Lauren Blum, University of Colorado Boulder

There are trillions of charged particles – protons and electrons, the basic building blocks of matter – whizzing around above your head at any given time. These high-energy particles, which can travel at close to the speed of light, typically remain thousands of kilometers away from Earth, trapped there by the shape of Earth’s magnetic field.

Occasionally, though, an event happens that can jostle them out of place, sending electrons raining down into Earth’s atmosphere. These high-energy particles in space make up what are known as the Van Allen radiation belts, and their discovery was one of the first of the space age. A new study from my research team has found that electromagnetic waves generated by lightning can trigger these electron showers.

A brief history lesson

At the start of the space race in the 1950s, professor James Van Allen and his research team at the University of Iowa were tasked with building an experiment to fly on the United States’ very first satellite, Explorer 1. They designed sensors to study cosmic radiation, which is caused by high-energy particles originating from the Sun, the Milky Way galaxy, or beyond.

After Explorer 1 launched, though, they noticed that their instrument was detecting significantly higher levels of radiation than expected. Rather than measuring a distant source of radiation beyond our solar system, they appeared to be measuring a local and extremely intense source.

This measurement led to the discovery of the Van Allen radiation belts, two doughnut-shaped regions of high-energy electrons and ions encircling the planet.

Scientists believe that the inner radiation belt, peaking about 621 miles (1000 kilometers) from Earth, is composed of electrons and high-energy protons and is relatively stable over time.

The outer radiation belt, about three times farther away, is made up of high-energy electrons. This belt can be highly dynamic. Its location, density and energy content may vary significantly by the hour in response to solar activity.

The discovery of these high-radiation regions is not only an interesting story about the early days of the space race; it also serves as a reminder that many scientific discoveries have come about by happy accident.

It is a lesson for experimental scientists, myself included, to keep an open mind when analyzing and evaluating data. If the data doesn’t match our theories or expectations, those theories may need to be revisited.

Our curious observations

While I teach the history of the space race in a space policy course at the University of Colorado, Boulder, I rarely connect it to my own experience as a scientist researching Earth’s radiation belts. Or, at least, I didn’t until recently.

In a study led by Max Feinland, an undergraduate student in my research group, we stumbled upon some of our own unexpected observations of Earth’s radiation belts. Our findings have made us rethink our understanding of Earth’s inner radiation belt and the processes affecting it.

Originally, we set out to look for very rapid – sub-second – bursts of high-energy electrons entering the atmosphere from the outer radiation belt, where they are typically observed.

Many scientists believe that a type of electromagnetic wave known as “chorus” can knock these electrons out of position and send them toward the atmosphere. They’re called chorus waves due to their distinct chirping sound when listened to on a radio receiver.

Feinland developed an algorithm to search for these events in decades of measurements from the SAMPEX satellite. When he showed me a plot with the location of all the events he’d detected, we noticed a number of them were not where we expected. Some events mapped to the inner radiation belt rather than the outer belt.

This finding was curious for two reasons. For one, chorus waves aren’t prevalent in this region, so something else had to be shaking these electrons loose.

The other surprise was finding electrons this energetic in the inner radiation belt at all. Measurements from NASA’s Van Allen Probes mission prompted renewed interest in the inner radiation belt. Observations from the Van Allen Probes suggested that high-energy electrons are often not present in this inner radiation belt, at least not during the first few years of that mission, from 2012 to 2014.

Our observations now showed that, in fact, there are times that the inner belt contains high-energy electrons. How often this is true and under what conditions remain open questions to explore. These high-energy particles can damage spacecraft and harm humans in space, so researchers need to know when and where in space they are present to better design spacecraft.

Determining the culprit

One of the ways to disturb electrons in the inner radiation belt and kick them into Earth’s atmosphere actually begins in the atmosphere itself.

Lightning, the large electromagnetic discharges that light up the sky during thunderstorms, can actually generate electromagnetic waves known as lightning-generated whistlers.

These waves can then travel through the atmosphere out into space, where they interact with electrons in the inner radiation belt – much as chorus waves interact with electrons in the outer radiation belt.

To test whether lightning was behind our inner radiation belt detections, we looked back at the electron bursts and compared them with thunderstorm data. Some lightning activity seemed correlated with our electron events, but much of it was not.

Specifically, only lightning that occurred right after so-called geomagnetic storms resulted in the bursts of electrons we detected.

Geomagnetic storms are disturbances in the near-Earth space environment often caused by large eruptions on the Sun’s surface. This solar activity, if directed toward Earth, can produce what researchers term space weather. Space weather can result in stunning auroras, but it can also disrupt satellite and power grid operations.

We discovered that a combination of weather on Earth and weather in space produces the unique electron signatures we observed in our study. The solar activity disturbs Earth’s radiation belts and populates the inner belt with very high-energy electrons, then the lightning interacts with these electrons and creates the rapid bursts that we observed.

These results provide a nice reminder of the interconnected nature of Earth and space. They were also a welcome reminder to me of the often nonlinear process of scientific discovery.

Lauren Blum, Assistant Professor of Atmospheric and Space Physics, University of Colorado Boulder

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

Jason Reed, University of Notre Dame

If U.S. voters reelected Donald Trump hoping for relief from higher prices, his recent threats to impose tariffs on America’s three largest trade partners might make them think again.

On Saturday, Feb. 1, Trump announced 25% tariffs on Canada and Mexico and 10% tariffs on China, which he said would take effect on Tuesday, Feb. 4. While markets braced for the news to some degree, they still saw a steep premarket sell-off on Monday, Feb. 3, followed by morning volatility.

While Canada and Mexico negotiated monthlong reprieves on Monday, the new tariffs on China went into effect as expected Tuesday, Feb. 4. And while the ultimate shape of Trump’s tariff policy remains to be seen, the president warned that American consumers could feel “some pain” as a result.

Given my training as an economist and finance professor, I think Trump could be right on that score. In fact, if the tariffs go into effect, they could spell disaster for the Federal Reserve’s inflation reduction efforts.

From grocery stores to homes

U.S. consumers might be surprised to find out that almost every economic sector could be affected by this opening salvo of tariffs, should they go ahead in March. Imports from Mexico and Canada reached close to US$1 trillion in 2024, almost double the amount the U.S. imports from China.

The U.S. is particularly reliant on Mexico for fresh fruits and vegetables, and on Canada for lumber. So if the tariffs go into effect, Americans who have been waiting for home prices to ease may have to continue waiting, as tariffs on lumber and other building materials could worsen the affordable-housing crunch. And let’s not even talk about avocado prices.

Meanwhile, the 10% tariffs on Chinese goods will likely boost the price of electronics, and China has already imposed retaliatory measures. Trump has also proposed 25% tariffs on Taiwan and its semiconductor industry, in an attempt to push Taiwanese companies to invest more in U.S. manufacturing. If that tariff were to go into effect, prices for U.S. consumers would be even higher.

A tax by any other name …

Tariffs are an import tax. They’re passed through the supply chain in the form of higher prices and are eventually paid by consumers. Traditionally, governments have used tariffs as a fiscal tool to encourage businesses and consumers to move away from foreign-made products and support domestic businesses instead.

In theory, new tariffs could encourage foreign businesses to invest in the U.S. and make more stuff on American soil. Unfortunately, domestic manufacturing has seen a systemic decline since the 1980s, resulting in lower prices for consumers but severely limiting U.S.-produced products. In the short term, at least, import taxes on Canadian, Mexican and Chinese products would ultimately be paid by U.S. consumers.

Although this round of tariff threats may seem arbitrary to some, the Trump administration says it considers tariffs deeply intertwined with national security concerns. Stephen Miran, Trump’s pick to chair the president’s Council of Economic Advisers, has laid out a path for Trump’s tariff plan, which he says is aimed at putting American industry on fairer ground against the rest of the world.

In the long term, it’s unclear whether Trump’s threatened trade war will bring domestic manufacturing back to the U.S. and start a new industrial renaissance. In the meantime, American consumers will likely be stuck holding the bag.

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.

Bedassa Tadesse, University of Minnesota Duluth

On Saturday, Feb. 1, 2025, U.S. President Donald Trump announced a plan to slap steep tariffs on imports from key American trading partners – 25% on goods from Mexico and Canada and 10% on imports from China. His stated reason? To curb illegal immigration and drug trafficking.

Both Mexico and Canada managed to buy some time. After urgent phone calls with Trump on Feb. 3, their leaders each secured a one-month reprieve. But Mexico’s Claudia Sheinbaum and Canada’s Justin Trudeau also made it clear to their U.S. counterpart: If these tariffs go through, they’ll hit back with their own trade restrictions. The world is watching the opening moves of what could become another costly trade war.

As a professor of economics, I can explain why this poses significant risks to the U.S. economy and American consumers. Economic theory suggests that tariffs distort market efficiency, raising production costs while limiting consumer choice and increasing prices.

Who really pays for tariffs?

While politicians often frame tariffs as a way to punish other countries, they actually hit domestic consumers and businesses hardest. Whether they’re facing higher grocery bills or disruptions in manufacturing, Americans will feel the strain.

When tariffs are imposed, companies must either absorb the additional costs – cutting into profits and potentially threatening jobs – or pass these costs to consumers through higher prices. Small businesses operating on thin profit margins are particularly vulnerable, as many lack the resources to quickly switch suppliers.

Tariffs trigger costly retaliation

Worse yet, such measures commonly set off a cycle of retaliation. During past trade disputes involving the U.S., affected nations have responded with counter-tariffs on American products, including textiles, steel and agricultural goods. Such retaliatory efforts have led to sharp declines in U.S. exports.

During the first Trump administration, for example, China imposed retaliatory tariffs on U.S. agricultural exports. As a result, the U.S. farmers lost billions of dollars, and the U.S. spent billions in government aid to offset those losses. China has already issued new tariffs on imports of U.S. goods and export controls on some of its exports to the U.S. to retaliate for Trump’s current move.

History also shows that trade wars are self-defeating. The Smoot-Hawley Tariff Act of 1930, which imposed tariffs on over 20,000 imported goods, prompted swift retaliation from trading partners and contributed to deepening the Great Depression.

Modern trade wars have other consequences

Modern trade wars hit closer to home than most Americans realize. The recent tariff threat against Colombia reveals why. In 2023, Colombian farmers supplied US$1.14 billion worth of fresh-cut flowers to U.S. florists. In a near-crisis that lasted a weekend, Trump threatened to slap steep tariffs on the South American nation, right when flower shops across America were stocking up for one of their busiest seasons: Valentine’s Day.

The same tariffs would have hit Colombian coffee too, affecting everything from neighborhood cafes to grocery store prices. This shows how modern trade disputes can instantly disrupt the everyday purchases Americans make.

Other key trading partners, including the European Union, have also come into the crosshairs. On Jan. 30, 2025, the president issued a stark warning to Brazil, Russia, India, China and South Africa – the so-called BRICS nations – threatening 100% tariffs if they continued efforts to reduce reliance on the U.S. dollar as their reserve currency.

These threats can do more than alienate strategic partners; they risk accelerating dedollarization – pushing nations to develop alternative financial systems that weaken U.S. influence in global trade.

A more effective approach

Beyond causing immediate economic pain, constant tariff threats risk damaging America’s credibility as a reliable trading partner. The U.S. helped establish the rules-based international trading system, but regular tariff threats erode global trust and push trading partners to seek alternatives to the U.S. market.

The reality is clear: No country in the modern era has successfully used tariffs to grow its economy or improve the well-being of its people. The countries that are most dependent on tariff revenues for their national budgets are among the world’s poorest and least developed economies.

I believe the path to maintaining America’s economic leadership lies in embracing a smarter, more strategic trade policy – one that builds alliances instead of breaking them. A strategy that prioritizes negotiation, fosters innovation and enhances competitiveness – and that doesn’t rely on protectionist tactics more often used by developing nations – would strengthen cooperation and stability, ensuring long-term economic prosperity.

Bedassa Tadesse, Professor of Economics, University of Minnesota Duluth

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