June 29, 2020
Enjoy these interesting stories from the scientific community.
*-- Space tourists might rise above Earth with hydrogen balloons --*
The newest entry into a growing field of space tourism firms says it will use giant hydrogen balloons launched from Kennedy Space Center in Florida -- rather than rockets -- to give passengers a view of the stars from the stratosphere.
At 20 miles up, Space Perspective's observation capsule would reach about one-third of the way to outer space, but passengers could see the blackness above and observe the curvature of the Earth.
The company, which signed an agreement to use NASA facilities, has potential to boost the growing space tourism sector that includes Elon Musk's SpaceX and Jeff Bezos' Blue Origin.
But the new startup's founders said they have funding only to mount a maiden uncrewed test flight, scheduled for early 2021, with the potential for more if that is successful.
"We're designing this to have a very low training requirement, with little more training than a passenger on a commercial jet, to make it as accessible as possible," said Jane Poynter, co-founder and co-CEO with her husband, Taber MacCallum.
Tickets would cost roughly $125,000, Poynter said. By comparison, tickets for Richard Branson's Virgin Galactic are estimated to cost $250,000 for a brief rocket flight 50 miles high. But no space tourism flights have left the ground yet.
Space Perspectives' plan calls for a balloon -- large enough to accommodate a football field inside -- to be sent aloft from the former space shuttle runway.
The capsule beneath, called Neptune, would be 16 feet wide, with an interior to fit nine seats and a restroom.
A parachute would deploy in the event of a problem with the balloon, but the capsule would not have thrusters to steer it. Rather, it would drift with the wind, making monitoring weather forecasts crucial to ensure safety.
"We are confident we can accurately predict where it will go and have recovery ships waiting," MacCallum said.
At 12 mph, the capsule would take two hours to reach cruising level, where it would drift for hours and then descend slowly to a splashdown in the Atlantic Ocean.
Space Perspectives, whose funding rounds were led by a Silicon Valley venture capital firm Base Ventures, rents offices at the space center for a small amount, according to Dale Ketcham of Space Florida, the state agency that arranges commercial leases for NASA.
Poynter and MacCallum previously led a what started out as a space tourism company, World View, which used balloons. But it eventually turned to science and transportation payloads instead of carrying people.
The couple also worked with Alan Eustace, a Google executive who used a balloon to set a world record for the highest parachute dive in 2014.
Employing hydrogen balloons to carry passengers, though, will undoubtedly raise memories of the Hindenburg fire and explosion that killed 36 people in 1937, said Jim Cantrell, a space businessman who helped found SpaceX.
"I don't like the idea of using hydrogen myself," Cantrell said. "You're probably more likely to get killed on one of our freeways than with something like this, but it will require a change in perspective."
Poynter and MacCallum have widespread respect in the space community, though, Cantrell said.
"We just don't know about the success of space tourism in the long run because it hasn't been done. We do know people are lining up to pay deposits on Virgin Galactic tickets," he said.
Poynter and MacCallum's track record suggests they will succeed, said John Spencer, an outer space architect who worked on the International Space Station design.
"There's no issue, in terms of physics or money, that they can't overcome," said Spencer, who heads the non-profit Space Tourism Society, whose mission is to build interest in the sector.
"They are pioneering a whole new regime of space exploration," Spencer said. "The only question is if another big player comes in and beats them to it."
*-- Scientists confirm 50-year-old theory that aliens could exploit a black hole for energy --*
 Lab experiments have confirmed the 50-year-old theory that an alien civilization could exploit a black hole for energy.
More than a half-century ago, British physicist Roger Penrose surmised that energy could be harvested from a black hole by dropping an object into it's ergosphere, the outer layer of the black hole's event horizon.
The object would need to be quickly split in two, allowing half to fall into the black hole and the other half recovered. According to Penrose's theory, the recoil action would provide the recovered half of the object a loss of negative energy. It would, in effect, gain energy.
Not just any aliens could carry out such a complex engineering feat, Penrose acknowledged. If aliens were to harvest energy from a black hole, they'd need to be highly advanced.
In 1971, two years after Penrose published his theory, another physicist, Yakov Zel'dovich, claimed the idea could be put to the test on Earth using twisted light waves bounced off the surface of a cylinder spun at just the right speed. Zel'dovich claimed a phenomenon known as the rotational doppler effect would cause the reflected light waves to bounce back with surplus energy.
Zel'dovich's proposal has gone untested, in part due to the need for the cylinder to rotate at speeds in excess of a billion revolutions per second -- a technological impossibility.
To finally put Penrose's original theory to the test, researchers at the University of Glasgow, in Scotland, developed an alternative experiment using sound waves instead of light waves. By using waves with lower frequencies, the test wouldn't require the cylinder to spin so fast.
Researchers at the University of Glasgow's School of Physics and Astronomy set up a unique combination of speakers to create a twist in the sound waves. Scientists directed the twisting sound waves toward a foam disc. Behind the disk, the team positioned a microphone.
Instead of bouncing off the foam disk, the sound waves traveled through and were picked up by the microphone on the other side. Recordings of the altered sound waves revealed changes in frequency and amplitude consistent with the doppler effect predicted by Zel'dovich.
Researchers detailed the results of their experiment this week in the journal Nature Physics.
"The linear version of the doppler effect is familiar to most people as the phenomenon that occurs as the pitch of an ambulance siren appears to rise as it approaches the listener but drops as it heads away," lead study author Marion Cromb, a doctoral student at Glasgow, said in a news release. "It appears to rise because the sound waves are reaching the listener more frequently as the ambulance nears, then less frequently as it passes."
"The rotational doppler effect is similar, but the effect is confined to a circular space," Cromb said. "The twisted sound waves change their pitch when measured from the point of view of the rotating surface. If the surface rotates fast enough then the sound frequency can do something very strange -- it can go from a positive frequency to a negative one, and in doing so steal some energy from the rotation of the surface."
When researchers accelerated the spin of the foam disk, the sound from the speakers quieted, becoming too low to hear. As the disk spun faster, the pitch got higher and higher until it returned to its original pitch -- only louder, with an amplitude 30 percent greater than before.
"What we heard during our experiment was extraordinary. What's happening is that the frequency of the sound waves is being doppler-shifted to zero as the spin speed increases. When the sound starts back up again, it's because the waves have been shifted from a positive frequency to a negative frequency," Cromb said. "Those negative-frequency waves are capable of taking some of the energy from the spinning foam disc, becoming louder in the process -- just as Zel'dovich proposed in 1971."
Researchers suggest their surprise discovery has paved the way for a variety of new physics experiments. Scientists hope their test can be replicated using electromagnetic waves or some other kind of waves.
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