Breaking the Warp Barrier for Faster-Than-Light Travelhttps://phys.org/news/2021-03-warp-barrier-faster-than-light.html
If travel to distant stars within an individual's lifetime is going to be possible, a means of faster-than-light propulsion will have to be found. To date, even recent research about superluminal (faster-than-light) transport based on Einstein's theory of general relativity would require vast amounts of hypothetical particles and states of matter that have 'exotic' physical properties such as negative energy density. This type of matter either cannot currently be found or cannot be manufactured in viable quantities. In contrast, new research carried out at the University of Göttingen gets around this problem by constructing a new class of hyper-fast 'solitons' using sources with only positive energies that can enable travel at any speed. This reignites debate about the possibility of faster-than-light travel based on conventional physics. The research is published in the journal
Classical and Quantum Gravity.The author of the paper, Dr. Erik Lentz, analyzed existing research and discovered gaps in previous 'warp drive' studies. Lentz noticed that there existed yet-to-be explored configurations of space-time curvature organized into 'solitons' that have the potential to solve the puzzle while being physically viable.
A soliton—in this context also informally referred to as a 'warp bubble'—is a compact wave that maintains its shape and moves at constant velocity. Lentz derived the Einstein equations for unexplored soliton configurations (where the space-time metric's shift vector components obey a hyperbolic relation), finding that the altered space-time geometries could be formed in a way that worked even with conventional energy sources. In essence, the new method uses the very structure of space and time arranged in a soliton to provide a solution to faster-than-light travel, which—unlike other research—would only need sources with positive energy densities. No exotic negative energy densities needed.
If sufficient energy could be generated, the equations used in this research would allow space travel to Proxima Centauri, our nearest star, and back to Earth in years instead of decades or millennia. That means an individual could travel there and back within their lifetime. In comparison, the current rocket technology would take more than 50,000 years for a one-way journey. In addition, the solitons (warp bubbles) were configured to contain a region with minimal tidal forces such that the passing of time inside the soliton matches the time outside: an ideal environment for a spacecraft. This means there would not be the complications of the so-called 'twin paradox' whereby one twin traveling near the speed of light would age much more slowly than the other twin who stayed on Earth: in fact, according to the recent equations both twins would be the same age when reunited.
"This work has moved the problem of faster-than-light travel one step away from theoretical research in fundamental physics and closer to engineering. The next step is to figure out how to bring down the astronomical amount of energy needed to within the range of today's technologies, such as a large modern nuclear fission power plant. Then we can talk about building the first prototypes," says Lentz.
Erik W Lentz,
Breaking the warp barrier: hyper-fast solitons in Einstein–Maxwell-plasma theory,
Classical and Quantum Gravity (2021)
https://iopscience.iop.org/article/10.1088/1361-6382/abe692 -------------------------------------------
Microscopic Wormholes Possible In Theoryhttps://phys.org/news/2021-03-microscopic-wormholes-theory.htmlWormholes play a key role in many science fiction films—often as a shortcut between two distant points in space. In physics, however, these tunnels in spacetime have remained purely hypothetical. An international team led by Dr. Jose Luis Blázquez-Salcedo of the University of Oldenburg has now presented a new theoretical model in the science journal
Physical Review Letters that makes microscopic wormholes seem less far-fetched than in previous theories.
... Previous models suggest that the only way to keep the wormhole open is with an exotic form of matter that has a negative mass, or in other words weighs less than nothing, and which only exists in theory. However, Blázquez-Salcedo and his colleagues Dr. Christian Knoll from the University of Oldenburg and Eugen Radu from the Universidade de Aveiro in Portugal demonstrate in their model that wormholes could also be traversable without such matter.
The researchers chose a comparatively simple "semiclassical" approach. They combined elements of relativity theory with elements of quantum theory and classic electrodynamics theory. In their model they consider certain elementary particles such as electrons and their electric charge as the matter that is to pass through the wormhole. As a mathematical description, they chose the Dirac equation, a formula that describes the probability density function of a particle according to quantum theory and relativity as a so-called Dirac field.
As the physicists report in their study, it is the inclusion of the Dirac field into their model that permits the existence of a wormhole traversable by matter, provided that the ratio between the electric charge and the mass of the wormhole exceeds a certain limit. In addition to matter, signals—for example electromagnetic waves—could also traverse the tiny tunnels in spacetime.
Jose Luis Blázquez-Salcedo et al,
Traversable Wormholes in Einstein-Dirac-Maxwell Theory,
Physical Review Letters (2021)
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.126.101102 ------------------------------------------
Flight through a Wormholehttps://www.spacetimetravel.org/wurmlochflug/wurmlochflug.html------------------------------------------
360° Traversing a flat Worm Hole
