by only 0.1% over years and decades, thanks to the fusion of hydrogen into helium that powers them. This will keep the Sun shining steadily for about 5 billion more years, but when stars exhaust their nuclear fuel, their deaths can lead to pyrotechnics.

The Sun will eventually die by growing large and then condensing into a type of star called a white dwarf. But stars more than eight times more massive than the Sun die violently in an explosion called a supernova.

Supernovae happen across the Milky Way only a few times a century, and these violent explosions are usually remote enough that people here on Earth don't notice. For a dying star to have any effect on life on our planet, it would have to go supernova within 100 light years from Earth.

I'm an astronomer who studies cosmology and black holes.

Advertisement

In my writing about cosmic endings, I've described the threat posed by stellar cataclysms such as supernovae and related phenomena such as gamma-ray bursts. Most of these cataclysms are remote, but when they occur closer to home they can pose a threat to life on Earth.

The death of a massive star

Very few stars are massive enough to die in a supernova. But when one does, it briefly rivals the brightness of billions of stars. At one supernova per 50 years, and with 100 billion galaxies in the universe, somewhere in the universe a supernova explodes every hundredth of a second.

An animation showing a supernova.

The dying star emits high energy radiation as gamma rays. Gamma rays are a form of electromagnetic radiation with wavelengths much shorter than light waves, meaning they're invisible to the human eye. The dying star also releases a torrent of high-energy particles in the form of cosmic rays: subatomic particles moving at close to the speed of light.

Supernovae in the Milky Way are rare, but a few have been close enough to Earth that historical discuss them. In 185 A.D., a star appeared in a place where no star had previously been seen. It was probably a supernova.

Advertisement

Observers around the world saw a bright star suddenly appear in 1006 A.D. Astronomers later it to a supernova 7,200 light years away. Then, in 1054 A.D., Chinese astronomers recorded a star visible in the daytime sky that astronomers subsequently identified as a supernova 6,500 light years away.

A man with dark hair and a beard, wearing dark clothes with an elaborate collar, resting one hand on his hip and another on a globe.
Johannes Kepler, the astronomer who observed what was likely a supernova in 1604.
Kepler-Museum in Weil der Stadt

Johannes Kepler observed the last supernova in the Milky Way in 1604, so in a statistical sense, the next one is overdue.

At 600 light years away, the red supergiant Betelgeuse in the constellation of Orion is the nearest massive star getting close to the end of its life. When it goes supernova, it will shine as bright as the full Moon for those watching from Earth, without causing any to life on our planet.

Radiation damage

If a star goes supernova close enough to Earth, the gamma-ray radiation could damage some of the planetary protection that allows life to thrive on Earth. There's a time delay due to the finite speed of light. If a supernova goes off 100 light years away, it takes 100 years for us to see it.

Astronomers have found evidence of a supernova 300 light years away that exploded 2.5 million years ago. Radioactive atoms trapped in seafloor sediments are the telltale signs of this event. Radiation from gamma rays eroded the ozone layer, which protects life on Earth from the Sun's harmful radiation. This would have cooled the climate, leading to the extinction of some ancient species.

Advertisement

Safety from a supernova with greater distance. Gamma rays and cosmic rays spread out in all directions once emitted from a supernova, so the fraction that reach the Earth decreases with greater distance. For example, imagine two identical supernovae, with one 10 times closer to Earth than the other. Earth would receive radiation that's about a hundred times stronger from the closer event.

A supernova within 30 light years would be catastrophic, severely depleting the ozone layer, disrupting the marine food chain and likely causing mass extinction. Some astronomers guess that nearby supernovae triggered a series of mass extinctions 360 to 375 million years ago. Luckily, these happen within 30 light years only every few hundred million years.

When neutron stars collide

But supernovae aren't the only events that emit gamma rays. Neutron star collisions cause high-energy phenomena ranging from gamma rays to gravitational waves.

Left behind after a supernova explosion, neutron stars are city-size balls of matter with the density of an atomic nucleus, so 300 trillion times denser than the Sun. These collisions created many of the gold and precious metals on Earth. The intense pressure caused by two ultradense objects colliding forces neutrons into atomic nuclei, which creates heavier elements such as gold and platinum.

Advertisement
Neutron stars merge when gravity pulls them together, which releases intense radiation.

A neutron star collision generates an intense burst of gamma rays. These gamma rays are concentrated into a narrow jet of radiation that packs a big punch.

If the Earth were in the line of fire of a gamma-ray burst within 10,000 light years, or 10% of the diameter of the galaxy, the burst would severely damage the ozone layer. It would also damage the DNA inside organisms' cells, at a level that would kill many simple life forms like bacteria.

That sounds ominous, but neutron stars do not typically form in pairs, so there is only one collision in the Milky Way about every 10,000 years. They are 100 times rarer than supernova explosions. Across the entire universe, there is a neutron star collision every few minutes.

Gamma-ray bursts may not hold an imminent threat to life on Earth, but over very long time scales, bursts will inevitably hit the Earth. The odds of a gamma-ray burst triggering a mass extinction are 50% in the past 500 million years and 90% in the 4 billion years since there has been life on Earth.

Advertisement

By that math, it's quite likely that a gamma-ray burst caused one of the five mass extinctions in the past 500 million years. Astronomers have argued that a gamma-ray burst caused the first mass extinction 440 million years ago, when 60% of all marine creatures disappeared.

A recent reminder

The most extreme astrophysical events have a long reach. Astronomers were reminded of this in October 2022, when a pulse of radiation swept through the solar system and overloaded all of the gamma-ray telescopes in .

It was the brightest gamma-ray burst to occur since human civilization began. The radiation caused a sudden disturbance to the Earth's ionosphere, even though the source was an explosion nearly 2 billion light years away. Life on Earth was unaffected, but the fact that it altered the ionosphere is sobering – a similar burst in the Milky Way would be a million times brighter.The Conversation

Chris Impey, Distinguished Professor of Astronomy, University of Arizona

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Advertisement

The Conversation

Under the influence and under arrest − what happens if you’re drunk in the interrogation room?

Published

on

theconversation.com – Jacqueline R. Evans, Associate Professor of Psychology, Florida International – 2024-04-26 07:28:33

In the U.S., if you waive your Miranda rights, you'll be interrogated – whether you're drunk or sober.

Photoboyko/iStock via Getty Images Plus

Jacqueline R. Evans, Florida International University

Imagine it's Friday night. You're enjoying happy hour with friends after a long . You're relaxed, indulged in several of your preferred adult beverages. Now imagine that as you the bar, a officer approaches. You're under arrest.

Advertisement

Flash forward to the police station. The officer takes you to a cramped room and reads you your Miranda rights: You have the right to remain silent, to an attorney, and all the rest. Let's say you waive those rightsmost people do – and the officer questions you for several hours.

While under the influence, would you understand your Miranda rights and appreciate the consequences of choosing to invoke or waive them? Would the statements you made during questioning be more or less reliable than how you'd respond sober? Would a jury take what the drunken you said seriously? These are the questions that legal psychologists like me and my colleagues seek to address in our research.

Suspects get similar treatment, drunk or not

When we've surveyed police, they revealed it's common to question intoxicated suspects and that they tend to use the same interrogation techniques with drunken suspects that they normally use. Surveys of community members about their experience with interrogation confirm that questioning drunken suspects is common. In fact, sometimes police even interrogate drunken juveniles.

Of course, police in the U.S. cannot legally question anyone in custody unless that person has waived their Miranda rights and chosen to to the investigator. It's a common misperception that drunken people cannot legally waive their Miranda rights and that statements given while intoxicated cannot be used against them in court. But the reality is that from a legal perspective the police can Mirandize you while you're under the influence, interrogate you, and use your statements against you.

Advertisement

arrow upwards with text describing expected impairments at increasing BAC levels

Level of impairment rises along with how much you've had to drink.

NIH National Institute on Alcohol Abuse and Alcoholism, CC BY

Consider the case of Travis Jewell. When he was arrested for fleeing a police officer in his truck, his blood alcohol level was .29, more than three times the legal limit of .08 in the U.S. The interrogator reported Jewell was slurring words and struggling to stand. Nonetheless, the court accepted his Miranda waiver, making Jewell's statements admissible during trial.

While Miranda waivers from intoxicated people may be legally valid, research from my lab suggests that when with sober individuals, someone under the influence of drugs or alcohol – even at low levels of intoxication – may be less able to comprehend their rights.

Testing how drunken ‘suspects' behave

Critically, researchers know almost nothing about how intoxicated people behave during interrogation.

Advertisement

To address this need, my colleagues and I brought university student volunteers into the lab, where we have safeguards in place to minimize risks. We had some of our participants drink enough vodka to reach a breath alcohol level of .08%, a level consistent with the legal driving limit in the U.S.

Then we set the participants up to be guilty or innocent of cheating, and interrogated each of them about potential academic misconduct. We were interested in whether, impaired or sober, they said anything incriminating or suspicious during questioning.

About two-thirds of sober participants said something suggestive of guilt, while even more intoxicated participants did. The difference in suspicious statements between the groups was not statistically significant, but our findings do indicate that intoxicated people – just like the rest of the public – are at a high risk of self-incrimination. And remember, in our study, half of the participants were innocent of the infraction they were being questioned about.

man in striped clothes sits across table from woman in suit jacket

Standard legal advice is to keep your mouth shut until you are able to meet with a lawyer.

AP Photo/Steve Helber

Advertisement

Suspicious remarks can have immediate consequences during interrogation. When a says something suggestive of guilt, it tends to increase an interrogator's belief that they're guilty. When interrogators have a stronger belief in guilt, they then tend to be more accusatory, an approach associated with false confessions.

Intoxicated suspects – guilty or innocent – are very likely to make a guilt-suggestive statement, which in turn is likely to invite more coercive interrogation approaches. This could potentially explain our recent real-world findings in Sweden that police interrogators used more confrontational techniques with intoxicated suspects than with sober suspects.

On a positive note, our work has also shown that potential jurors seem to recognize that intoxication may to less reliable statements during interrogation. They tend to give less weight to a confession from an intoxicated suspect than from a sober suspect. While that may sound reassuring, should you find yourself in that cramped interrogation room, sober or intoxicated, exercise your rights and ask for an attorney.The Conversation

Jacqueline R. Evans, Associate Professor of Psychology, Florida International University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Advertisement
Continue Reading

The Conversation

Cybersecurity researchers spotlight a new ransomware threat – be careful where you upload files

Published

on

theconversation.com – Selcuk Uluagac, Professor of Computing and Information Science, Florida International University – 2024-04-26 07:28:18

Avoiding iffy downloads is no longer enough to ensure this doesn't happen.

Olemedia/iStock via Getty Images

Selcuk Uluagac, Florida International University

You probably know better than to click on links that download unknown files onto your computer. It turns out that uploading files can get you into trouble, too.

Advertisement

's web browsers are much more powerful than earlier generations of browsers. They're able to manipulate data within both the browser and the computer's local file system. Users can send and email, listen to music or watch a movie within a browser with the click of a button.

Unfortunately, these capabilities also mean that hackers can find clever ways to abuse the browsers to trick you into letting ransomware lock up your files when you think that you're simply doing your usual tasks online.

I'm a computer scientist who studies cybersecurity. My colleagues and I have shown how hackers can gain access to your computer's files via the File System Access Application Programming Interface (API), which enables web applications in modern browsers to interact with the users' local file .

The threat applies to Google's Chrome and Microsoft's Edge browsers but not Apple's Safari or Mozilla's Firefox. Chrome accounts for 65% of browsers used, and Edge accounts for 5%. To the best of my knowledge, there have been no reports of hackers using this method so far.

Advertisement

My colleagues, who include a Google security researcher, and I have communicated with the developers responsible for the File System Access API, and they have expressed support for our work and interest in our approaches to defending against this kind of attack. We also filed a security to Microsoft but have not heard from them.

Double-edged sword

Today's browsers are almost operating systems unto themselves. They can run software programs and encrypt files. These capabilities, combined with the browser's access to the host computer's files – ones in the cloud, shared folders and external drives – via the File System Access API creates a new opportunity for ransomware.

Imagine you want to edit photos on a benign-looking online editing tool. When you upload the photos for editing, any hackers who control the malicious editing tool can access the files on your computer via your browser. The hackers would gain access to the folder you are uploading from and all subfolders. Then the hackers could encrypt the files in your file system and demand a ransom payment to decrypt them.

Today's web browsers are more powerful – and in some ways more vulnerable – than their predecessors.

Ransomware is a growing problem. Attacks have hit individuals as well as organizations, including Fortune 500 companies, , cloud service providers, cruise operators, threat-monitoring services, chip manufacturers, governments, medical centers and hospitals, insurance companies, schools, universities and even police departments. In 2023, organizations paid more than US$1.1 billion in ransomware payments to attackers, and 19 ransomware attacks targeted organizations every second.

Advertisement

It is no wonder ransomware is the No. 1 arms race today between hackers and security specialists. Traditional ransomware runs on your computer after hackers have tricked you into downloading it.

New defenses for a new threat

A team of researchers I at the Cyber-Physical Systems Security Lab at Florida International University, including postdoctoral researcher Abbas Acar and Ph.D. candidate Harun Oz, in collaboration with Google Senior Research Scientist Güliz Seray Tuncay, have been investigating this new type of potential ransomware for the past two years. Specifically, we have been exploring how powerful modern web browsers have become and how they can be weaponized by hackers to create novel forms of ransomware.

In our paper, RøB: Ransomware over Modern Web Browsers, which was presented at the USENIX Security Symposium in August 2023, we showed how this emerging ransomware strain is easy to design and how damaging it can be. In particular, we designed and implemented the first browser-based ransomware called RøB and analyzed its use with browsers running on three different major operating systems – Windows, Linux and MacOS – five cloud providers and five antivirus products.

Our evaluations showed that RøB is capable of encrypting numerous types of files. Because RøB runs within the browser, there are no malicious payloads for a traditional antivirus program to catch. This means existing ransomware detection systems face several issues against this powerful browser-based ransomware.

Advertisement

We proposed three different defense approaches to mitigate this new ransomware type. These approaches operate at different levels – browser, file system and user – and complement one another.

The first approach temporarily halts a web application – a program that runs in the browser – in order to detect encrypted user files. The second approach monitors the activity of the web application on the user's computer to identify ransomware-like patterns. The third approach introduces a new permission dialog box to inform users about the risks and implications associated with allowing web applications to access their computer's file system.

When it to protecting your computer, be careful about where you upload as well as download files. Your uploads could be giving hackers an “in” to your computer.The Conversation

Selcuk Uluagac, Professor of Computing and Information Science, Florida International University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Advertisement
Continue Reading

The Conversation

How bird flu virus fragments get into milk sold in stores, and what the spread of H5N1 in cows means for the dairy industry and milk drinkers

Published

on

theconversation.com – Noelia Silva del Rio, Associate Specialist in Cooperative Extension, Production Medicine and Food Safety, of California, Davis – 2024-04-25 14:04:50

Cows typically get over avian flu in a of weeks, but it's an economic blow for farms.

AP Photo/Charlie Litchfield

Noelia Silva del Rio, University of California, Davis; Richard V. Pereira, University of California, Davis; Robert B. Moeller, University of California, Davis; Terry W. Lehenbauer, University of California, Davis, and Todd Cornish, University of California, Davis

The discovery of viral fragments of avian flu virus in milk sold in U.S. stores suggests that the H5N1 virus may be more widespread in U.S. dairy cattle than previously realized.

Advertisement

The Food and Drug Administration was quick to stress on April 24, 2024, that it believes the commercial milk supply is safe. However, highly pathogenic avian influenza virus can make cows sick, and the flu virus's presence in herds in several states and now new federal restrictions on the movement of dairy cows between states are putting economic pressure on farmers.

Five experts in infectious diseases in cattle from the University of California, Davis – Noelia Silva del Rio, Terry Lehenbauer, Richard Pereira, Robert Moeller and Todd Cornish – explain what the test results mean, how bird flu can spread to cattle and the impact on the industry.

What are viral fragments of avian flu, and can they pose risks to people?

It's crucial to understand that the presence of viral fragments of H5N1 doesn't indicate the presence of intact virus particles that could cause disease.

The commercial milk supply maintains safety through two critical measures:

Advertisement
  • First, milk sourced from sick animals is promptly diverted or disposed of, ensuring it does not enter the food chain.

  • Second, all milk at grocery stores is heat treated to reduce pathogen load to safe levels, mainly by pasteurization. Pasteurization has been shown to effectively inactivate H5N1 in eggs, and that occurs at a lower temperature than is used for milk.

The viral fragments were detected using quantitative polymerase chain reaction testing, which is known for its exceptional sensitivity in detecting even trace amounts of viral genetic material. These fragments are only evidence that the virus was present in the milk. They aren't evidence that the virus is biologically active.

To evaluate whether the presence of the viral fragments corresponds to a virus with the capacity to replicate and cause disease, a different testing approach is necessary. Tests such as embryonated egg viability studies allow scientists to assess the virus's ability to replicate by injecting a sample into an embryonated chicken egg. That type of testing is underway.

On April 24, 2024, the FDA said it had found no reason to change its assessment that the U.S. milk supply is safe. The agency does strongly advise against consuming raw milk and products derived from it because of its inherent risks of contamination with harmful pathogens, avian flu viruses.

How does an avian flu virus get into cow's milk?

Currently, cows confirmed to have H5N1 have different symptoms than the typical flu-like symptoms observed in birds.

Advertisement

Abnormal milk and mastitis, an inflammatory response to infection, are common. While there is speculation that other bodily secretions, such as saliva, respiratory fluids, urine or feces, may also harbor the virus, that has yet to be confirmed.

The legs of a cow showing a milking device attached to the udder and tubes for the milk to flow.

Milking equipment can viruses spread.

Loic Venance/AFP via Getty Images

How waterfowl or other birds transmitted H5N1 to cattle is still under investigation. In 2015, an outbreak of highly pathogenic avian influenza in commercial poultry farms reached its peak in April and May, the same time birds migrated north. Birds can shed the virus through their oral, nasal, urine and fecal secretions. So the virus could potentially be transmitted through direct contact, ingesting contaminated feed or , or inhaling the virus.

Infected dairy cows can shed the virus in milk, and they likely can transmit it to other cows, but that still needs to be proven.

Advertisement

Contagious pathogens that cause mastitis can be transmitted through milking equipment or contaminated milker's gloves. Ongoing research will help determine whether this is also a potential transmission route for H5N1, and if so, what makes the virus thrive on mammary tissue.

If H5N1 is found to be widespread in milk, what risks can that pose for the dairy industry?

For the dairy industry, infection of cattle with H5N1 avian influenza virus creates challenges at two levels.

The overriding concern is always for the safety and healthfulness of milk and dairy products.

Existing and federal regulations and industry practices require sick cows or cows with abnormal milk to be segregated so that their milk does not enter the food supply. Proper pasteurization should kill the virus so that it cannot cause infection.

Advertisement

The American Association of Bovine Practitioners has also developed biosecurity guidelines for H5N1, focusing on key practices. These include minimizing wild birds' contact with cattle and their , managing the movement of cattle between farms, isolating affected animals, avoiding feeding unpasteurized (raw) colostrum or milk to calves and other mammals, and ensuring the use of protective personal equipment for animal caretakers.

The other major concern is for the of the dairy herd and the people who take care of the dairy cattle. A farm worker who handled dairy cows contracted H5N1 in Texas in March 2024, but such cases are rare.

No vaccines or specific therapies are available for avian influenza infections in dairy cattle. But following good sanitation and biosecurity practices for both people and cows will help to reduce risk of exposure and spread of the avian influenza virus among dairy cattle.

Advertisement

For cows that get the virus, providing supportive care, including fluids and fever reducers as needed, can help them get through the illness, which can also cause loss of appetite and affect their milk production.

Dairy farms facing an outbreak will have economic losses from caring for sick animals and the temporary reduction in milk sales. Approximately 5% to 20% of the animals in the affected herds have become ill, according to early estimates. Affected animals typically recover within 10 to 20 days.

At least 21 states have restricted importing dairy cattle to prevent the virus's spread, and the federal government announced it will require that lactating dairy cattle be tested before they can be moved between states starting April 29, 2024. While the overall impact on U.S. milk production is projected to be minor on an annual basis, it could to short-lived supply disruptions.

How worried should people be about avian flu?

The federal government's monitoring and food safety measures, along with pasteurization, provide important safeguards to protect the public from potential exposure to avian influenza virus through the food chain.

Advertisement

Drinking raw milk, however, does represent a risk for exposure to multiple diseases, including H5N1. This is why the FDA and Centers for Disease Control and Prevention strongly recommend drinking only pasteurized milk and dairy products.The Conversation

Noelia Silva del Rio, Associate Specialist in Cooperative Extension, Production Medicine and Food Safety, University of California, Davis; Richard V. Pereira, Associate Professor of Veterinary Medicine and Associate Agronomist, University of California, Davis; Robert B. Moeller, Professor of Veterinary Medicine, University of California, Davis; Terry W. Lehenbauer, Professor of Veterinary Medicine, University of California, Davis, and Todd Cornish, Professor of Veterinary Medicine, University of California, Davis

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Continue Reading

News from the South

Trending