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By Chad Hanna, Penn State 

Scientists first detected ripples in space known as gravitational waves from the merger of two black holes in September 2015. This discovery marked the culmination of a 100-year quest to prove one of Einstein’s predictions.

Two years after this watershed moment in physics came a second late-summer breakthrough in August 2017: the first detection of gravitational waves accompanied by electromagnetic waves from the merger of two neutron stars.

Gravitational waves are exciting to scientists because they provide a completely new view of the universe. Conventional astronomy relies on electromagnetic waves – like light – but gravitational waves are an independent messenger that can emanate from objects that don’t emit light. Gravitational wave detection has unlocked the universe’s dark side, giving scientists access to phenomena never observed before.

As a gravitational wave physicist with over 20 years of research experience in the LIGO Scientific Collaboration, I have seen firsthand how these discoveries have transformed scientists’ knowledge of the universe.

This summer, in 2025, scientists with the LIGO, Virgo and KAGRA collaboration also marked a new milestone. After a long hiatus to upgrade its equipment, this collaboration just released an updated list of gravitational wave discoveries. The discoveries on this list provide researchers with an unprecedented view of the universe featuring, among other things, the clearest gravitational wave detection yet.

What are gravitational waves?

Albert Einstein first predicted the existence of gravitational waves in 1916. According to Einstein’s theory of gravity, known as general relativity, massive, dense celestial objects bend space and time.

When these massive objects, like black holes and neutron stars – the end product of a supernova – orbit around each other, they form a binary system. The motion from this system dynamically stretches and squeezes the space around these objects, sending gravitational waves across the universe. These waves ever so slightly change the distance between other objects in the universe as they pass.

Detecting gravitational waves requires measuring distances very carefully. The LIGO, Virgo and KAGRA collaboration operates four gravitational wave observatories: two LIGO observatories in the U.S., the Virgo observatory in Italy and the KAGRA observatory in Japan.

Each detector has L-shaped arms that span over two miles. Each arm contains a cavity full of reflected laser light that precisely measures the distance between two mirrors.

As a gravitational wave passes, it changes the distance between the mirrors by 10^-18 meters — just 0.1% of the diameter of a proton. Astronomers can measure how the mirrors oscillate to track the orbit of black holes.

These tiny changes in distance encode a tremendous amount of information about their source. They can tell us the masses of each black hole or neutron star, their location and whether they are spinning on their own axis.

A neutron star-black hole merger

As mentioned previously, the LIGO, Virgo and KAGRA collaboration recently reported 128 new binary mergers from data taken between May 24, 2023, and Jan. 16, 2024 – which more than doubles the previous count.

Among these new discoveries is a neutron star–black hole merger. This merger consists of a relatively light black hole with mass between 2.5 and 4.5 times the mass of our Sun paired with a neutron star that is 1.4 times the mass of our Sun.

In this kind of system, scientists theorize that the black hole tears the neutron star apart before swallowing it, which releases electromagnetic waves. Sadly, the collaboration didn’t manage to detect any such electromagnetic waves for this particular system.

Detecting an electromagnetic counterpart to a black hole tearing apart a neutron star is among the holy grails of astronomy and astrophysics. These electromagnetic waves will provide the rich datasets required for understanding both the extreme conditions present in matter, and extreme gravity. Scientists hope for better fortune the next time the detectors spot such a system.

A massive binary and clear gravitational waves

In July 2025, the LIGO, Virgo and KAGRA collaboration also announced they’d found the most massive binary black hole merger ever detected. The combined mass of this system is more than 200 times the mass of our Sun. And, one of the two black holes in this system likely has a mass that scientists previously assumed could not be produced from the collapse of a single star.

The most recent discovery announced by the LIGO, Virgo and KAGRA collaboration, in September 2025, is the clearest gravitational wave observation to date. This event is a near clone of the first gravitational wave observation from 10 years ago, but because LIGO’s detectors have improved over the last decade, it stands out above the noise three times as much as the first discovery.

Because the observed gravitational wave signal is so clear, scientists could confirm that the final black hole that formed from the merger emitted gravitational waves exactly as it should according to general relativity.

They also showed that the surface area of the final black hole was greater than the surface area of the initial black holes combined, which implies that the merger increased the entropy, according to foundational work from Stephen Hawking and Jacob Bekenstein. Entropy measures how disordered a system is. All physical interactions are expected to increase the disorder of the universe, according to thermodynamics. This recent discovery showed that black holes obey their own laws similar to thermodynamics.

The beginning of a longer legacy

The LIGO, Virgo and KAGRA collaboration’s fourth observing run is ongoing and will last through November. My colleagues and I anticipate more than 100 additional discoveries within the coming year.

New observations starting in 2028 may bring the tally of binary mergers to as many as 1,000 by around 2030, if the collaboration keeps its funding.

Gravitational wave observation is still in its infancy. A proposed upgrade to LIGO called A# may increase the gravitational wave detection rate by another factor of 10. Proposed new observatories called Cosmic Explorer and the Einstein Telescope that may be built in 10 to 20 years would increase the rate of gravitational wave detection by 1,000, relative to the current rate, by further reducing noise in the detector.

About the Author:

Chad Hanna, Professor of Physics, Penn State

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

By Ryan Herzog, Gonzaga University 

The Federal Reserve on Sept. 17, 2025, cut its target interest rate as it shifts focus from fighting inflation to supporting the choppy labor market.

As financial markets expected, the Fed lowered rates a quarter point to a range of 4% to 4.25%, its first cut since December 2024.

The Fed’s decision to begin cutting rates comes as evidence mounts that the U.S. labor market is losing momentum. The headline unemployment rate has stayed steady at near record lows, but the underlying trends are more concerning.

At the same time, the fight against inflation is not over yet. While a cooling jobs market could lead to a recession, cutting rates too much could drive inflation higher.

So if you’re the Fed, what do you do?

I’m an economist who tracks labor market data and monetary policy, examining how changes in hiring, wages and unemployment influence the Federal Reserve’s efforts to steer the economy. There’s an incredibly large amount of data the Fed, investors, economists like me and many others use to understand the state of the economy – and much of it often tells conflicting stories.

Here are some the data points I’ve been following most closely to better understand where the U.S. economy might go from here – and the tough choices the Fed has to make.

Underlying trouble in the labor market

The labor market looks stable on the surface, but more granular data tells a different story.

The unemployment rate has remained close to historic lows at 4.3% as of August 2025, according to the U.S. Bureau of Labor Statistics.

But the number of long-term unemployed – people out of work for 27 weeks or longer – rose to 1.9 million in August, up 385,000 from a year earlier. These workers now make up 25.7% of all unemployed people, the highest share since February 2022. Persistent long-term joblessness often signals deeper cracks forming in the labor market.

At the same time, new claims for unemployment benefits are spiking. Initial claims for unemployment insurance – a leading indicator of labor market stress – jumped by 27,000 to 263,000 for the week ending Sept. 6, according to the U.S. Department of Labor. That’s the sharpest increase in months and well above economists’ forecasts. It suggests layoffs are becoming more common.

We also got news that past payroll growth was overstated. In a process the Bureau of Labor Statistics undertakes annually to double-check its data, the bureau recently revised its jobs data downward from April 2024 through March 2025 by 911,000. In other words, the economy created roughly 75,000 fewer jobs per month than previously reported. This implies the labor market was weaker than it appeared all along.

Finally, workers are losing confidence. The Federal Reserve Bank of New York reported in August that the confidence of people who lost their jobs in finding another fell to its lowest level – 44.9% – since it started surveying consumers in June 2013. That’s another sign workers are feeling less secure about their prospects.

Taken together, these data points paint a clear picture: The labor market is not collapsing, but it is softening. That helps explain why the Fed is beginning to cut rates now – hoping to stimulate spending – before the job market breaks more sharply.

Tariffs are complicating the inflation data

Even as the labor market softens, tariffs are pushing certain prices higher than they otherwise would be, complicating the Federal Reserve’s effort to bring inflation down.

Government data shows that businesses have begun passing the costs of President Donald Trump’s new import tariffs to consumers. In August, clothing prices rose 0.5% and grocery prices rose 0.6%, with especially strong gains for tariff-sensitive items such as coffee.

Lower-income households are getting hit hardest because they spend more of their budget on imported goods, which tend to be the lower-cost items most affected by tariffs. A report from the Yale Budget Lab found that core goods prices are about 1.9% above pre-2025 trends as tariffs raise costs for basic items such as appliances and electronics.

Phillip Swagel, director of the Congressional Budget Office, said recently that Trump’s tariffs have pushed inflation higher than CBO analysts had expected, even as overall economic activity has weakened since January.

Typically, a slowdown in the labor market is met with slower inflation. But while the CBO now projects that the tariffs will reduce the federal budget deficit by about US$4 trillion over the next decade – roughly $3.3 trillion in new revenue and $700 billion in lower debt service costs – but it will come at the cost of near-term upward pressure on prices.

This creates a difficult balancing act for the Fed: Cut rates too quickly, and tariff-driven price pressures could reignite inflation; move too slowly, and the softening labor market could tip into recession.

A narrow path to a soft landing

As it resumes cutting rates, the Federal Reserve is trying to thread a narrow needle – easing policy enough to keep the labor market from cracking while not reigniting inflation, which is proving stickier in part because of tariffs.

Markets are betting the Fed will keep cutting. The futures market is betting the Fed will cut rates by another half point by the end of the year. And the one-year Treasury yield has dropped about 150 basis points (1.5%) since June, signaling that investors expect a series of rate cuts through 2025 and into 2026.

At its latest meeting, the Fed signaled two more rate cuts in 2025 and at least one rate cut in 2026.

Such cuts would ultimately bring the federal funds rate closer to 3% and hopefully reduce 30-year mortgage rates to around 5% – from an average of 6.35% as of Sept. 11. If the labor market continues to weaken – with jobless claims climbing, payrolls revised down and more workers stuck in long-term unemployment – that expectation will likely harden into consensus.

But the path is far from certain. Cutting rates too quickly could cause inflation to spike, while going too slow could lead to further deterioration in the labor market. Either outcome would jeopardize the Fed’s credibility – whether by appearing unable to control prices or by allowing unemployment to rise unnecessarily. That would undermine its ability to influence markets and enforce its dual mandate of maximum employment and stable prices.

Another tricky issue is Trump’s public campaign to push the Fed to cut rates – appearing to do his bidding could also undercut Fed credibility. For what it’s worth, the Sept. 17 rate cut appears driven less by politics than by economic data. The Fed itself was projecting a year ago that rates would be much lower today than they actually are, suggesting it’s been following the data.

The economy appears to be slowing but remains resilient, which is why the Fed is likely to move gradually. The risk is that the window for a soft landing is closing. The coming months will determine whether the Fed can ease early enough to avoid recession, or whether it has already waited too long.

About the Author:

Ryan Herzog, Associate Professor of Economics, Gonzaga University

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

By Jason Reed, University of Notre Dame 

The Federal Reserve is in a nearly impossible spot right now.

Markets are expecting a quarter-point interest rate cut to a range of 4% to 4.25% when the Fed policy-setting committee concludes its latest meeting on Sept. 17, 2025. After all, the slowdown in the jobs market, as well as a massive revision to past figures showing close to a million fewer jobs were created than previously reported, makes a strong case for lower interest rates to shore up the economy.

But at the same time, inflation – the other component of the Fed’s dual mandate – has begun to accelerate again. As rising tariffs squeeze consumer spending in sectors exposed to the harshest tariffs – such as clothing and electronics – other inflationary pressures loom over the horizon.

A slowing economy or rising inflation is a circumstance that policymakers want to avoid. But as an economist and finance professor, I’m increasingly concerned about the risk that they happen at the same time – a horrible economic condition known as stagflation – and that the Fed may be too slow in responding.

Between a rock and a hard data point

The Fed has been under pressure to cut rates for some time – including from President Donald Trump.

The reason markets and the White House are so interested is because what the Fed does matters. The central bank’s decision at its near-monthly meetings helps banks and other lenders to determine rates on auto loans, mortgages, credit cards and more. Lower rates usually lead more businesses and consumers to borrow and spend more, boosting economic activity. This also can drive up inflation.

For the better part of three years, the central bank has been focused on its generational fight against inflation. But now, with inflation down significantly from its 40-year high of 9% reached in 2022 and the jobs market sputtering, conditions finally seemed right to resume cutting rates.

The labor market has seen continued deterioration, most notably with the Bureau of Labor Statistics’ revisions to nonfarm payrolls – in effect reducing the number of jobs economists thought the U.S. gained by almost 1 million for the year ending in March 2025.

But a recent uptick in inflation has made the Fed’s call more complicated.

Over the past four months, the consumer price index has consistently ticked up, with the most recent CPI figure indicating year-over-year inflation of 2.9% – well above the Fed’s target of 2%.

Switching focus to jobs

At the Fed’s last meeting in August, Chair Jerome Powell said that the risks to the labor market now exceed the risks of inflation.

For example, for the first time since 2021, the number of unemployed people have outpaced job vacancies as companies have moved to eliminate open positions before laying off workers.

Most compelling is the so-called U6 unemployment rate – which includes those in the regular unemployment figures and people who have stopped looking for jobs, as well as those who are working part time but are looking for full-time opportunities. That has increased over the past three months to 8.1%.

The evidence suggests that businesses are reluctant to add workers as tariff policy and broad economic uncertainty appear to drive hiring decisions.

The worst of both worlds

The short-term risk here is that a quarter-point cut won’t be enough to shore up the jobs market, and it may be too late to prevent the economy from tipping into recession.

The longer-term risk is more concerning: Not only could the economy contract, but it could do so while inflation accelerates.

The last time the U.S. experienced stagflation was in the 1970s, when an oil embargo caused the price of crude to double. This drove up inflation while causing unemployment to soar and the economy to stall. Policies aimed at reducing inflation typically exacerbate slowing growth, and vice versa. In other words, there were fewer dollars to go around – and those dollars were worth a little less every day.

The pain experienced during this previous bout of stagflation convinced a generation of economists and policymakers that the condition was to be avoided at all costs.

The Fed, which has consistently shown its hand and has guided the markets toward this week’s rate cut, now has to make what seems like an impossible decision: cut rates even if doing so will add inflationary pressures.

And there are other potential headwinds for the U.S. economy. For example, it has yet to fully absorb the impact of Trump’s immigration crackdown on productivity and output due to the loss of workers. Waning consumer confidence suggests consumer spending could soon drop. And a potential federal government shutdown looms in September.

In my view, it’s clear that a cut is warranted. But will it drive up inflation? Economists like me will be watching this closely.

About the Author:

Jason Reed, Associate Teaching Professor of Finance, University of Notre Dame

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

By Aeimit Lakdawala, Wake Forest University 

Republican-leaning economists tend to predict stronger economic growth when a Republican is president than Democrats do – and because of this partisan optimism, their forecasts end up being less accurate.

I’m an economist, and my colleagues and I found this by analyzing nearly 40 years of responses to The Wall Street Journal’s Economic Forecasting Survey. Unlike most such surveys, the Journal publishes each forecaster’s name, allowing us to link their predictions to their political affiliations.

The respondents were professional economists at major banks, consulting firms and universities whose forecasts help guide financial markets and business decisions. Out of more than 300 economists in our sample, we could identify the political affiliations of 122. We did this by looking at the forecasters’ political donation records, voter registration data and work histories with partisan groups.

The pattern was striking: Republican forecasters systematically predicted higher gross domestic product growth when their party controlled the presidency, representing roughly 10% to 15% of average growth rates during our study period.

When we examined forecast accuracy using real-time GDP data, Republican forecasters made larger errors when their preferred party held office. This suggests partisan optimism makes their professional judgment worse.

What makes this finding particularly notable is its asymmetry. The partisan gap emerged specifically during Republican presidencies. Under Democratic Presidents Bill Clinton, Barack Obama and Joe Biden, Republican and Democratic forecasters made virtually identical predictions. That wasn’t the case when George W. Bush, and later Donald Trump, occupied the White House.

Interestingly, this bias appears only in GDP forecasts. When we analyzed predictions for inflation, unemployment and interest rates, we found no systematic differences between Republican and Democratic forecasters.

That makes sense, because GDP forecasts are inherently more uncertain than other economic predictions. Professional forecasters tend to disagree more and make more mistakes when predicting GDP compared to inflation or unemployment rates. This creates opportunities for partisan ideologies to sneak in.

We traced the bias to different views about the effectiveness of tax policies. Using Google Trends data to measure when tax cuts were in the news, we found Republican forecasters become systematically more optimistic precisely when tax policy discussions heat up.

Why it matters

Previous research has found that most people have a strong partisan bias when they make economic predictions. Our work is the first to show that professional economists can also succumb to such influences – despite their training and market incentives to be accurate.

Their errors can come at a high price. Financial markets, policymakers and businesses rely on economists’ forecasts to make major decisions. When the Federal Reserve sets interest rates, when companies plan investments and when investors allocate portfolios, they often reference these professional consensus forecasts.

Our research challenges a common assumption in economics: that aggregating diverse expert forecasts eliminates individual biases and improves accuracy.

This doesn’t mean professional forecasters are incompetent or dishonest. These are highly trained economists with strong financial incentives for accuracy. Rather, our findings reveal how even experts with the best intentions can be unconsciously influenced by their own ideological beliefs – especially when dealing with inherently uncertain data.

What still isn’t known

Several important questions remain unanswered. It’s unclear how this bias might be reduced. Would making forecasters more aware of their political leanings help reduce the effect? Or would developing new forecasting methods that weight predictions based on historical accuracy during different political regimes improve consensus forecasts?

We’re also curious whether institutional factors matter. Might forecasters at institutions with explicit political diversity policies show less bias? How do international forecasters viewing the U.S. economy compare to domestic ones?

Finally, our research focuses on U.S. forecasters during a period of increasing political polarization. Whether similar patterns emerge in other countries with different political systems, or during less polarized times, remains an open question.

The Research Brief is a short take on interesting academic work.

About the Author:

Aeimit Lakdawala, Associate Professor of Economics, Wake Forest University

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