Showing all posts about science

You can travel no further back in time than 1955

18 August 2009

The Time Traveler’s Wife is the latest in a long line of time travel themed movies, and according to physicist Dave Goldberg, makes for a more realistic representation of time travel than most of the (fiction) served to date.

But this is interesting, time travel is (theoretically) only possible to points in time where a time machine already exists, according to Goldberg.

In other words, for Marty McFly to travel from 1985 to back to 1955, as he did in Back to the Future, a DeLorean like time machine would already need to have been in existence in 1955…

According to Einstein’s picture of the universe, space and time are curved and very closely related to each other. This means that traveling through time would be much like traveling through a tunnel in space — in which case you’d need both an entrance and an exit. As a time traveler, you can’t visit an era unless there’s already a time machine when you get there — an off-ramp. This helps explain why we’re not visited by time-traveling tourists from our own future. Futuristic humans don’t drop in for dinner because we haven’t yet invented time travel.

Of course the concept of time travel — in the form of the Flux Capacitor — did exist in 1955, it simply hadn’t taken physical form… does that count?

Originally published Tuesday 18 August 2009, with subsequent revisions, updates to lapsed URLs, etc.

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Detecting and defending Earth from asteroids, other threats

29 September 2008

The Association of Space Explorers (ASE) is calling on the United Nations (UN) to co-ordinate efforts to defend Earth from “potentially catastrophic asteroid threats“.

The report asks the UN to assume responsibility for responding to potentially catastrophic asteroid threats. “For 4.5 billion years, we’ve been bashed continuously by asteroids. It’s time for that to stop,” former Apollo 9 astronaut Rusty Schweickart told the assembly. The ASE’s vision is first for a global information network, coordinated by the UN, that uses data from ground- and space-based telescopes to find, track and rate the risk of near-Earth objects (NEOs).

Originally published Monday 29 September 2008, with subsequent revisions, updates to lapsed URLs, etc.

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Uneven heat emission sending Pioneers 10 and 11 off course

7 July 2008

The mystery surrounding the unexplained course deviations of deep space probes Pioneers 10 and 11, which are currently somewhere in the vicinity of the Solar System’s Kuiper Belt, may have been solved. At least partly, that is.

Slava Turyshev, of NASA’s Jet Propulsion Laboratory, has spent the last two years studying data from the probes, which were launched in the 1970s, and concluded that uneven heat build-up across their structures is causing the trajectory anomalies:

Pioneer 11 gives off heat in certain directions more than others. The uneven heat emission is enough to nudge the spacecraft off course, accounting for 28% to 36% of the anomaly detected when Pioneer 11 was 3750 million kilometres, or 25 times the Earth-sun distance, away from us.

Originally published Monday 7 July 2008.

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Pioneers 10 and 11 courses inexplicably varying at Kuiper Belt

15 September 2004

Something weird is happening out on the boundary of our solar system, an area called the Kuiper Belt, where NASA space probes Pioneers 10 and 11 are presently located.

Both deep space probes, launched over thirty years ago, traversed the inner region of the solar system almost exactly according to plan.

Since passing beyond the orbit of Pluto though, events have taken an unexpected turn: both probes appear to be inexplicably deviating from their projected courses.

And no one can work out why. Some scientists think long held ideas on the effects of gravity over extended distances may be need to be re-thought. Others say that both probes may be leaking gases, which is contributing to the change in their trajectories.

This mystery has led to calls for a new deep space mission to see what’s happening out at the Kuiper.

By fitting a Pioneer follow-up probe with new measuring equipment, navigational device and communications gear, it should be possible to discover if the probes are in the grip of a new force of nature.

A new force of nature? Perhaps Star Wars director George Lucas’ far, far, away galaxy may not be all that distant after all…

Originally published Wednesday 15 September 2004.

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Hal, of 2001: A Space Odyssey fame, inducted into Robot Hall of Fame

16 November 2003

I didn’t realise that Hal, AKA HAL 9000, the supercomputer in Stanley Kurbick’s 1968 film, 2001: A Space Odyssey, was regarded as a robot, but apparently he is. That’s why Hal was, recently, inducted into the Robot Hall of Fame.

There he joins other illustrious bots and ‘droids, including R2D2 from, of course, Star Wars. This hall of renown, brought to us by Carnegie Mellon University’s School of Computer Science, is not restricted to fictional robots though, as the Mars Sojourner Rover is also honoured with a place.

Originally published Sunday 16 November 2003, with subsequent revisions, updates to lapsed URLs, etc.

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The Big Bang might have been big, but it sounded like a hum

31 October 2003

Judging by the amount of press it generates, it seems we just love talking about the Big Bang, the theory that explains the existence of the universe. And why not? We wouldn’t be here now talking about it, if it er, hadn’t have happened. Theoretically speaking that is.

The latest revelations published in New Scientist suggest the Big Bang was more of a deep hum rather than an explosive, booming, bang. Whether it was a bang or a hum though, there’s no doubting its volume, which was certainly loud.

Another news service carrying the same story compared the noise levels as being similar to a jet aeroplane with its engines operating at full power just ten or so metres above your house.

A little like the noise that Concorde used to create perhaps? Theoretically speaking that is .

Originally published Friday 31 October 2003, with subsequent revisions, updates to lapsed URLs, etc.

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