Tag Archives: astrophysics

Is the universe a hologram?

Wrap your head around this on a Monday morning, if you can: what we think of as the three dimensional universe we inhabit may in fact just be a holographic projection, and Craig Hogan is trying to prove it [via BigThink and Ian Sales].

The idea that spacetime may not be entirely smooth – like a digital image that becomes increasingly pixelated as you zoom in – had been previously proposed by Stephen Hawking and others. Possible evidence for this model appeared last year in the unaccountable “noise” plaguing the GEO600 experiment in Germany, which searches for gravitational waves from black holes. To Hogan, the jitteriness suggested that the experiment had stumbled upon the lower limit of the spacetime pixels’ resolution.

Black hole physics, in which space and time become compressed, provides a basis for math showing that the third dimension may not exist at all. In this two-dimensional cartoon of a universe, what we perceive as a third dimension would actually be a projection of time intertwined with depth. If this is true, the illusion can only be maintained until equipment becomes sensitive enough to find its limits.

“You can’t perceive it because nothing ever travels faster than light,” says Hogan. “This holographic view is how the universe would look if you sat on a photon.”

Coming soon to a Greg Egan short story collection near you…

I just never get tired of these existential cosmology ideas. As I’ve said before, this is the sort of stuff that makes me wish I’d actually paid attention at university and gone on to study hardcore physics… though given how much I sucked at calculus, it’s probably best that I didn’t.

Are we alone?

saucersTranshumanist blogger George Dvorsky points to a debate between astrophysicist Brandon Carter and a team of Serbian researchers, the core of which revolves around how long complex (and intelligent) life takes to evolve:

Prior to ‘recent times’, universal mechanisms were in place to continually thwart the evolutionary development of intelligence, namely through gamma-ray bursts, super novae and other forms of nastiness. Occasional catastrophic events have been resetting the “astrobiological clock” of regions of the Galaxy causing biospheres to start over. “Earth may be rare in time, not in space,” they say. They also note that the rate of evolution is intimately connected with a planet’s environment, such as the kind of radiation its star emits.

For further discussion of our place in the universe see the Copernican Principle, which exhorts us to avoid assuming that humanity, Earth, and our place in the universe can be assumed to be unique and special.

Further the notion of punctuated equilibrium to describe evolution is interesting: might it be extended to describe other evolutionary phenomena? Eric Beinhocker‘s superb The Origin of Wealth describes both technology and the economy in terms of evolutionary systems, both of which experience a form of punctuated equilibrium.

[image from eek the cat on flickr]

Direct evidence of dark matter detected over Antarctica?

antarctic balloon A high-altitude balloon experiment above the Antarctic may have just seen a possible signature of the mysterious “dark matter” thought to make up 85 percent of the mass of the universe–but as yet, completely unseen and not at all completely understood. (Via Nature News.)

The experiment, the Advanced Thin Ionization Calorimeter (ATIC), spotted a surplus of high-energy electrons coming from…somewhere. This matches something the PAMELA (Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics–don’t you love space-exploration acronyms?) satellite mission turned up earlier this year

Electrons at this particular energy could be the result of heavy dark-matter particles colliding, which according to Dan Hooper, a theoretical physicist at Fermi National Accelerator Laboratory, is “certainly the sexiest of the possibilities.”

Sexy and, to non-physicists, more than a little weird:

The exact nature of the dark-matter particles that produce electrons is uncertain, but one idea is that they may be ordinary particles that spend part of their lives in a compact extra dimension of space. Whereas the particles would appear relatively stationary to observers trapped in three spatial dimensions, they could be moving at ultra-high speeds in a fourth spatial dimension. At high speeds, they would create a gravitational force that could be felt by matter trapped in three dimensions of space-time. “It’s very wild,” Hooper says.

I’ll drink to that!

Of course, there are other possibilities. In particular, the electrons could be coming from a nearby pulsar, the fast-spinning remnants of a supernova.

How do we figure out? More experiments, of course. A new orbiting telescope called Fermi can spot electrons and positrons (though it’s designed to hunt for high-energy X-rays), and thus may confirm the data, or even pick up other high-energy particles that could be produced by dark-matter collisions.

Check back in the spring.

(Photo: NASA.)

[tags]NASA,dark matter,astrophysics,balloons[/tags]

‘Flux transfer events’ connect Earth and Sun

News to me:

Like giant, cosmic chutes between the Earth and sun, magnetic portals open up every eight minutes or so to connect our planet with its host star.

Once the portals open, loads of high-energy particles can travel the 93 million miles (150 million km) through the conduit during its brief opening, space scientists say.

Called a flux transfer event, or FTE, such cosmic connections not only exist but are possibly twice as common as anyone ever imagined, according to space scientists who attended the 2008 Plasma Workshop in Huntsville, Ala., last week.

Ten years ago I was pretty sure they didn’t exist, but now the evidence is incontrovertible,” said David Sibeck, an astrophysicist at the Goddard Space Flight Center in Maryland.

There must be a use for these things, in fiction or real life…

[Image: NASA]