LIGO

We use big tools to see space.

These tools find ripples in space. These ripples are called waves. They move through the dark. They come from big events in space.

One big event is when two black holes crash together. This makes a ripple. The tool uses light to find them. It uses mirrors to catch the waves.

Scientists found these waves in 2016. They saw waves from black holes. They also saw waves from stars. This was a huge discovery.

Many people work on this project. They work in the United States, Italy, and Japan. It is a big team. It helps us learn about the stars.

Scientists use big tools to study space. One such tool is LIGO. LIGO stands for Laser Interferometer Gravitational-Wave Observatory.

It looks for gravitational waves. These are ripples in space. They move through the dark. They come from big events. One event is when two black holes crash together.

LIGO uses lasers and mirrors. The mirrors are far apart. The tool measures tiny changes in length. These changes are very small. They are smaller than a tiny particle called a proton.

Scientists in the United States run LIGO. They work with teams in Italy and Japan.

LIGO found its first waves in 2016. These waves came from black holes. Later, they found waves from neutron stars. A neutron star is a very dense star.

This work won a Nobel Prize in 2017. Three scientists won the prize for their work. They helped us see the universe in a new way.

Scientists use special tools to study the deep secrets of space. One of the most important tools is called LIGO. This stands for the Laser Interferometer Gravitational-Wave Observatory.

For a long time, humans only studied the universe using light. We could see stars and planets with telescopes. We could also study particles that fly through space. But LIGO does something different and very exciting. It looks for gravitational waves, which are ripples in the fabric of space itself. These waves carry news about huge events happening far away.

LIGO works by using lasers to measure tiny changes in distance. The observatory has long arms with mirrors at the ends.

When a gravitational wave passes by, it stretches and squeezes space. This causes the distance between the mirrors to change just a tiny bit. The change is incredibly small. It is less than one ten-thousandth the size of a single proton. The lasers help scientists notice even these tiny movements. This way, the machine can "hear" the ripples from the cosmos.

Many people worked for a long time to make LIGO a reality. The idea grew from Albert Einstein's theories about how gravity works. In the 1960s, scientists like Joseph Weber began exploring these ideas. Later, Rainer Weiss from MIT published important work on using lasers for this task. Kip Thorne at Caltech also spent years studying how these waves might be found. It was not an easy path to success. The project faced many years of hard jobs and funding problems. Eventually, leaders like Barry Barish helped create a plan that worked.

LIGO is a huge project funded by the United States National Science Foundation. It has two main sites in the U.S. located in Hanford, Washington, and Livingston, Louisiana. Other observatories like Virgo in Italy and KAGRA in Japan help too. In 2017, the Nobel Prize in Physics was given to Rainer Weiss, Kip Thorne, and Barry Barish. They won for their big help in making the detector work. Since it began observing, LIGO has made hundreds of detections. These include many mergers where black holes crash into each other.

Learning about gravitational waves is like getting a new sense for the universe. Before LIGO, we could only "see" space with light. Now, we can also feel the ripples that space makes. This helps us understand things like neutron stars and black holes. A neutron star is a very dense, heavy star. When two such stars or black holes collide, they shake space. LIGO catches those shakes and tells us the story of the crash. It is a brand new way to explore the dark parts of our sky.

The Laser Interferometer Gravitational-Wave Observatory, known as LIGO, is a massive physics experiment. Its primary purpose is to detect cosmic gravitational waves. For most of human history, we studied the universe using light. We used electromagnetic radiation to see stars and planets. We also studied high-energy cosmic particles. However, gravitational waves offer a completely different way to observe space. These waves are ripples in the fabric of space itself.

LIGO uses a process called laser interferometry to find these ripples. The observatory consists of long arms with mirrors at the ends.

When a gravitational wave passes through Earth, it stretches and squeezes space. This movement causes the distance between the mirrors to change. These changes are incredibly small. The distance shift is less than one ten-thousandth the diameter of a proton. To visualize this, imagine measuring the distance to Proxima Centauri with such precision. The lasers allow scientists to measure these tiny fluctuations in length.

There are several major observatories that work together in a global network. LIGO operates two large sites in the United States. These are located in Hanford, Washington, and Livingston, Louisiana.

There are also smaller observatories in other parts of the world. The Virgo observatory is located in Italy. The KAGRA observatory is located in Japan. These different sites coordinate their observations to help confirm signals.

By working together, they create a more complete picture of the cosmos.

The history of LIGO is a long journey of scientific persistence. The concept grew from Albert Einstein's theory of general relativity. In the 1960s, scientists like Joseph Weber began exploring these ideas. In 1967, Rainer Weiss of MIT published an analysis on using interferometers. Kip Thorne at Caltech also began studying the theoretical sources of these waves. The project faced many years of difficulty. It struggled with technical issues and funding rejections in the 1980s. In 1994, Barry Barish became the laboratory director. He created a new plan that successfully secured funding from the National Science Foundation.

LIGO has moved through several distinct stages of operation. The initial LIGO observatories collected data from 2002 to 2010. However, they did not detect any gravitational waves during that time. This led to the Advanced LIGO Project to improve the detectors. These improved machines began operating in 2015. Scientists reported the first successful detection of gravitational waves in 2016. This discovery was made by the LIGO Scientific Collaboration and the Virgo Collaboration. In 2017, Weiss, Thorne, and Barish won the Nobel Prize in Physics for their work.

Observations are organized into specific periods called "runs." LIGO has completed four major observing runs so far. The first run, O1, began in September 2015. It resulted in the first three detections, which were all black hole mergers. The second run, O2, occurred from late 2016 to mid-2017. This run found seven black hole mergers and the first neutron star merger. The third run, O3, was interrupted by the COVID-19 pandemic in 2020. The fourth run, O4, began in May 2023. As of February 2026, O4 had 77 confirmed observations and 173 candidates pending analysis.

LIGO is a vital part of a much larger scientific system. It is the largest and most ambitious project ever funded by the NSF. The project involves thousands of scientists from many different universities. It also includes 440,000 active users of Einstein@Home. These users help with the massive task of analyzing data. LIGO's work connects to the study of extreme objects like black holes and neutron stars. It allows us to study the universe in ways that light cannot. This technology changes how we understand the very structure of our reality.