“The past is obdurate,” Stephen King wrote in his book about a man who goes back in time to prevent the Kennedy assassination. “It doesn’t want to be changed.”
Turns out, King might have been onto something.
Countless science fiction tales have explored the paradox of what would happen if you do something in the past that endangers the future. Perhaps one of the most famous pop culture examples is Back to the Future, when Marty McFly went back in time and accidentally stopped his parents from meeting, putting his own existence in jeopardy.
But maybe McFly wasn’t in much danger after all. According a new paper from researchers at the University of Queensland, even if time travel were possible, the paradox couldn’t actually exist.
Researchers ran the numbers, and determined that even if you make a change in the past, the timeline would essentially self-correct, ensuring that whatever happened to send you back in time would still happen.
“Say you travelled in time, in an attempt to stop COVID-19’s patient zero from being exposed to the virus,” University of Queensland scientist Fabio Costa told the university’s news service.
“However if you stopped that individual from becoming infected — that would eliminate the motivation for you to go back and stop the pandemic in the first place,” said Costa, who co-authored the paper with honors undergraduate student Germain Tobar.
“This is a paradox — an inconsistency that often leads people to think that time travel cannot occur in our universe.”
A variation is known as the “grandfather paradox” — in which a time traveler kills their own grandfather, in the process preventing the time traveler’s birth.
The logical paradox has given researchers a headache, in part because according to Einstein’s theory of general relativity, “closed time-like curves” are possible, theoretically allowing an observer to travel back in time and interact with their past self — and potentially endangering their own existence.
But these researchers say that such a paradox wouldn’t necessarily exist, because events would adjust themselves.
Take the coronavirus patient zero example. “You might try and stop patient zero from becoming infected, but in doing so you would catch the virus and become patient zero, or someone else would,” Tobar told the university’s news service.
In other words, a time traveler could make changes — but the original outcome would still find a way to happen. Maybe not the same way it happened in the first timeline; but close enough so that the time traveler would still exist, and would still be motivated to go back in time.
“No matter what you did, the salient events would just recalibrate around you,” Tobar said.
The paper, “Reversible dynamics with closed time-like curves and freedom of choice,” was published last week in the peer-reviewed journal Classical and Quantum Gravity. The findings seem consistent with another time travel study published this summer in the peer-reviewed journal Physical Review Letters. That study found that changes made in the past won’t drastically alter the future.
Best-selling science fiction author Blake Crouch, who has written extensively about time travel, said the new study seems to support what certain time travel tropes have posited all along.
“The universe is deterministic and attempts to alter Past Event X are destined to be the forces which bring Past Event X into being,” Crouch told NPR via email. “So the future can affect the past. Or maybe time is just an illusion. But I guess it’s cool that the math checks out.”
SpaceX launches 60 more satellites during 15th Starlink mission – Yahoo Lifestyle UK
<p class="canvas-atom canvas-text Mb(1.0em) Mb(0)–sm Mt(0.8em)–sm" type="text" content="This launch used a Falcon 9 first stage booster that twice previously, both times earlier this year, including just in September for the delivery of a prior batch of Starlink satellites. The booster was also recovered successfully with a landing at sea aboard SpaceX’s ‘Just Read the Instructions’ floating autonomous landing ship in the Atlantic Ocean.” data-reactid=”20″>This launch used a Falcon 9 first stage booster that twice previously, both times earlier this year, including just in September for the delivery of a prior batch of Starlink satellites. The booster was also recovered successfully with a landing at sea aboard SpaceX’s ‘Just Read the Instructions’ floating autonomous landing ship in the Atlantic Ocean.
Earlier this week, Ector County Independent School District in Texas announced itself as a new pilot partner for SpaceX’s Starlink network. Next year, that district will gain connectivity to low latency broadband via Starlink’s network, connecting up to 45 households at first, with plans to expand it to 90 total household customers as more of the constellation is launched and brought online.
SpaceX’s goal with Starlink is to provide broadband service globally at speeds and with latency previously unavailable in hard-to-reach and rural areas. Its large constellation, which will aim to grow to tens of thousands of satellites before it achieves its max target coverage, offers big advantages in terms of latency and reliability vs. large geosynchronous satellites that provide most current satellite-based internet available commercially.
SpaceX adds another 60 satellites to Starlink network – Spaceflight Now – Spaceflight Now
SpaceX successfully deployed 60 more Starlink internet satellites in orbit Saturday, continuing a record launch cadence while engineers assess a concern with Falcon 9 rocket engines that has delayed other missions, including the next crew flight to the International Space Station.
The 60 Starlink satellites blasted off from pad 40 at Cape Canaveral Air Force Station at 11:31:34 a.m. EDT (1531:34 GMT) Saturday. The mission was delayed from Thursday to allow time for engineers to assess a problem with a camera on the Falcon 9 rocket’s upper stage.
Nine kerosene-fueled Merlin 1D engines powered the 229-foot-tall (70-meter) launcher into the sky on a trajectory northeast from Cape Canaveral.
The rocket’s first stage shut down its engines and separated two-and-a-half minutes into the mission, beginning a controlled descent to a pinpoint landing on a floating platform parked some 400 miles (630 kilometers) northeast of the launch site.
The landing concluded the third trip to space and back for the reusable Falcon 9 booster — designated B1060 — and the touchdown occurred moments before the rocket’s upper stage delivered the 60 Starlink satellites into a preliminary parking orbit.
SpaceX did not try to catch the Falcon 9’s two-piece payload fairing as they fell back to Earth under parachutes. A nose cone structure damaged a net on one of SpaceX’s fairing recovery vessels on the company’s most recent launch Oct. 18.
Instead, SpaceX dispatched one of the boats from its fleet to retrieve the fairing structures from the Atlantic Ocean for inspections, refurbishment, and potential use on a future flight.
After coasting across the Atlantic Ocean, Europe and the Middle East, the Falcon 9’s upper stage briefly reignited its single engine at T+plus 44 minutes to inject the Starlink satellites into a near-circular orbit at an altitude of roughly 170 miles (275 kilometers) with an inclination of 53 degrees to the equator.
All 60 satellites, which were flat-packed on top of the Falcon 9 rocket for launch, separated from the upper stage at 12:34 p.m. EDT (1634 GMT). A live video feed from the rocket showed the flat-panel satellites receding from view as they flew south of Tasmania.
SpaceX’s Falcon 9 rocket lifted off from Cape Canaveral at 11:31am EDT (1531 GMT) with 60 more Starlink internet satellites, darting through clouds in an autumn sky on the way to orbit.
— Spaceflight Now (@SpaceflightNow) October 24, 2020
The satellites, built by SpaceX in Redmond, Washington, were expected to unfurl power-generating solar arrays and prime their krypton ion thrusters to begin raising their orbits to an operational altitude of 341 miles (550 kilometers), where they will join more than 800 other Starlink relay stations to beam broadband internet signals across most of the populated world.
SpaceX plans to operate an initial block of around 1,500 Starlink satellites in orbits 341 miles above Earth. The company, founded by billionaire Elon Musk, has regulatory approval from the Federal Communications Commission to eventually field a fleet of up to 12,000 small Starlink broadband stations operating in Ku-band, Ka-band, and V-band frequencies.
There are also preliminary plans for an even larger fleet of 30,000 additional Starlink satellites, but a network of that size has not been authorized by the FCC.
SpaceX says the Starlink network — designed for low-latency internet service — is still in its early stages, and engineers continue testing the system to collect latency data and speed tests. In a filing with the FCC dated Oct. 13, SpaceX said it has started beta testing of the Starlink network in multiple U.S. states, and is providing internet connectivity to previously unserved students in rural areas.
On Sept. 28, the Washington Military Department announced it was using the Starlink internet service as emergency responders and residents in Malden, Washington, recover from a wildfire that destroyed much of the town.
Earlier this month, Washington government officials said the Hoh Tribe was starting to use the Starlink service. SpaceX said it recently installed Starlink ground terminals on an administrative building and about 20 private homes on the Hoh Tribe Reservation.
A catalog of Starlink satellites maintained by Jonathan McDowell, a widely-respected astronomer who tracks global spaceflight activity, indicated that 53 of the Starlink satellites have been deorbited since their launch, primarily test models that launched last year. Two other satellites have failed and another 20 appear have stopped maneuvering, leaving around 820 spacecraft presumably operational, according to McDowell.
Since Oct. 6, SpaceX has shot 180 Starlink satellites into orbit on three dedicated Falcon 9 rocket missions. That’s more satellites than in the entire constellation operated by Planet, which owns the second-biggest fleet of spacecraft in orbit.
As of this week, Planet had around 150 active SkySat and Dove Earth-imaging satellites in its fleet, a company spokesperson said.
SpaceX continues Starlink launches while engine issue delays other missions
The launch of three Starlink missions on Falcon 9 rockets this month occurred as SpaceX delayed other launches to study an issue with Merlin engines that aborted a Falcon 9 countdown Oct. 2 with a U.S. military GPS navigation satellite.
Elon Musk, SpaceX’s founder and CEO, tweeted after the abort that the countdown was stopped at T-minus 2 seconds after an “unexpected pressure rise in the turbomachinery gas generator,” referring to equipment used on the rocket’s nine Merlin first stage main engines. The gas generators on the Merlin 1D engines drives the engines’ turbopumps.
NASA announced Oct. 10 that the launch from the Kennedy Space Center of SpaceX’s first operational Crew Dragon flight to the International Space Station would be delayed from Oct. 31 until early to mid-November to allow time for engineers to study and resolve the engine issue.
Kathy Lueders, head of NASA’s human spaceflight programs, tweeted Oct. 21 that the space agency and SpaceX were making “a lot of good progress … on engine testing to better understand the unexpected behavior observed during a recent non-NASA launch.”
It’s too early to report findings at this point, as SpaceX continues testing to validate what’s believed to be the most credible cause,” Lueders tweeted.
She wrote that SpaceX is replacing one engine on the Falcon 9 rocket assigned to the Crew Dragon mission — known as Crew-1 — and one engine on the Falcon 9 booster designated for launch of a U.S.-European oceanography satellite next month from Vandenberg Air Force Base, California.
The engines being replaced displayed behavior during their ground testing that was similar to the “early-start behavior” noted during the aborted GPS launch Oct. 2., Lueders wrote.
The launch of the Sentinel-6 Michael Freilich oceanography satellite remains scheduled for Nov. 10 from California, Lueders said.
“We are also still working towards a mid-November launch for Crew-1,” she added. “We will want a few days between Sentinel-6 and Crew-1 to complete data reviews and check performance. Most importantly, we will fly all our missions when we are ready.”
The Crew-1 mission will launch four astronauts to begin a six-month expedition on the International Space Station. It follows a two-man Crew Dragon test flight that launched May 30 and concluded with a successful return to Earth on Aug. 2, the first orbital flight of astronauts to launch from U.S. soil since the retirement of the space shuttle in 2011.
In a press briefing Oct. 16, a NASA manager said engineers from NASA, the U.S. Space Force, and SpaceX are jointly investigating the engine problem that surfaced during the Oct. 2 countdown.
“I can tell you an incredible amount of data has been looked at, to include members from our commercial crew program which also has an upcoming Falcon flight,” said Tim Dunn, NASA’s launch director for the Sentinel-6 Michael Freilich mission.
In addition to testing at the launch base at Cape Canaveral, SpaceX removed engines from the Falcon 9 rocket for the GPS mission and returned them to the company’s test facility in McGregor, Texas, for detailed testing and reviews.
“We’ve learned a lot,” Dunn said. “There’s going to be some hardware implications as we move forward, depending on the engines installed on various rockets. The GPS mission obviously is affected. The NASA Crew-1 mission is affected. On Sentinel-6, we are looking at the engines that are on our first stage. We are going to work through what we need to do, but as of today, we have a path forward that allows us to do whatever necessary rework may be required and still maintain that Nov. 10 launch date.”
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NASA spacecraft leaking asteroid samples into space is 'victim of own success' – Euronews
A NASA spacecraft has been so successful in grabbing rubble from an asteroid hurtling through space millions of miles from Earth, that it collected too much and is now spilling its precious cargo back into the void.
In the space agency’s first attempt at taking samples from an asteroid, the spacecraft Osiris-Rex briefly touched asteroid Bennu earlier this week.
But scientists now know it collected far more material than was expected, and its sample container is jammed open.
“We’re almost a victim of our own success here,” said the mission’s lead scientist, Dante Lauretta of the University of Arizona.
Lauretta said there is nothing flight controllers can do to clear the obstructions and prevent more bits of Bennu from escaping, other than to get the samples into their return capsule as soon as possible.
The flight team was scrambling to put the sample container into the capsule as early as Tuesday – much sooner than originally planned – for the long trip home.
Scientists were shocked on Thursday when they saw the pictures coming from Osiris-Rex following its contact with Bennu two days earlier.
A cloud of asteroid particles could be seen swirling around the spacecraft as it backed away from the asteroid.
The situation appeared to stabilise, according to Lauretta, once the robot arm was locked into place but it was impossible to know exactly how much material had already been lost.
The requirement for the mission was to bring back a minimum of 2 ounces (60 grams).
Because of the sudden turn of events, scientists won’t know how much the sample capsule is holding until it’s back on Earth.
The samples won’t make it back until 2023 – seven years after the spacecraft took off.
The complicated €675 million mission, which started with a launch back in 2016, is expected to provide information about the building blocks of the solar system.
They initially planned to spin the spacecraft to measure the contents, but that manoeuvre was cancelled since it could spill even more debris.
Japan, meanwhile, is awaiting its second batch of samples taken from a different asteroid, due back in December.
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