*KR: This is virtual science where nothing is certain and yet this modern science, calls the old science a myth. *
*xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx* *Einstein’s Theory of General Relativity Was Game-Changing, But It’s Still Inherently Flawed* More than 100 years after Albert Einstein theorized an explanation for the force governing space and time, scientists are still trying to solve mysteries of black holes and the quantum universe. *BY **SARAH WELLS* <https://www.popularmechanics.com/author/227695/Sarah-Wells/>PUBLISHED: DEC 20, 2022 - General relativity <https://www.popularmechanics.com/space/deep-space/a32172691/black-hole-orbiting-star-einstein-general-relativity/> principles govern both the very small and the most vast objects in our universe, but not the quantum world. - Gravity <https://www.popularmechanics.com/space/deep-space/a27011/esa-green-light-lisa-mission/> may not be a force like the other physical forces, but a result of spacetime’s curvature. - Physicists are still exploring many mysteries, such as why black holes <https://www.popularmechanics.com/space/deep-space/a42136486/closest-black-hole-to-earth-discovered/> have a singularity at their center. ------------------------------ >From smashing particles together to analyzing the properties of a supermassive black hole <https://www.popularmechanics.com/space/deep-space/a41612520/black-hole-burps-up-star/>, much of physics research takes place far beyond the realm of our everyday experience. However, there is one hallmark of physics that even a crawling baby can intuitively understand: gravity <https://www.popularmechanics.com/science/a34873839/black-holes-fuzzballs-string-theory/> . The effects of this force are both small (working against a baby as they learn to walk) and vast (controlling the movements of cosmic bodies, like Earth, through their invisible orbits in space <https://www.popularmechanics.com/space/a39679658/lagrange-points-james-webb-space-telescope/>). Apart from our own experiences, our first formal introduction to gravity is typically through Newton’s lens, which describes gravity as both: - a constant force on Earth (little g) equal to 9.8 meters squared - gravity beyond Earth’s bounds with Newton’s gravitational constant (big G) While this understanding generally works fine for everyday life, it’s far from the whole story. Just shy of 200 years after Newton’s death, Einstein would publish a new theory of gravity in 1915 called the theory of general relativity. It would transform our understanding of physics forever.“According to Einstein, gravity is then not an ‘instantaneous force,’ like Newton had predicted, but rather a manifestation of the curvature of spacetime,” he says. *General vs. Special Relativity* One important point to clarify before digging into the meat of general relativity is that Einstein actually proposed *two* famous theories of relativity. Ten years before putting the ideas of general relativity down to paper, he penned a theory called special relativity <https://www.popularmechanics.com/science/environment/a29210217/missing-phase-of-matter/> . Einstein predicted that massive objects in space, like planets or even black holes, would act like cosmic bowling balls and pull down the fabric of spacetime ... this curvature itself is gravity. Elena Giorgi <http://www.math.columbia.edu/~egiorgi/> is an assistant professor of mathematics at the University of Columbia whose research has a special focus on general relativity. She explains to *Popular Mechanics* that a major difference between the two theories is that special relativity “only considers small objects moving in an empty spacetime, while in general relativity, massive objects such as stars or galaxies <https://www.popularmechanics.com/space/deep-space/a32109712/how-many-galaxies/> are allowed.” In other words, special relativity lays out important ideas such as the speed of light <https://www.popularmechanics.com/science/a41473994/how-light-travels/> being the same for all observers, and the laws of physics <https://www.popularmechanics.com/science/a38539247/universe-evolves-laws-of-physics-by-itself/> holding true regardless of reference frame (e.g. on Earth or in a speeding rocket ship). Meanwhile, general relativity introduced super heavy objects and gravity to the party. “General relativity says that space and time <https://www.popularmechanics.com/science/a41106690/grandfather-paradox-time-travel/> form a unified continuum, and this continuum can be distorted, curved, stretched when in the presence of matter,” Yunes says. A simple way to picture this is imagining what would happen if you placed a bowling ball onto a flat mattress. Intuitively, we can expect that the heavy object would sink into the mattress and cause the area around it to curve down. Einstein predicted that massive objects in space, like planets or even black holes, would act like cosmic bowling balls and pull down the fabric of spacetime. Instead of an outside force creating gravity, the theory of general relativity shows that this curvature* itself* is gravity <https://www.popularmechanics.com/science/energy/a40241329/gravity-energy/>. This idea may seem impossible given our own experiences of gravity, but for more than 100 years scientists have been seeing its repercussions play out in space. “From the first observations of light deflection during an eclipse, to the most recent detection of gravitational waves <https://www.popularmechanics.com/space/deep-space/a41118858/gravitational-waves-invisible-universe/>, every observation we make seems to be consistent with the predictions of general relativity,” Yunes says. “At least, so far.” In addition to detecting gravitational waves—ripples in spacetime <https://www.popularmechanics.com/space/deep-space/a35795047/traversable-wormholes-could-exist-in-real-world/> created when there’s a massive collision in space—the effects of general relativity can also be used to help scientists see further into space through something called gravitational lensing. In a nutshell, the gravity well created by a heavy object like a star works to slingshot distant light around it, making it possible for astronomers to detect light that would’ve been too far away before. *What We Still Don’t Know* While general relativity is yet to be disproven, there are still questions about the theory that haven’t been resolved. For example, whether or not black holes actually have a singularity at their center, Yunes says, or whether or not general relativity can be applied to the early universe, Giorgi says. A singularity <https://www.livescience.com/what-is-singularity> represents a situation in which our current understanding of physical laws breaks down. For example, at the center of a black hole, the gravity is so great that matter apparently would have zero volume <https://www.popularmechanics.com/science/a41926325/how-to-measure-volume/>, which is not possible. So some piece of our understanding is still missing. Another shortcoming of Einstein’s theory of general relativity is that while it seems to do a very good job at explaining the gravity of extremely large things, it cannot be applied to the extremely small domain of the quantum <https://www.popularmechanics.com/science/a40898392/quantum-physics-consciousness/> world. On the level of subatomic particles <https://www.popularmechanics.com/science/a41031157/protons-contain-charm-quarks/>, the effect of gravity is practically negligible compared to other forces like electromagnetism, the weak nuclear forces <https://www.popularmechanics.com/science/a40753268/understanding-the-standard-model/>, and the strong nuclear forces. - Are Wormholes Real or Science Fiction? <https://www.popularmechanics.com/space/deep-space/a41978813/what-is-a-wormhole/> - Scientists Discover Closest Black Hole to Earth <https://www.popularmechanics.com/space/deep-space/a42136486/closest-black-hole-to-earth-discovered/> - Aliens Could Send Us Quantum Messages From Space <https://www.popularmechanics.com/science/a40604228/aliens-could-send-quantum-messages-from-space/> Unifying these two worlds with one single theory is a huge dream for physicists, but so far no one has managed to find one. As for continuing to test general relativity in its own domain, Giorgi says that continuing to study black holes and gravitational waves with increasing sensitivity will continue to help test the boundaries of this theory. “Many aspects of the detection of gravitational waves emitted by the merger of two black holes is only understood with a certain approximation, leaving space for further improvements,” she says. “[Including] the future plan of having [LIGO-like] interferometers in space which will be even more precise.” LIGO <https://www.ligo.caltech.edu/page/what-is-ligo> is a Laser Interferometer Gravitational-wave Observatory, and it’s the world’s largest, having detected dozens of sources of gravitational waves, including from ten pairs of black holes merging and two pairs of colliding neutron stars <https://www.popularmechanics.com/space/deep-space/a30444347/ligo-neutron-stars/> . Sarah is a science and technology journalist based in Boston interested in how innovation and research intersect with our daily lives. She has written for a number of national publications and covers innovation news at *Inverse*. KR IRS 24222 -- You received this message because you are subscribed to the Google Groups "Thatha_Patty" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/thatha_patty/CAL5XZooy%3DAYjJ3wmMLyoZx0Y3F%3DmUd_93_UL0YyE6btY3nL%3DeA%40mail.gmail.com.
