relativity

If you asked an astrophysicist what is yet to be discovered in the universe, there’s a good chance they’d paraphrase Donald Rumsfeld: It’s full of known unknowns. What Drew Noomi Rapace to Constellation?Besides the regular matter and energy we know and love, the universe is also composed of two big mysteries: dark energy and dark matter. Theoretical astrophysicists aim to tackle these unknowns by mathematically dreaming up objects that could address the gaps in our knowledge. Thus, in research published in Classical and…

According to findings by physicists at Goethe University Frankfurt, a gravastar could look like a matryoshka doll. Credit: Daniel Jampolski and Luciano Rezzolla, Goethe University Frankfurt, editedPhysicists at Goethe University Frankfurt find new solution to Einstein’s general theory of relativity.If gravitational condensate stars (or gravastars) actually existed, they would look similar to black holes to a distant observer. Two theoretical physicists at Goethe University Frankfurt have now found a new solution to Albert…

Orbital observatories such as the Hubble Space Telescope and James Webb Space Telescope (JWST) can see far back into the universe—so far, in fact, that they have revealed some of the earliest galaxies to form in the first 500 million years of our universe’s 13.8-billion-year-history. Much further back, we can see the remnant heat left over from the big bang, the cosmic microwave background (CMB) radiation, which was emitted about 400,000 years into cosmic history. But what about the period after the CMB appeared and…

Albert Einstein was one smart cookie; there's no doubt about it. But even he knew his general theory of relativity – the 21st century's answer to Newton's universal theory of gravity – wasn't perfect.Like the second-hand car you bought using your first paycheck, it does the job for day-to-day errands. Push it too hard up a steep hill or park it near a quantum strip mall, and that engine shudders to a standstill.Peoples' Friendship University of Russia astrophysics grad student Hamidreza Fazlollahi's solution is to dive…

An artist’s impression of the system assuming that the massive companion star is a black hole. The brightest background star is its orbital companion, the radio pulsar PSR J0514-4002E. The two stars are separated by 8 million km and circle each other every 7 days. Credit: Daniëlle Futselaar (artsource.nl)Using the MeerKAT Telescope, astronomers found a mysterious object in the Milky Way’s black hole mass gap, challenging existing astronomical classifications and offering a unique opportunity to study the universe’s most…

The Geometry Task (an adapted and expanded version of a task from Beckmann, 2005). Credit: Cognition and Instruction (2023). DOI: 10.1080/07370008.2023.2293695 Although a typical mathematical task has a single correct answer, in some cases, the assumptions of a proposition determine its truth. Such relativity of truth plays a major role in the development of mathematics. Furthermore, in our…

While Interstellar popularised the idea of black holes, physicists and research labs continue to expand their research of such interstellar phenomena to further understand the origins of our universe. In December 2021, the US-based National Aeronautics Space Agency launched the imaging X-ray polarimetry explorer mission to explore the remnants of supernova explosions, the particle streams emitted by black holes and other cosmic events.  On 1 January,…

The general theory of relativity (or general relativity for short) is a major building block of modern physics. It explains gravity based on the way space can 'curve', or, to put it more accurately, it associates the force of gravity with the changing geometry of space-time.History of general relativityAlbert Einstein settled on his 'general' theory in 1915, a decade after he came up with a 'special' theory of relativity that applied a universal speed of light to the assumption that the laws of physics stay the same…

Can we turn back time? Ask a savvy physicist, and the answer will be “it depends.”Schemes for retrograde time travel abound but usually involve irreconcilable paradoxes and rely on outlandish theoretical constructs such as wormholes (which may not actually exist). Yet when it comes to simply turning back the clock—akin to stirring a scrambled raw egg and seeing the yolk and white reseparate—a rich and growing subfield of wave physics shows that such “time reversal” is possible.Reversing time would seem to fundamentally…

A new theory challenges the foundations of modern physics by suggesting that spacetime is classical, not quantum. This theory predicts larger spacetime fluctuations, impacting object weights. Proposed experiments, like measuring a 1kg mass for weight fluctuations, aim to test this groundbreaking concept, potentially revolutionizing our understanding of gravity and spacetime. A radical theory that consistently unifies gravity and quantum mechanics while preserving Einstein’s classical concept of spacetime is announced…