10 Crucial Things That Result From Einstein’s Theories of Relativity

Einstein's General Relativity Theory is Questioned

Star orbiting supermassive black hole. Credit: Nicolle Fuller/National Science Foundation

Over 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:

Entire Sky Energies Between 50 Billion and 2 Trillion Electron Volts

This image, constructed from more than six years of observations by NASA’s Fermi Gamma-ray Space Telescope, is the first to show how the entire sky appears at energies between 50 billion (GeV) and 2 trillion electron volts (TeV). For comparison, the energy of visible light falls between about 2 and 3 electron volts. Credit: NASA/DOE/Fermi LAT Collaboration

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, NASA’s 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.

Hubble Finds Smiling Face

A formation of galaxies appear to form a smiling face. Two yellow-hued blobs hang atop a sweeping arc of light. The lower, arc-shaped galaxy has the characteristic shape of a galaxy that has been gravitationally lensed — its light has passed near a massive object en route to us, causing it to become distorted and stretched out of shape. Credit: ESA/Hubble & NASA; Acknowledgment: Judy Schmidt (geckzilla)

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 NASA’s Hubble Space Telescope, the sweeping arc of light represents a distant galaxy that has been lensed, forming a “smiley face” with other galaxies.

Map of Dark Matter DES

Map of dark matter made from gravitational lensing measurements of 26 million galaxies in the Dark Energy Survey. Credit: Chihway Chang/Kavli Institute for Cosmological Physics at the University of Chicago/DES Collaboration

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 — NASA’s 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.

Gravitational Microlensing Animation

As an exoplanet passes in front of a more distant star, its gravity causes the trajectory of the starlight to bend, and in some cases, results in a brief brightening of the background star as seen by a telescope. The artistic animation illustrates this effect. This phenomenon of gravitational microlensing enables scientists to search for exoplanets that are too distant and dark to detect any other way. Credit: NASA Ames/JPL-Caltech/T. Pyle

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.”

NASA’s 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.

First Image of a Black Hole

This is the first picture of a black hole. Using the Event Horizon Telescope, scientists obtained an image of the black hole at the center of the galaxy M87. Credit: Event Horizon Telescope Collaboration

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.

Virgo A Galaxy M87

The galaxy M87, imaged here by NASA’s Spitzer Space Telescope, is home to a supermassive black hole that spews two jets of material out into space at nearly the speed of light. The inset shows a close-up view of the shockwaves created by the two jets. Credit: NASA/JPL-Caltech/IPAC

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.

Accretion Disc Surrounding Black Hole

This artist’s impression depicts the accretion disc surrounding a black hole, in which the inner region of the disc precesses. “Precession” means that the orbit of material surrounding the black hole changes orientation around the central object. Credit: ESA/ATG medialab

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 NASA’s 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.


Advanced LIGO saw gravitational waves from two black holes that merged over a billion light years from Earth. This computer simulation shows (in slow motion) what this would look like up close. If this movie were played back in real time, it would last for about one third of a second. Credit: SXS Lensing

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, NASA 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.

Cassini Saturn's Atmosphere

As depicted in this illustration, Cassini plunged into Saturn’s atmosphere on September 15, 2017. Credit: NASA/JPL-Caltech

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, NASA’s 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!

The Gravity Probe-B spacecraft

Concept of the Gravity Probe B spacecraft. A collage of images were edited to form the completed space vehicle. Credit: Katherine Stephenson, Stanford University and Lockheed Martin Corporation

10. Proof from Orbiting Earth

In 2004, NASA 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.

Global Positioning System

Global Positioning System or GPS is a United States space-based radionavigation system that helps pinpoint a three dimensional position to about a meter of accuracy (for example latitude, longitude and altitude) and provide nano-second precise time anywhere on Earth. Credit: NASA

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!

27 Comments on "10 Crucial Things That Result From Einstein’s Theories of Relativity"

  1. Torbjörn Larsson | August 29, 2020 at 4:05 pm | Reply

    Absolutely nice round up!

  2. None of the phenomina described are “because” of Einstein.

    • Of course they are BECAUSE of Einstein. They are all DIRECT consequences of general Relativity. Read a physics book before spouting rubbish. GPS wouldn’t function at all without General Relativity.

  3. It’s all wrong well established. Earth is moving in 27.321 days wrongly assigned to the Moon. The sun is moving in 365.256 days wrongly assigned to EARTH . The errors = Einstein

  4. what about wormholes?

    • Torbjörn Larsson | August 31, 2020 at 9:22 am | Reply

      Yes, what about them? The list was on observed results.

      I don’t think we have any reason to think wormholes exist any longer. The universe is on sufficiently large scales flat space, and the supernova 1987 results show that space is smooth on small scales. Inflation would have removed any pre existing gravitational defects (diluted them out of a typical observable universe).

      But mostly, if you linearize Einstein’s equations, Feynman’s path integrals describe space metric and gravity curvature separately (see Wilczek’s Core Theory) and in any case the resulting low energy effective quantum field theory predicts general relativity [ http://www.scholarpedia.org/article/Quantum_gravity_as_a_low_energy_effective_field_theory ]. So curvature geodesics of general relativity seems – to me – to be analogous to other classic field theory field lines, convenience tools but no physical existence.

  5. … relativity is kind of,… more of a detail concerned theory, as if it was developed by a woman. No, I am not saying that it was developed by a woman, I am saying that it might be developed by the woman, also known as Mileva Marić-Einstein.
    After all, if you look at her marks at the University and compare it to her husband, a well known scientist, it kind a make it strange that Albert is the one responsible for the theory, and if you know about his blunders and lack of true scientific work after she has left him…

    • Nonsense. Einstein derived bose-einstein condensates in the 1930s after leaving Mileva Maric and derived General Relativity without Mileva (she was living in Switzerland, he was in Berlin at the time). Mileva failed her final exams twice and couldn’t graduate. Einstein produced arguably 12 Nobel Prizes worth of seminal, original scientific masterpieces including his 1917 paper on spontaneous and stimulated emission which created the theoretical foundation for the LASER and began the field of condensed matter physics.

      Einstein derived the EPR Correlations I’m the 1930s, no Mileva Maric there either.

    • Torbjörn Larsson | August 31, 2020 at 9:09 am | Reply

      Please don’t try to rewrite history for your personal and/or political purposes. Using a conspiracy theory with no evidence to boot.

      Science – and culture – are too important for that!

  6. The first thing to consider is that the reason Einstein imagined time and space forming a fabric, is because from his limited perspective using only visible light telescopes, that is all it seemed is there. He was profoundly ignorant of what truly populates space from the interconnected electromagnetic structures, plasma, Heliosphere current sheet, and on and on.
    All these so called proofs are not. Light bending around a star or galaxy is due to plasma atmosphere refraction. LIGO can’t be taken seriously. Neither can the gyro experiment.
    Einstein died prior to these discoveries.

    • A Real Physicist | August 30, 2020 at 5:43 pm | Reply

      Gravitational waves are real. Einstein was right; you’re not even smart enough to understand why he was right. That’s the real tragedy. Learn done tensor calculus first.

    • Torbjörn Larsson | August 31, 2020 at 9:24 am | Reply

      Ligo and Virgo – 3 more or less independent observatories, seeing the same things – can’t be taken seriously!?

      Surely you can’t be expecting to be taken seriously. Also, why spout known pseudoscience on a science site?

  7. Mileva Maric FAILED her final exams in order to graduate TWICE. Einstein deserved 8 to 12 Nobel Prizes according to head of applied physics at Yale University Douglas Stone. Einsteins theory of General Relativity is the totality of classical physics and expresses, according to Paul Dirac “the greatest scientific discovery ever made.” Einstein, if anything, us underrated. Greatest scientist ever.

    • Torbjörn Larsson | August 31, 2020 at 9:13 am | Reply

      Newton did more heavy lifting, so did – arguably – Darwin (though in his case there were part parallel efforts, such as Wallace).

      Also, Einsteins later misguided years (working on a then fashionable “theory of everything”) is not a good merit. (But at least he wasn’t off his rocks as Eddington was.)

  8. Two photons emitted by the same colossal event, arriving nine-tenths of a second apart, after travelling for 7.3 billion years. The actual photon pulse lasted 2.1 seconds and contained many more gamma ray photons than the two mentioned.
    So, how powerful was the GRB that emitted the photons? Enough to sterilise the galaxy the event occurred in?

  9. The last item — that clocks tick at idiosyncratic rates that depend on the local gravitational field strength — has profound implications for Quantum Mechanics. In his 1964 paper, John S. Bell disregarded this easily overlooked fact, leading him to arrive at a prediction that, decades later, was found to disagree with experiment. Had Bell included the fact that time-keeping is local — varying from one location in space to the next — he would have been led to derive a different prediction that matched the predictions of QM. Entangled particles rapidly decohere for a variety of reasons, and differential time-keeping is one crucial reason that is unavoidable in our cosmos. What Einstein derided as “spooky action at a distance” turns out to be not-so-spooky time-keeping at a distance. The elusive “hidden variables” most certainly can exist, but they are necessarily time-varying. Only static traits would obey Bell’s Inequalities. Even Alain Aspect’s photons undergo gravitation red-shift/blue-shift as they traverse gravitation gradients that pervade the cosmos.

    • Torbjörn Larsson | August 31, 2020 at 9:33 am | Reply

      Well, yeas and no.

      Quantum field theory was developed as consistent with special relativity (and as I link to in another comment, seems to be able to describe general relativity as well).

      But quantum field theory plays nice with Bell test experiments – as it has to, since nature do: there are no hidden variables – and arguably entanglement is an explicit part of the theory [ https://en.wikipedia.org/wiki/Reeh%E2%80%93Schlieder_theorem ].

  10. Torbjörn Larsson | August 31, 2020 at 9:39 am | Reply

    Since I returned here I was prompted to remember some other results that I have found alluring:

    – Magnetism and the Lorentz’ force are classical and low speed relativity effects, and relativity’s universal speed limit turns up already in Maxwell’s combining electricity and magnetism as fields. (A combination that is the basis for the gauge and quantum field theories of it.)

    – The current solar system and its stability seems to be a result of relativity!

    “The main surprise that comes from the numerical simulations of the recent years is that the probability for this catastrophic events to occur is relatively high, of the order of 1%, and thus not just a mathematical curiosity with extremely low probability values. At the same time, 99% of the trajectories will behave in a similar way as in the recent past millions of years, which is coherent with our common understanding that the Solar System has not much evolved in the past 4 Gyr. What is more surprising is that if we consider a pure Newtonian world, starting with the present initial conditions, the probability of collisions within 5 Gyr grows to 60%, which can thus be considered as an additional indirect confirmation of general relativity.”

    [ http://www.scholarpedia.org/article/Stability_of_the_solar_system ]

  11. … “Thus, while some scholars have argued that there is not enough evidence to support the idea that Marić helped Einstein to develop his theories, others have argued that their letters suggest a collaboration between them, at least through 1901 before their children were born.”
    by https://en.wikipedia.org/wiki/Mileva_Mari%C4%87

    Okay, but the Universe might be a man, not a woman, due to the fact that there was more matter than antimatter…
    The God can be a woman, after all.

  12. So, who is following the cash flow… from Nobel prize… can’t rewrite that, just ignore!

  13. … So!
    What is Einstein’s standing point on the Pluto orbit, … How good is at predicting that one?
    I just could not find any data on that, strange, though…

  14. SRT is completely erroneous since it is based on the wrong kind of transformations: they have lost the scale factor characterizing the Doppler effect.
    First, Lorentz considered a more general form of transformations (with a scale factor), but then he, and also Poincare and Einstein equated it 1 without proper grounds. Their form was artificially narrowed, the formulas became incorrect. This led to a logical contradiction of the theory, to unsolvable paradoxes.
    Accordingly, GRT is also incorrect.
    For more details, see my brochure “Memoir on the Theory of Relativity and Unified Field Theory” (2000):
    http://vixra.org/abs/1802.0136

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