Photo source: Morning Bew

The Intergovernmental Panel on Climate Change (IPCC), an official UN task force, released a 3,949-page report from 234 scientists yesterday that called current climate change trends a “code red for humanity.”

Here’s what you need to know

It’s all our fault. If there was any doubt that maybe we could partly blame volcanoes for climate change, the IPCC put it to rest. “It is unequivocal that human influence has warmed the atmosphere, ocean, and land,” the scientists wrote. They found that human activity has increased the global average temperature by about 2 degrees Fahrenheit since the Industrial Revolution of the 19th century.

Weather goes mid-2000s candy “EXXTREME!” Tropical storms, heat waves, wildfires, droughts, and flooding are all expected to get more severe and more frequent if climate change continues at its current rate, the report said.

• More extreme weather shouldn’t just be thought of in the future tense, but the here and now. Just last week Greece, Turkey, and much of the Western US experienced some of their worst wildfires in history. 

All eyes on the energy industry. The report blamed one particular human activity for exacerbating climate change: burning fossil fuels. CO2 levels in the atmosphere are the highest they’ve been in 2 million years. 

• “This report must sound a death knell for coal and fossil fuels before they destroy our planet,“ UN Secretary-general Antonio Guterres said. 

There’s a little hope. Since the IPCC’s last big report in 2013, countries have done a better job in curbing carbon emissions. But they need to speed up those cuts dramatically, the report argued. Otherwise, it will be nearly impossible to keep global temps from spiraling higher.

Looking ahead…world leaders will head to Glasgow, Scotland, in November for the pivotal COP26 international climate talks. They’ll be tasked with taking the IPCC’s scientific report and turning it into meaningful policy. 

Source: Morning Brew

Astronomers continue to develop computer simulations to help future observatories better home in on black holes, the most elusive inhabitants of the universe.

Though black holes likely exist abundantly in the universe, they are notoriously hard to see. Scientists did not capture the first radio image of a black hole until 2019, and only about four dozen black hole mergers have been detected through their signature gravitational ripples since the first detection in 2015.

So scientists look to black hole simulations to gain crucial insight that will help find more mergers with future missions. 

Some of these simulations, created by scientists like astrophysicist Scott Noble, track supermassive black hole binary systems. That is where two monster black holes like those found in the centers of galaxies orbit closely around each other until they eventually merge.

In 2019 the Event Horizon Telescope (EHT) gave us the first direct image of a black hole. On one hand, the image it produced was rather unimpressive. Just a circular blur of light surrounding a dark central region. On the other hand, subtle characteristics of the image hold tremendous information about the size and rotation of the black hole. Most of the details of the black hole image are blurred by the limits of the EHT. But the next generation EHT should provide a sharper view, and could reveal the dark edge of a black hole’s event horizon.

A black hole doesn’t emit light itself. Any light that crosses its event horizon is forever trapped. The glowing ring we see in the EHT image of M87* is caused by the background radio glow of gas and dust surrounding the black hole. Some of that light passes very close to the black hole and is gravitationally lensed in our direction. The closest limit that light can graze the black hole and reach us is known as the photon ring.

If we could observe the black hole perfectly, the photon ring would be a thin bright line. Some of the light from the photon ring is scattered before it reaches us, and combined with the resolution limits of the EHT this creates the blurred image we see. But the next generation EHT will have a higher resolution and will be able to capture images in a shorter period of time. This will allow detailed images not just of M87*, but also of the supermassive black hole in our galaxy.

One of the things the ngEHT could reveal is multiple layers of lensed light. Most of the light we see surrounding the black hole is that of the photon ring. That is, the strongly lensed light that grazed the black hole. But some light will make a full loop around the black hole before heading our way, and a small amount will make multiple loops. Each type of photon path creates a different layer of light ring around the black hole. If we can pull apart these layers, we will better understand the nature of gravity near a black hole.

The gravitational field near a black hole is so strong that it distorts not only the glow of the photon ring but also the shadow of the event horizon. So while the event horizon is truly spherical, our view of the event horizon can be distorted by the black hole’s gravity. In this latest work, the team shows how we might be able to observe both the photon ring and the inner shadow. By comparing the two we would gain a deep understanding of black hole dynamics, including information about how light and matter are captured by a black hole.

In time, we might finally be able to see the dark shadow of gravity itself.

Source: Univese Today