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:
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.
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.
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.
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.
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 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.
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!
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.
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!
Absolutely nice round up!
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.
The GPS is more accurate using Newton’s physics. The “Einstein = Genius” makes more Noise.
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
None of those errors are Einstein. You’re just talking nonsense now.
Take any 5000 physics equations like Newton’s equation and solve in real numbers and in complex numbers and subtract the 2 solutions and plug experimental data = Einstein’s experimental numbers produced 5000 times. This method above = calculation of a visual error = Einstein. The 410 years old visual error = Earth’s motion = 27.321 days (Moon) and The Sun’s motion = 365.256 days (Earth).It’s all visual errors well established (PHD dissertation university of Michigan)
what about wormholes?
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.
… 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.
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!
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.
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.
Einstein’s experimental numbers can be produced 5000 times using any physics or any mathematics. Newton solved his equation in real numbers on in time independent domain. Solve Newton’s equation in complex numbers or time dependent domain and all of quantum physics can be produced. Subtract the two solution and get all of Einstein’s numbers. This method of solving time independent domain and time dependent domain and subtracting the 2 solutions and solutions and substituting the experimental numbers = Einstein and all of quantum or 120 years of Nobel physicists’ physics is an expression of a visual error. You being a physicist means you are mathematically deficient.
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?
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.
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.)
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?
Low risk, mind that the jets are narrow and life has survived 4 billion years. But yes, they can be nasty: https://en.wikipedia.org/wiki/Gamma-ray_burst#Rate_of_occurrence_and_potential_effects_on_life .
Interesting link. Thank you.
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.
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 ].
“Well, yeas and no” – Well, “profound implications”: yes and no.
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 ]
… “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.
So, who is following the cash flow… from Nobel prize… can’t rewrite that, just ignore!
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…
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):
In 1969 at age 11 and in 5th grade I drew real time clips of someone moving in 27.321 days (assigned to the Moon) and another moving in 365.256 days (assigned to Earth) and produced the entire solar system data time periods and orbital distances and Einstein’s experimental numbers of special and general relativity in its entirety as visual effects using 5th grade arithmetic of someone moving in 27.321 days (Earth’s actual motion wrongly assigned to the Moon) and using a time dependent frame of reference of 365.256 days (Sun’s actual motion wrongly assigned to Earth). The (27.321 days, 365.256 days) time errors = Dumb 500 years old classical physical Scientists Solar system model + 120 years of dumb f**k “Nobel” + Einstein f**ked by a 5th Grader using 5th grade arithmetic. I exterminated Einstein in 1969 and in 5th Grade.
On July 4th 1973 at age 15 and on the day after graduating from 9th grade I discovered Real Time Mathematics or the discovery that physics equations or a mathematical equation can have a time independent solution using real numbers (single solution = particle physics = Newtonian physics) and a time dependent solution using complex numbers (General solution = wave physics = quantum mechanics). The subtraction = error = visual error = relativistic = Dumb f**ks “Nobel” Scientists + Einstein f**ked by a 5th grader graduate in 1969 using 5th grate arithmetic and f**ked again in 1973 using any of 5000 physics equations or any mathematics Equation as (27.321 days, 365.256 days) error.
This is my Challenge: Any physics by any physicist from any period of time in any history can produce Einstein’s experimental numbers as visual observational errors. Meaning: Newtonian physics can produce quantum and relativistic. And if you think you are more educated than I am my reply is I am more educated than the entire human race in mathematics and physics. Physicists are mathematically deficient. How I can produce Einstein’s numbers 5000 times using any of 5000 physical sciences equations. It’s a challenge and I am in Michigan. O will meet anyone in a public place and pay got hotel for 2 days and meals for 2 days and give you named physicists mathematical whipping how to produce Einstein using any physics or any mathematics including 5th grade arithmetic
You forgot to mention the dumbing down of humanity… space has no properties! – Tesla
Extraordinary claims require extraordinary evidence… This applies to the humanities claim that “it was his wife (soon-to-be ex-wife), not Einstein, that is responsible for his seminal breakthroughs? What is the point of bringing up such claims? Is it intolerable to you that Einstein, who happened to be a male, came up with his theories without having to spit ball everything with his wife? Furthermore, what is your agenda? This is certainly not the right forum for hearsay and speculation.
To the gentleman who claims as a 5th grader you were able to outsmart Einstein, well, I don’t have much to say to you except to perhaps take some college courses on why Newtonian physics was replaced by GR. The list of examples and factuals would be too long to mention in a post, and if you are willing to have an open mind, taking a course would allow you more time to reflect on your current and long-standing mistaken beliefs. I say this in the kindest way, passing as little judgment the human brain allows. If I had a nickle for each time I’ve read that they have the true ToE’s, or that they one-upped Einstein in a certain facet of his field equations or implications from his tensor-based math, I would be a wealthy, retired person.
Thank you.Great article.I liked how ,you pointed out that if satellites was not adjusted for GPS ,it would lead you miles out of your way.