Inflatable Tower of Babel?
Pneumatic modules already used in some spacecraft could be assembled into a 15-kilometre-high towerThe team envisages assembling the structure from a series of modules constructed from Kevlar-polyethylene composite tubes made rigid by inflating them with a lightweight gas such as helium. To test the idea, they built a 7-metre scale model made up of six modules (see image). Each module was built out of three laminated polyethylene tubes 8 centimetres in diameter, mounted around circular spacers and inflated with air.
To stay upright and withstand winds, full-scale structures would require gyroscopes and active stabilisation systems in each module. The team modelled a 15-kilometre tower made up of 100 modules, each one 150 metres tall and 230 metres in diameter, built from inflatable tubes 2 metres across. Quine estimates it would weigh about 800,000 tonnes when pressurised – around twice the weight of the world’s largest supertanker.
“Twenty kilometres up is about as dark as outer space. You can see about 600 kilometres in any direction,” Quine says. Tourists could get a view almost like that from space, but without the difficulties of coping with zero gravity. He calculates the tower could be extended up to low Earth orbit at 200 kilometres.
“Beetle-juice – beetle-juice – beetle-juice!”
A 15-year, continuous observation of the red supergiant Betelgeuse has found the star, one of the largest known, is shrinking – but astronomers don’t understand why.“We don’t know what is causing the shrinking of Betelgeuse. This is part of the surprise and puzzle,” astrophysicist and Nobel laureate Charles Townes told Cosmos Online.
Betelgeuse is a red supergiant red star about 20 times as massive as the Sun. It sits in the western shoulder of the constellation Orion, and is one of the brightest stars in the sky.
Maybe it’s disappearing into the under-verse and we need to say its name three times fast?
Just when you thought you were beginning to understand the twin paradox (maybe), scientists have found something new to ponder. In the original version of the famous thought experiment on time dilation, one twin stays on Earth while the other twin takes a rocket at nearly light speed into space, and returns to find that he is younger than his twin on Earth. But a new version of the story now shows that the twin who experiences an acceleration can be older than the twin who doesn’t accelerate, under slightly different conditions.
In 1905, Einstein described the ideas behind the twin paradox to demonstrate the effects of time dilation according to special relativity. In 1911, physicist Paul Langevin turned the concept into a concrete story involving two hypothetical twins. Ever since then, scientists have offered various explanations for exactly why this aging paradox occurs, and whether it is even a true paradox at all.
As Abramowicz and Bajtlik note in their study, it is often claimed that the twin paradox can be explained by the acceleration of the traveling twin that occurs when he turns around to go back to Earth. Abramowicz and Bajtlik show, however, that it is not the acceleration that causes the age difference in most cases. By presenting a scenario in which the accelerated twin is older at the reunion, the scientists show that the final time difference between the twins often depends only on their velocities as measured with respect to an absolute standard of rest, and not on acceleration.
In the new scenario, both twins are in circular orbit at different velocities around a large body, with the velocities measured by observers rotating with zero angular momentum with respect to the sky. Abramowicz and Bajtlik considered what happens when twin A stops moving, and so has a velocity of zero, and therefore a non-zero acceleration. Twin B continues to orbit at a set velocity corresponding to Keplerian free orbit and therefore has zero acceleration. Twin A is the accelerated twin, and twin B is not accelerated. As the scientists calculate, contrary to the classical version of the paradox, twin B is younger.
Do you grok that pilgrim? It’s the final velocity, not the acceleration that does the time travel schtick.
I think they need to try this in a particle accelerator to get this right. Real experiments versus esoteric math is better science.