10 Things Einstein Got Right

One hundred years ago, on May 29, 1919, astronomers observed a total solar eclipse in an ambitious effort to test Albert Einstein’s general theory of relativity by seeing it in action. Essentially, Einstein thought space and time were intertwined in an infinite “fabric,” like an outstretched blanket. A massive object such as the Sun bends the spacetime blanket with its gravity, such that light no longer travels in a straight line as it passes by the Sun.

This means the apparent positions of background stars seen close to the Sun in the sky – including during a solar eclipse – should seem slightly shifted in the absence of the Sun, because the Sun’s gravity bends light. But until the eclipse experiment, no one was able to test Einstein’s theory of general relativity, as no one could see stars near the Sun in the daytime otherwise.

The world celebrated the results of this eclipse experiment— a victory for Einstein, and the dawning of a new era of our understanding of the universe.

General relativity has many important consequences for what we see in the cosmos and how we make discoveries in deep space today. The same is true for Einstein's slightly older theory, special relativity, with its widely celebrated equation E=mc². Here are 10 things that result from Einstein’s theories of relativity:

1. Universal Speed Limit

Einstein's famous equation E=mc² contains "c," the speed of light in a vacuum. Although light comes in many flavors – from the rainbow of colors humans can see to the radio waves that transmit spacecraft data – Einstein said all light must obey the speed limit of 186,000 miles (300,000 kilometers) per second. So, even if two particles of light carry very different amounts of energy, they will travel at the same speed.

This has been shown experimentally in space. In 2009, our Fermi Gamma-ray Space Telescope detected two photons at virtually the same moment, with one carrying a million times more energy than the other. They both came from a high-energy region near the collision of two neutron stars about 7 billion years ago. A neutron star is the highly dense remnant of a star that has exploded. While other theories posited that space-time itself has a "foamy" texture that might slow down more energetic particles, Fermi's observations found in favor of Einstein.

2. Strong Lensing

Just like the Sun bends the light from distant stars that pass close to it, a massive object like a galaxy distorts the light from another object that is much farther away. In some cases, this phenomenon can actually help us unveil new galaxies. We say that the closer object acts like a “lens,” acting like a telescope that reveals the more distant object. Entire clusters of galaxies can be lensed and act as lenses, too.

When the lensing object appears close enough to the more distant object in the sky, we actually see multiple images of that faraway object. In 1979, scientists first observed a double image of a quasar, a very bright object at the center of a galaxy that involves a supermassive black hole feeding off a disk of inflowing gas. These apparent copies of the distant object change in brightness if the original object is changing, but not all at once, because of how space itself is bent by the foreground object’s gravity.

Sometimes, when a distant celestial object is precisely aligned with another object, we see light bent into an “Einstein ring” or arc. In this image from our Hubble Space Telescope, the sweeping arc of light represents a distant galaxy that has been lensed, forming a “smiley face” with other galaxies.

3. Weak Lensing

When a massive object acts as a lens for a farther object, but the objects are not specially aligned with respect to our view, only one image of the distant object is projected. This happens much more often. The closer object’s gravity makes the background object look larger and more stretched than it really is. This is called “weak lensing.”

Weak lensing is very important for studying some of the biggest mysteries of the universe: dark matter and dark energy. Dark matter is an invisible material that only interacts with regular matter through gravity, and holds together entire galaxies and groups of galaxies like a cosmic glue. Dark energy behaves like the opposite of gravity, making objects recede from each other. Three upcoming observatories -- Our Wide Field Infrared Survey Telescope, WFIRST, mission, the European-led Euclid space mission with NASA participation, and the ground-based Large Synoptic Survey Telescope --- will be key players in this effort. By surveying distortions of weakly lensed galaxies across the universe, scientists can characterize the effects of these persistently puzzling phenomena.

Gravitational lensing in general will also enable NASA’s James Webb Space telescope to look for some of the very first stars and galaxies of the universe.

4. Microlensing

So far, we’ve been talking about giant objects acting like magnifying lenses for other giant objects. But stars can also “lens” other stars, including stars that have planets around them. When light from a background star gets “lensed” by a closer star in the foreground, there is an increase in the background star’s brightness. If that foreground star also has a planet orbiting it, then telescopes can detect an extra bump in the background star’s light, caused by the orbiting planet. This technique for finding exoplanets, which are planets around stars other than our own, is called “microlensing.”

Our Spitzer Space Telescope, in collaboration with ground-based observatories, found an “iceball” planet through microlensing. While microlensing has so far found less than 100 confirmed planets, WFIRST could find more than 1,000 new exoplanets using this technique.

5. Black Holes

The very existence of black holes, extremely dense objects from which no light can escape, is a prediction of general relativity. They represent the most extreme distortions of the fabric of space-time, and are especially famous for how their immense gravity affects light in weird ways that only Einstein’s theory could explain.

In 2019 the Event Horizon Telescope international collaboration, supported by the National Science Foundation and other partners, unveiled the first image of a black hole’s event horizon, the border that defines a black hole’s “point of no return” for nearby material. NASA's Chandra X-ray Observatory, Nuclear Spectroscopic Telescope Array (NuSTAR), Neil Gehrels Swift Observatory, and Fermi Gamma-ray Space Telescope all looked at the same black hole in a coordinated effort, and researchers are still analyzing the results.

6. Relativistic Jets

This Spitzer image shows the galaxy Messier 87 (M87) in infrared light, which has a supermassive black hole at its center. Around the black hole is a disk of extremely hot gas, as well as two jets of material shooting out in opposite directions. One of the jets, visible on the right of the image, is pointing almost exactly toward Earth. Its enhanced brightness is due to the emission of light from particles traveling toward the observer at near the speed of light, an effect called “relativistic beaming.” By contrast, the other jet is invisible at all wavelengths because it is traveling away from the observer near the speed of light. The details of how such jets work are still mysterious, and scientists will continue studying black holes for more clues.

7. A Gravitational Vortex

Speaking of black holes, their gravity is so intense that they make infalling material “wobble” around them. Like a spoon stirring honey, where honey is the space around a black hole, the black hole’s distortion of space has a wobbling effect on material orbiting the black hole. Until recently, this was only theoretical. But in 2016, an international team of scientists using European Space Agency's XMM-Newton and our Nuclear Spectroscopic Telescope Array (NUSTAR) announced they had observed the signature of wobbling matter for the first time. Scientists will continue studying these odd effects of black holes to further probe Einstein’s ideas firsthand.

Incidentally, this wobbling of material around a black hole is similar to how Einstein explained Mercury’s odd orbit. As the closest planet to the Sun, Mercury feels the most gravitational tug from the Sun, and so its orbit’s orientation is slowly rotating around the Sun, creating a wobble.

8. Gravitational Waves

Ripples through space-time called gravitational waves were hypothesized by Einstein about 100 years ago, but not actually observed until recently. In 2016, an international collaboration of astronomers working with the Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors announced a landmark discovery: This enormous experiment detected the subtle signal of gravitational waves that had been traveling for 1.3 billion years after two black holes merged in a cataclysmic event. This opened a brand new door in an area of science called multi-messenger astronomy, in which both gravitational waves and light can be studied.

For example, our telescopes collaborated to measure light from two neutron stars merging after LIGO detected gravitational wave signals from the event, as announced in 2017. Given that gravitational waves from this event were detected mere 1.7 seconds before gamma rays from the merger, after both traveled 140 million light-years, scientists concluded Einstein was right about something else: gravitational waves and light waves travel at the same speed.

9. The Sun Delaying Radio Signals

Planetary exploration spacecraft have also shown Einstein to be right about general relativity. Because spacecraft communicate with Earth using light, in the form of radio waves, they present great opportunities to see whether the gravity of a massive object like the Sun changes light’s path.

In 1970, our Jet Propulsion Laboratory announced that Mariner VI and VII, which completed flybys of Mars in 1969, had conducted experiments using radio signals — and also agreed with Einstein. Using NASA’s Deep Space Network (DSN), the two Mariners took several hundred radio measurements for this purpose. Researchers measured the time it took for radio signals to travel from the DSN dish in Goldstone, California, to the spacecraft and back. As Einstein would have predicted, there was a delay in the total roundtrip time because of the Sun’s gravity. For Mariner VI, the maximum delay was 204 microseconds, which, while far less than a single second, aligned almost exactly with what Einstein’s theory would anticipate.

In 1979, the Viking landers performed an even more accurate experiment along these lines. Then, in 2003 a group of scientists used NASA’s Cassini Spacecraft to repeat these kinds of radio science experiments with 50 times greater precision than Viking. It’s clear that Einstein’s theory has held up!

10. Proof from Orbiting Earth

In 2004, we launched a spacecraft called Gravity Probe B specifically designed to watch Einstein’s theory play out in the orbit of Earth. The theory goes that Earth, a rotating body, should be pulling the fabric of space-time around it as it spins, in addition to distorting light with its gravity.

The spacecraft had four gyroscopes and pointed at the star IM Pegasi while orbiting Earth over the poles. In this experiment, if Einstein had been wrong, these gyroscopes would have always pointed in the same direction. But in 2011, scientists announced they had observed tiny changes in the gyroscopes’ directions as a consequence of Earth, because of its gravity, dragging space-time around it.

BONUS: Your GPS! Speaking of time delays, the GPS (global positioning system) on your phone or in your car relies on Einstein’s theories for accuracy. In order to know where you are, you need a receiver – like your phone, a ground station and a network of satellites orbiting Earth to send and receive signals. But according to general relativity, because of Earth’s gravity curving spacetime, satellites experience time moving slightly faster than on Earth. At the same time, special relativity would say time moves slower for objects that move much faster than others.

When scientists worked out the net effect of these forces, they found that the satellites’ clocks would always be a tiny bit ahead of clocks on Earth. While the difference per day is a matter of millionths of a second, that change really adds up. If GPS didn’t have relativity built into its technology, your phone would guide you miles out of your way!

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Space Missions Come Together in Colorado

Our leadership hit the road to visit our commercial partners Lockheed Martin, Sierra Nevada Corp. and Ball Aerospace in Colorado. They were able to check the status of flight hardware, mission operations and even test virtual reality simulations that help these companies build spacecraft parts.

Let’s take a look at all the cool technology they got to see…

Lockheed Martin

Lockheed Martin is the prime contractor building our Orion crew vehicle, the only spacecraft designed to take humans into deep space farther than they’ve ever gone before.

Acting NASA Deputy Administrator Lesa Roe and Acting NASA Administrator Robert Lightfoot are seen inside the CHIL…the Collaborative Human Immersive Laboratory at Lockheed Martin Space Systems in Littleton, Colo. Lockheed Martin’s CHIL enables collaboration between spacecraft design and manufacturing teams before physically producing hardware.

Cool shades! The ability to visualize engineering designs in virtual reality offers tremendous savings in time and money compared to using physical prototypes. Technicians can practice how to assemble and install components, the shop floor can validate tooling and work platform designs, and engineers can visualize performance characteristics like thermal, stress and aerodynamics, just like they are looking at the real thing.

This heat shield, which was used as a test article for the Mars Curiosity Rover, will now be used as the flight heat shield for the Mars 2020 rover mission.

Fun fact: Lockheed Martin has built every Mars heat shield and aeroshell for us since the Viking missions in 1976.

Here you can see Lockheed Martin’s Mission Support Area. Engineers in this room support six of our robotic planetary spacecraft: Mars Odyssey, Mars Reconnaissance Orbiter, MAVEN, Juno, OSIRIS-REx and Spitzer, which recently revealed the first known system of seven Earth-size planets around a single star, TRAPPIST-1. They work with NASA centers and the mission science teams to develop and send commands and monitor the health of the spacecraft.

See all the pictures from the Lockheed Martin visit HERE.

Sierra Nevada Corporation

Next, Lightfoot and Roe went to Sierra Nevada Corporation in Louisville, Colo. to get an update about its Dream Chaser vehicle. This spacecraft will take cargo to and from the International Space Station as part of our commercial cargo program.

Here, Sierra Nevada Corporation’s Vice President of Space Exploration Systems Steve Lindsey (who is also a former test pilot and astronaut!) speaks with Lightfoot and Roe about the Dream Chaser Space System simulator.

Lightfoot climbed inside the Dream Chaser simulator where he “flew” the crew version of the spacecraft to a safe landing. This mock-up facility enables approach-and-landing simulations as well as other real-life situations.

See all the images from the Sierra Nevada visit HERE.

Ball Aerospace

Lightfoot and Roe went over to Ball Aerospace to tour its facility. Ball is another one of our commercial aerospace partners and helps builds instruments that are on NASA spacecraft throughout the universe, including the Hubble Space Telescope and the New Horizons mission to Pluto. Ball designed and built the advanced optical technology and lightweight mirror system that will enable the James Webb Space Telescope to look 13.5 billion years back in time.

Looking into the clean room at Ball Aerospace’s facility in Boulder, Colo., the team can see the Ozone Mapping Profiler Suite. These sensors are used on spacecraft to track ozone measurements.

Here, the group stands in front of a thermal vacuum chamber used to test satellite optics. The Operation Land Imager-2 is being built for Landsat 9, a collaboration between NASA and the U.S. Geological Survey that will continue the Landsat Program’s 40-year data record monitoring the Earth’s landscapes from space.

See all the pictures from the Ball Aerospace visit HERE.

We recently marked a decade since a new era began in commercial spaceflight development for low-Earth orbit transportation. We inked agreements in 2006 to develop rockets and spacecraft capable of carrying cargo such as experiments and supplies to and from the International Space Station. Learn more about commercial space HERE.

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8 years ago

Are you scared about going up into space?

I’m not scared, but I have a healthy amount of nervousness because I don’t know exactly what to expect. I have a lot of great advice, but you don’t know until you actually get there.

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6 years ago

Global Temperature by the Numbers

The Year

4th Hottest

2018 was the fourth hottest year since modern recordkeeping began. NASA and the National Oceanic and Atmospheric Administration work together to track temperatures around the world and study how they change from year to year. For decades, the overall global temperature has been increasing.

Over the long term, world temperatures are warming, but each individual year is affected by things like El Niño ocean patterns and specific weather events.

1.5 degrees

Globally, Earth’s temperature was more than 1.5 degrees Fahrenheit warmer than the average from 1951 to 1980.

The Record

139 years

Since 1880, we can put together a consistent record of temperatures around the planet and see that it was much colder in the late-19th century. Before 1880, uncertainties in tracking global temperatures were too large. Temperatures have increased even faster since the 1970s, the result of increasing greenhouse gases in the atmosphere.

Five Hottest

The last five years have been the hottest in the modern record.

6,300 Individual Observations

Scientists from NASA use data from 6,300 weather stations and Antarctic research stations, together with ship- and buoy-based observations of sea surface temperatures to track global temperatures.

The Consequences

605,830 swimming pools

As the planet warms, polar ice is melting at an accelerated rate. The Greenland and Antarctic ice sheets lost about 605,830 Olympic swimming pools (400 billion gallons) of water between 1993 and 2016.

8 inches

Melting ice raises sea levels around the world. While ice melts into the ocean, heat also causes the water to expand. Since 1880, sea levels around the world have risen approximately 8 inches.

71,189 acres burned

One symptom of the warmer climate is that fire seasons burn hotter and longer. In 2018, wildfires burned more than 71,189 acres in the U.S. alone.

46% increase in CO2 levels

CO2 levels have increased 46 percent since the late 19th Century, which is a dominant factor causing global warming.

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8 years ago

Jessica, first of all, I love you. Second, what's it like being a part of the first class that was 50% female?

Thank you! The best part is that I think the fact that our class is 50% female simply reflects how far our society has come, and that is a great thing! To us, there really is no difference on whether or not we are female or male, what backgrounds we come from, etc., we are one team, one family, all contributing to the same cause (which is an extraordinary feeling!). I’m definitely very proud and honored to be part of the 21st astronaut class.

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3 years ago

What does “chemical fingerprints” mean? What chemicals indicate possible life on other planets?

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1 year ago

Hi do you guys really say Houston when responding to each other !?!🤪

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9 years ago

Vision & Microgravity...Can We See the Connection?

What do nutrition and genetics have in common? They could all be linked to vision problems experienced by some astronauts. We see people going up to space with perfect vision, but need glasses when the return home to Earth.

Why Does This Study Matter?

We want to be able to send astronauts to Mars, but losing vision capability along the way is a BIG problem. Discovering the cause and possible treatments or preventions will help us safely send astronauts deeper into space than ever before.

It’s Like Solving a Mystery

We already have an idea of why vision changes occur, but the real mystery remains...why do some astronauts have these issues, and other’s don’t?

Now, let’s break it down:

Nutrition is more than just what you eat. It includes how those things work inside your body. The biochemistry behind how your muscles make energy, how your brain utilizes glucose and how vitamins help with biochemical functions...it’s all part of nutrition.

Genetics also play a part in the vision changes we’re seeing in space. Data shows that there are differences in blood chemistry between astronauts that had vision issues and those that did not. We found that individuals with vision issues had different blood chemistries even before their flight to space. That means that some astronauts could be predisposed to vision issues in space.

Just in January 2016, scientists discovered this possible link between genetics, nutrition and vision changes in astronauts. It makes it clear that the vision problem is WAY more complex than we initially thought.

While we still don’t know exactly what is causing the vision issues, we are able to narrow down who to study, and refine our research. This will help find the cause, and hopefully lead to treatment and prevention of these problems.

Fluid Shifts

The weightless environment of space also causes fluid shifts to occur in the body. This normal shift of fluids to the upper body in space causes increased inter-cranial pressure which could be reducing visual capacity in astronauts. We are currently testing how this can be counteracted by returning fluids to the lower body using a “lower body negative pressure” suit, also known as Chibis.

Benefits on Earth

Research in this area has also suggested that there may be similarities between astronaut data and individuals with a clinical syndrome affecting 10-20% of women, known as polycystic ovary syndrome. Studying this group may provide a way to better understand vision and cardiovascular system effects, which could also advance treatment and prevention for both astronauts and humans on Earth with this disease.

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6 years ago

@paleskeletonuniversitypizza: How does it feel to experience weightlessness for the first time?

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6 years ago

This is no Westeros. On April 8, 2019, the Landsat 8 satellite acquired a scene of contrasts in Russia: a fire surrounded by ice.

Between chunks of frozen land and lakes in the Magadan Oblast district of Siberia, a fire burned and billowed smoke plumes that were visible from space.

Not much is known about the cause of the fire, east of the town of Evensk. Forest fires are common in this heavily forested region, and the season usually starts in April or May. Farmers also burn old crops to clear fields and replenish the soil with nutrients, also known as ‘slash and burn agriculture’; such fires occasionally burn out of control. Land cover maps, however, show that this fire region is mainly comprised of shrublands, not croplands.

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9 years ago

7 Sports Astronauts Love Without Gravity (Including Football)

Astronauts onboard the International Space Station spend most of their time doing science, exercising and maintaining the station. But they still have time to shoot hoops and toss around a football.

From chess to soccer, there’s a zero-gravity spin to everything.

1. Baseball

Baseball: America’s favorite pastime. JAXA astronaut, Satoshi Furukawa shows us how microgravity makes it possible to be a one-man team. It would be a lot harder to hit home runs if the players could jump that high to catch the ball.

2. Chess

Yes, it’s a sport, and one time NASA astronaut Greg Chamitoff (right) played Earth on a Velcro chess board. An elementary school chess team would pick moves that everyone could vote for online. The winning move would be Earth’s play, and then Chamitoff would respond. About every two days, a move would be made. But who won the historic Earth vs. Space match? Earth! Chamitoff resigned after Earth turned its pawn into a queen, but it was game well played.

3. Soccer

NASA astronaut Steve Swanson put a new spin on soccer by juggling the ball upside down. However, he might not have considered himself upside down. On the space station, up and down are relative.

4. Gymnastics

NASA astronauts usually sign off their videos with a zero-gravity somersault (either forwards or backwards). But astronauts are also proficient in handstands, flips and twists. The predecessor to the International Space Station, the Skylab, had the best space for the moves. The current space station is a bit tight in comparison.

5. Basketball

Objects that aren’t heavy don’t move very well on the space station. They kind of just float. It’s like Earth, but exaggerated. For example, on Earth a beach ball wouldn’t go as far as a basketball. The same is true in space, which is why playing with a basketball in space is more fun than playing with a beach ball.

6. Golf

People talk about hitting golf balls off skyscrapers, but what about off the International Space Station? While golf isn’t a normal occurrence on the station, it’s been there. One golf company even sent an experiment to the station to find out how to make better golf clubs.

7. Football

Zero gravity doesn’t make everything easier. Astronauts need to relearn how to throw things because their brains need to relearn how to interpret sensory information. A bowling ball on the space station no longer feels as heavy as a bowling ball on Earth. When astronauts first throw things on the space station, everything keeps going too high. That would put a wrench in your spiral for a couple of months. But once you adjust, the perfect spiral will just keep spiraling!

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