Following George Floyd’s death at the hands of police in Minneapolis in 2020, the U.S. has undergone a national reckoning over crime prevention and police reform.

Across the country, calls went out from activists to rethink the scope and role of the police. Some on the left vowed to “defund” the police. Others on the right promised to instead “back the blue” and maintain or increase police funding.

This rhetorical tug-of-war unfolded while many cities across the country grappled with spiking crime rates during the first months of the COVID-19 pandemic.

Blaming crime on Democratic city leaders was a centerpiece of Donald Trump’s 2024 presidential campaign. He repeatedly made claims about crime spikes in recent years without evidence or context.

More recently, Republican congressional leaders have called several Democratic mayors from across the country to testify before Congress about their sanctuary city policies that are aimed at protecting noncitizens from deportation. These congressional politicians have asserted that these Democratic mayors – Brandon Johnson of Chicago, Mike Johnston of Denver, Michelle Wu of Boston, and Eric Adams of New York – have “created a public safety nightmare” in their cities by allowing immigrants without legal authorization to stay there.

Journalists and politicians on both sides of the aisle have claimed that local election results over the past four years in places like San Francisco and Los Angeles reflect a widespread frustration with Democratic policies on crime in cities.

Under this argument, Democratic city leaders need to change their approach on crime to satisfy voters. It’s become a political axiom of sorts that policies championed largely by Democratic city leaders over the past half decade have resulted in rising crime levels.

As researchers of politics and public policy, we wanted to figure out if that was true.

Neither party does a better job

As any student of introductory statistics learns, correlation doesn’t imply causation. Looking at increases or decreases in crime rates in Republican or Democratic cities and claiming either party is to blame would be making exactly this error: confusing correlation with causation.

We put to the test the argument that one side or the other is better at fighting crime in our research published in January 2025. By employing three decades of data on mayoral elections from across the country, we were able to disentangle city leaders’ partisanship from other features of cities.

Contrary to much of the political rhetoric and media coverage aimed at most Americans, our results show that neither party is doing a better job at actually causing crime to decrease.

In Dallas, Mayor Eric Johnson has claimed that Democratic leaders aren’t taking public safety seriously and that the Democratic Party is “with the criminals.” Johnson switched from being a Democrat to a Republican in 2023 and attributes his decision at least partially to this partisan difference on crime and policing and the seriousness with which he takes this policy issue.

But our research shows that Johnson’s and others’ claims about Democratic cities becoming more dangerous just aren’t true: Mayors from the Democratic Party aren’t making cities any more – or less – dangerous than mayors from the Republican Party.

Nor, it turns out, is there any support for claims by some progressive Democrats that they would reduce the role – and enormous budgets – of police departments in cities across the country.

When we examined the number of sworn police officers in cities and how much money those cities spend on the police, Democratic and Republican mayors alike have had surprisingly little influence on police department budgets or sizes.

In other words, Democrats aren’t cutting police budgets, nor are Republicans increasing police budgets. Most cities have increased police budgets in the past few years, possibly due to pressure from police unions.

‘Crime is nonpartisan’

It turns out that campaign promises from both sides of the partisan aisle about crime and policing have little bearing on what’s happening on the ground in most cities and police departments across the country.

Neither party is doing a better job at reducing crime. Nor is either party actually addressing the ballooning financial cost of local police forces in the U.S., nor the long-term reputational costs from police misconduct for trust in the police and government more broadly.

As others have said: crime is nonpartisan.

Crime has decreased across the U.S. during the past three decades overall, and the isolated cities where crime has increased recently can reverse these temporary trends.

Partisan blame narratives do little to actually lower crime and make neighborhoods safer, though.

There are real evidence-backed policies that reduce crime – such as youth jobs programs in Chicago and Boston. Other policies reduce racial disparities in the criminal justice system – such as alternative 911 response programs that use unarmed behavioral health workers to respond to some types of emergencies.

These policies and interventions might not be as slogan-worthy as “defund the police” or “back the blue.” Nor is implementing these policies as politically convenient as blaming sanctuary city mayors. But research shows that they work and can move cities toward the shared goal of improved public safety for their residents.

Justin de Benedictis-Kessner, Associate Professor of Public Policy, Harvard Kennedy School and Christopher S. Warshaw, Professor of Political Science, George Washington University

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

A team of astronomers announced on April 16, 2025, that in the process of studying a planet around another star, they had found evidence for an unexpected atmospheric gas. On Earth, that gas – called dimethyl sulfide – is mostly produced by living organisms.

In April 2024, the James Webb Space Telescope stared at the host star of the planet K2-18b for nearly six hours. During that time, the orbiting planet passed in front of the star. Starlight filtered through its atmosphere, carrying the fingerprints of atmospheric molecules to the telescope.

By comparing those fingerprints to 20 different molecules that they would potentially expect to observe in the atmosphere, the astronomers concluded that the most probable match was a gas that, on Earth, is a good indicator of life.

I am an astronomer and astrobiologist who studies planets around other stars and their atmospheres. In my work, I try to understand which nearby planets may be suitable for life.

K2-18b, a mysterious world

To understand what this discovery means, let’s start with the bizarre world it was found in. The planet’s name is K2-18b, meaning it is the first planet in the 18th planetary system found by the extended NASA Kepler mission, K2. Astronomers assign the “b” label to the first planet in the system, not “a,” to avoid possible confusion with the star.

K2-18b is a little over 120 light-years from Earth – on a galactic scale, this world is practically in our backyard.

Although astronomers know very little about K2-18b, we do know that it is very unlike Earth. To start, it is about eight times more massive than Earth, and it has a volume that’s about 18 times larger. This means that it’s only about half as dense as Earth. In other words, it must have a lot of water, which isn’t very dense, or a very big atmosphere, which is even less dense.

Astronomers think that this world could either be a smaller version of our solar system’s ice giant Neptune, called a mini-Neptune, or perhaps a rocky planet with no water but a massive hydrogen atmosphere, called a gas dwarf.

Another option, as University of Cambridge astronomer Nikku Madhusudhan recently proposed, is that the planet is a “hycean world”.

That term means hydrogen-over-ocean, since astronomers predict that hycean worlds are planets with global oceans many times deeper than Earth’s oceans, and without any continents. These oceans are covered by massive hydrogen atmospheres that are thousands of miles high.

Astronomers do not know yet for certain that hycean worlds exist, but models for what those would look like match the limited data JWST and other telescopes have collected on K2-18b.

This is where the story becomes exciting. Mini-Neptunes and gas dwarfs are unlikely to be hospitable for life, because they probably don’t have liquid water, and their interior surfaces have enormous pressures. But a hycean planet would have a large and likely temperate ocean. So could the oceans of hycean worlds be habitable – or even inhabited?

Detecting DMS

In 2023, Madhusudhan and his colleagues used the James Webb Space Telescope’s short-wavelength infrared camera to inspect starlight that filtered through K2-18b’s atmosphere for the first time.

They found evidence for the presence of two simple carbon-bearing molecules – carbon monoxide and methane – and showed that the planet’s upper atmosphere lacked water vapor. This atmospheric composition supported, but did not prove, the idea that K2-18b could be a hycean world. In a hycean world, water would be trapped in the deeper and warmer atmosphere, closer to the oceans than the upper atmosphere probed by JWST observations.

Intriguingly, the data also showed an additional, very weak signal. The team found that this weak signal matched a gas called dimethyl sulfide, or DMS. On Earth, DMS is produced in large quantities by marine algae. It has very few, if any, nonbiological sources.

This signal made the initial detection exciting: on a planet that may have a massive ocean, there is likely a gas that is, on Earth, emitted by biological organisms.

Scientists had a mixed response to this initial announcement. While the findings were exciting, some astronomers pointed out that the DMS signal seen was weak and that the hycean nature of K2-18b is very uncertain.

To address these concerns, Mashusudhan’s team turned JWST back to K2-18b a year later. This time, they used another camera on JWST that looks for another range of wavelengths of light. The new results – announced on April 16, 2025 – supported their initial findings.

These new data show a stronger – but still relatively weak – signal that the team attributes to DMS or a very similar molecule. The fact that the DMS signal showed up on another camera during another set of observations made the interpretation of DMS in the atmosphere stronger.

Madhusudhan’s team also presented a very detailed analysis of the uncertainties in the data and interpretation. In real-life measurements, there are always some uncertainties. They found that these uncertainties are unlikely to account for the signal in the data, further supporting the DMS interpretation. As an astronomer, I find that analysis exciting.

Is life out there?

Does this mean that scientists have found life on another world? Perhaps – but we still cannot be sure.

First, does K2-18b really have an ocean deep beneath its thick atmosphere? Astronomers should test this.

Second, is the signal seen in two cameras two years apart really from dimethyl sulfide? Scientists will need more sensitive measurements and more observations of the planet’s atmosphere to be sure.

Third, if it is indeed DMS, does this mean that there is life? This may be the most difficult question to answer. Life itself is not detectable with existing technology. Astronomers will need to evaluate and exclude all other potential options to build their confidence in this possibility.

The new measurements may lead researchers toward a historic discovery. However, important uncertainties remain. Astrobiologists will need a much deeper understanding of K2-18b and similar worlds before they can be confident in the presence of DMS and its interpretation as a signature of life.

Scientists around the world are already scrutinizing the published study and will work on new tests of the findings, since independent verification is at the heart of science.

Moving forward, K2-18b is going to be an important target for JWST, the world’s most sensitive telescope. JWST may soon observe other potential hycean worlds to see if the signal appears in the atmospheres of those planets, too.

With more data, these tentative conclusions may not stand the test of time. But for now, just the prospect that astronomers may have detected gasses emitted by an alien ecosystem that bubbled up in a dark, blue-hued alien ocean is an incredibly fascinating possibility.

Regardless of the true nature of K2-18b, the new results show how using the JWST to survey other worlds for clues of alien life will guarantee that the next years will be thrilling for astrobiologists.

Daniel Apai, Associate Dean for Research and Professor of Astronomy and Planetary Sciences, University of Arizona

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