Posted on by Ian O'Neill

The “Astronomical Unit” May Need an Upgrade as the Sun Loses Mass

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The Sun is constantly losing mass. Our closest star is shedding material through the solar wind, coronal mass ejections and by simply generating light. As the burning giant begins a new solar cycle, it continues to lose about 6 billion kilograms (that’s approximately 16 Empire State Building’s worth) of mass per second. This may seem like a lot, but when compared with the total mass of the Sun (of nearly 2×1030 kilograms), this rate of mass loss is miniscule. However small the mass loss, the mass of the Sun is not constant. So, when using the Astronomical Unit (AU), problems will begin to surface in astronomical calculations as this “universal constant” is based on the mass of the Sun…

The AU is commonly used to describe distances within the Solar System. For instance, one AU is approximately the mean distance from the Sun to Earth orbit (defined as 149,597,870.691 kilometres). Mars has an average orbit of 1.5AU, Mercury has an average of about 0.4AU… But how is the distance of one AU defined? Most commonly thought to be derived as the mean distance of the Sun-Earth orbit, it is actually officially defined as: the radius of an unperturbed circular orbit that a massless body would revolve about the Sun in 2Ï€/k days (that’s one year). There lies the problem. The official calculation is based on “k”, a constant based on the estimated constant mass of the Sun. But the mass of the Sun ain’t constant.

As mass is lost via the solar wind and radiation (radiation energy will carry mass from the Sun due to the energy-mass relationship defined by Einstein’s E=mc2), the value of the Astronomical Unit will increase, and by its definition, the orbit of the planets should also increase. It has been calculated that Mercury will lag behind it’s current orbital position in 200 years time by 5.5 km if we continue to use today’s AU in future calculations. Although a tiny number – astrophysicists are unlikely to lose any sleep over the discrepancy – a universal constant should be just that, constant. There are now calls to correct for this gradual increase in the value of the AU by discarding it all together.

“[The current definition is] fine for first-year science courses. But for scientific and engineering usage, it is essential to get it right.” – Peter Noerdlinger, astronomer at St Mary’s University, Canada.

Correcting classical “constants” in physics is essential when high accuracy is required to calculate quantities over massive distances or long periods of time, therefore the AU (as it is currently defined) may be demoted as a general description of distance rather than a standard scientific unit.

Source: New Scientist

Posted on by Ian O'Neill

Large Hadron Collider Could Create Wormholes: a Gateway for Time Travelers?

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As we get closer to the grand opening of the Large Hadron Collider (LHC) near Geneva, Switzerland, it seems the predictions as to what we might get from the high energy particle accelerator are becoming more complex and outlandish. Not only could the LHC generate enough energy to create particles that exist in other dimensions, it may also produce “unparticles“, a possible source for dark matter. Now, the energy may be so focused that even the fabric of space-time may be pulled apart to create a wormhole, not to a different place, but a different time. Also, if there are any time travellers out there, we are most likely to see them in a few weeks…

If you could travel back in time, where would you go? Actually it’s a trick question: you couldn’t travel back in time unless there was a time “machine” already built in the past. The universe’s very first time traveller would therefore only be able to travel back to when the machine he/she was using was built. This is one restriction that puts pay to those romantic ideas that we could travel back in time to see the dinosaurs; there were no time machines back then (that we know of), so nothing to travel back to. And until we create a time machine, we won’t be seeing any travelers any time soon.

However, Prof Irina Aref’eva and Dr Igor Volovich, mathematical physicists at the Steklov Mathematical Institute in Moscow believe the energies generated by the subatomic collisions in the LHC may be powerful enough to rip space-time itself, spawning wormholes. A wormhole not only has the ability to take a shortcut between two positions in space, it can also take a shortcut between two positions in time. So, the LHC could be the first ever “time machine”, providing future time travelers with a documented time and place where a wormhole “opened up” into our time-line. This year could therefore be “Year Zero”, the base year by which time travel is limited to.

Relativity doesn’t dispute this idea, but the likelihood of a person passing through time is slim-to-impossible when the dimensions of a possible wormhole will be at the sub-atomic level at best and it would only be open for a brief moment. Testing for the presence of a man-made wormhole would be difficult even if we knew what we were looking for (perhaps a small loss in energy during collision, as energy escapes through the wormhole?).

As if that didn’t discourage you from hoping to use wormholes for time travel, Dr Brian Cox of the University of Manchester says: “The energies of billions of cosmic rays that have been hitting the Earth’s atmosphere for five billion years far exceed those we will create at the LHC, so by this logic time travellers should be here already.” As far as we know, they’re not.

Source: Telegraph.co.uk

Posted on by Ian O'Neill

Large Hadron Collider May Help Us Glimpse Into another Dimension

High energy collisions by the nearly-completed Large Hadron Collider (LHC) may be able to generate particles that are sensitive to dimensions beyond our four dimensional space-time. These exotic particles, called Kaluza-Klein gravitons, would be highly sensitive to the geometry of extra-dimensions, giving scientists an idea about what lies beyond our universe. If these particles are detected, and if their characteristics can be measured, then perhaps the extra dimensions predicted by string theory may be proven to exist…

How can you measure the size of a room without actually measuring it? Forget measuring the room, you can’t even see it! The room is invisible; it is outside your observational ability. But what if you could bounce sound off the walls? Even better, what if the walls of the invisible room were made up of resonant particles, producing their own sound? If the sound from these resonant particles could then be analyzed, the shape of the invisible room would be known.

According to string theory, there are many “invisible rooms” that we, as observers, cannot experience. We are confined to our three dimensions of space and one dimension of time (although this may not always be the case), otherwise known as four dimensional space-time. Elemental vibrating strings thread through our universe and predict that there may be six or seven extra dimensions coexisting. Although we cannot directly experience the dimensions beyond the normal four, can we measure the characteristics of string vibrations travelling from these extra dimensions into our observable universe?

In new research published by Gary Shiu, Bret Underwood, Kathryn Zurek at UW-Madison and Devin Walker at UC-Berkeley, quantum particles have been theorized to have the ability to resonate with dimensions beyond our universe; beyond the 4th dimension, considered to be time. From this resonance, signatures from extra-dimensions could pass through our four dimensional space-time to be measured. From this analysis, the “shape” of the extra dimensions may then be understood. This is not purely out of curiosity, according to string theory the shape of extra dimensions influences everything in our universe:

“The shape of the dimensions is crucial because, in string theory, the way the string vibrates determines the pattern of particle masses and the forces that we feel.” – UW-Madison physics professor, Gary Shiu.

The team predict particles carrying extra-dimensional signatures could be generated by the Large Hadron Collider at CERN (nr. Geneva, Switzerland). At very high energies, Kaluza-Klein (KK) gravitons may be created for a brief moment, carrying the signatures with them. Unfortunately KK gravitons will decay very quickly, but from this decay a shower of lower energy, detectable particles will be created. By analyzing the resulting shower, a fingerprint of the KK particle’s signature may be constructed. Any slight changes in the geometry of the detected particles may indicate a particular dimension, and many signatures may be mixed, so complex computer simulations are required to understand the results coming from the LHC.

Source: Science Daily

Posted on by Ian O'Neill

Innovative Laser Trap Captures Most Neutron-Rich Substance Made On Earth: Helium-8

Configuration of helium isotopes (credit: Physorg.com)
Configuration of helium isotopes (credit: Physorg.com)

US researchers have used a new and innovative method to create, trap and study the elusive helium-8 isotope. Helium-8, containing six neutrons and only two protons, is the most neutron rich substance we can create on Earth and until now, we have been unable to accurately characterize it. Through the use of a “laser trap”, physicists in the U.S. Department of Energy’s Argonne National Laboratory have accurately mapped the distribution of the atom and could help us understand the science behind exotic neutron stars.

So, how do you “trap” a helium-8 isotope? The answer is far from simple, but Argonne physicist Peter Mueller has found a solution. Using the GANIL cyclotron facility in northern France, helium-4, 6, and occasionally helium-8 isotopes can be generated. This is one of the only cyclotrons is the world with enough energy to generate the helium-8 isotope. It is all very well creating the particle, but to separate helium-8 from its other helium isotope siblings requires a clever and highly accurate laser “prison” for the heavier helium isotope to fall in to, whilst allowing the other, lighter, isotopes to fly straight through.

Acting as the “bars” of prison gates, six lasers are accurately aligned at such spacing that only isotopes with the dimensions of helium-8 are trapped. When aligned, helium-8 will fall between them, and should the isotope try to escape, repulsion forces keep the isotope still. Once enough time is allowed to pass (about one helium-8 atom is generated every two minutes) the team fire another two lasers into the middle at the same frequency as the resonant frequency of helium-8. Should the laser prison glow, helium-8 has been captured.

The most common, stable form of helium has two protons and two neutrons. Helium can also have two unstable isotopes, helium-6 (four neutrons) and helium-8 (six neutrons). In the unstable isotopes, the additional neutrons form a “halo” around the compact central core (pictured above). Helium-6 has a halo containing two neutrons and helium-8 has a halo of four neutrons. In the halo containing two neutrons, helium-6 has a distinctive “wobble” as the halo neutrons arrange themselves asymmetrically around the core (i.e. they bunch together). This lopsidedness moves the center of balance away from the core and more toward the halo pair of neutrons. Helium-8 on the other hand wobbles less as the four halo neutrons arrange themselves more symmetrically around the core. The laser trap is the only method known to trap a helium-8 atom, and because of this, the structure of its halo can finally be analyzed to such a high degree of accuracy.

To measure the characteristics of helium-8 is complicated by its radioactivity. Helium-8 has a half-life of only a tenth of a second, so all measurements of the atom must be taken instantly as the “prison glow” is detected. Measurements are therefore taken “on-line”, which is a difficult task in itself.

Detection of the rare helium-8 isotope is a major step to particle physicists and astrophysicists alike. It is important to understand how helium configures itself after production from a particle accelerator, but it is also of use when understanding the properties of cosmic bodies such as neutron stars. The implications of the Argonne experiment will be useful as better spectroscopic observations become available so the signature of the helium-8 structure might be detected other than on Earth.

Source: Physorg.com

Posted on by Nicholos Wethington

Paper Boomerang will be Tested on Space Station

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You know this is a burning question on the minds of eight-year olds everywhere: if you threw a boomerang in zero-gravity, would it come back to you? Japanese astronaut Takao Doi plans to test this very premise when he travels to the International Space Station in March 2008.

Doi plans to bring a paper boomerang to the ISS to test whether it will perform the trick of returning to the thrower in zero-gravity. He reportedly decided to test the boomerang at the behest of Yasuhiro Togai, a world boomerang champion from Osaka, Japan. With the announcement that a paper airplane will be launched from the ISS, space is beginning to look like an unruly high school classroom. But these experiments aren’t all fun and games, as there are underlying physical principles that can be explored by such simple tests.

A returning boomerang – when thrown properly – will travel in a circular path which brings it back around to the thrower. The two (or three) fins of a boomerang are shaped like an airplane wing, so when thrown the shape provides lift and causes the boomerang to fly.

Boomerangs fly in a circle because of the lift provided by the leading fin of the boomerang. Because it is spinning around a central axis, one fin provides lift in the direction of travel, then the other does the same. This force in the same direction makes the path of the boomerang form a circle, and as it loses energy because of the pull of gravity the boomerang comes back down to the ground.

Now, the question remains as to what will happen if the force of gravity is not present. The zero-gravity environment of the ISS is a perfect place to test this. The atmosphere of the ISS will still allow the boomerang to generate lift, but will it return to the sender, bounce off the walls, or just spin in place?

Source: Space Travel report

Posted on by Ian O'Neill

Scientists Designing “Ion Shield” To Protect Astronauts From Solar Wind

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British scientists are working to build an invisible magnetic “Ion Shield” to be used during missions in space. A minature solar wind has been created in an Oxfordshire laboratory to simulate the highly charged particles emitted from the Sun and a magnetic “bubble” is being conceived to surround future spaceships. The magnetic field should have sufficient deflecting strength to redirect cancer-causing energetic particles away from future astronauts. Useful, especially during the proposed long-haul flights to Mars should the Sun begin launching flares at the wrong time…

The protection of astronauts in space from being bathed in damaging solar radiation is paramount to mission planners. Preventing exposure to high-energy particles is essential for the short-term success of the mission, and for the long-term health of the astronaut. Generally, humans in Earth orbit are protected from the ravages of the solar wind as they are within the protective blanket surrounding our planet. The protection is supplied by Earth’s magnetosphere, a powerful magnetic shield that deflects charged particles and channels them to the north and south poles, allowing life to thrive down here on the surface. The particles injected into the poles react with our atmosphere generating light, the Aurora.

So, the UK team are looking to create a small-scale “magnetosphere” of their own. If a spaceship can generate its own magnetic field, then perhaps the majority of solar particles can be deflected, creating a protective bubble the ship can travel in during solar storms. This may sound like science fiction, but the physics is sound, magnetic fields are used every day to deflect charged particles. Why not try to build a spaceship-sized magnetic particle deflector?

“We now have actual measurements that show a ‘hole’ in the solar wind could be created in which a spacecraft could sit, affording some protection from ‘ion storms’, as they would call them on Star Trek.” – Dr Ruth Bamford, physicist at the Rutherford Appleton Laboratory (RAL) in Chilton, Oxfordshire.

Firing a jet of charged particles into a strong magnetic field was attempted in the laboratory and the results were excellent. Observing the particles “hit” the leading edge of the field, a protected volume was made within the synthetic solar wind, arcing the particles around the void.

These are very early results however, and development on any large-scale system will take some work. Lots of energy would be required to create a spaceship-sized magnetic bubble, so there will be energy optimization issues to work into the design. Whether this exciting form of protection is possible or not, the pressure will be on to build a prototype before plans for the international Global Exploration Strategy to send man back to the Moon and beyond come into action. The US is now committed to a manned mission to Mars by 2020, so it would be useful to have the solar wind, high-energy particle problem solved by then.

Source: Guardian.co.uk

Posted on by Ian O'Neill

Will Time be Replaced by Another Space Dimension?

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What if time disappeared? Yes, it sounds like a silly question – and if the cosmos sticks to the current laws of physics – it’s a question we need never ask beyond this article. Writing this article would in itself be a waste of my time if the cosmos was that simple. But I’m hedging my bets and continuing to type, as I believe we have only just scratched the surface of the universal laws of physics; the universe is anything but simple. There may in fact be something to this crazy notion that the nature of the universe could be turned on its head should the fundamental quantity of time be transformed into another dimension of space. An idea like this falls out of the domain of classical thought, and into the realms of “braneworlds”, a view that encapsulates the 4-dimensional universe we know and love with superstrings threaded straight through…

Brane theory is a strange idea. In a nutshell, a brane (short for “membrane”) can be viewed as a sheet floating in a fifth dimension. As we can only experience three dimensional space along one dimension of time (four dimensional space-time, a.k.a. a Lorentzian universe), we cannot understand what this fifth dimension looks like, but we are fortunate to have mathematics to help us out. Mathematics can be used to describe as many dimensions as we like. Useful, as branes describe the cumulative effect of “strings” threading through many dimensions and the forces interacting to create the universe we observe in boring old three dimensional space. According to the “braneworld” view, our four dimensional cosmos may actually be embedded within a multidimensional universe – our cosmic version only uses four of the many possible dimensions.

Theorists contemplating braneworlds, such as Marc Mars at the University of Salamanca in Spain, now believe they have stumbled on an implication that could, quite literally, stop cosmologists in their tracks. The time dimension could soon be disappearing to be replaced by a fourth space dimension. Our familiar Lorentzian universe could turn Euclidean (i.e. four spatial dimensions, no time) and Mars believes the evidence for the change is staring us in the face.

“One of the interesting, and intriguing, properties of these signature-changing branes is that, even though the change of signature may be conceived as a dramatical event within the brane, both the bulk and the brane can be fully smooth. In particular, observers living in the brane but assuming that their Universe is Lorentzian everywhere may be misled to interpret that a curvature singularity arises precisely at the signature change” – Marc Mars, from Is the accelerated expansion evidence of a forthcoming change of signature on the brane?.

The observed expansion of the universe (as discovered by Edwin Hubble in 1925) may in fact be a symptom of a “signature changing” brane. If our brane is mutating from time-like to space-like, observers in the Lorentzian universe should observe an expanding and accelerating universe, exactly as we are observing presently. Mars goes on to detail that this theory can explain this ever increasing expansion, whilst keeping the physical characteristics of the cosmos as we observe today, without assuming any form of dark matter or dark energy is responsible.

It is doubtful that we can ever perceive a time-less cosmos, and what would happen to the universe should time go space-like is beyond our comprehension. So, enjoy your four dimensions while they last, time could soon be running out.

Source: arXiv blog

Posted on by Ian O'Neill

Forget Black Holes, How Do You Find A Wormhole?

An artists impression of what it would look like inside a wormhole. Pretty. (credit: Space.com)

Finding a black hole is an easy task… compared with searching for a wormhole. Suspected black holes have a massive gravitational effect on planets, stars and even galaxies, generating radiation, producing jets and accretion disks. Black holes will even bend light through gravitational lensing. Now, try finding a wormhole… Any ideas? Well, a Russian researcher thinks he has found an answer, but a highly sensitive radio telescope plus a truckload of patience (I’d imagine) is needed to find a special wormhole signature…

A wormhole connecting two points within spacetime.
Wormholes are a valid consequence of Einstein’s general relativity view on the universe. A wormhole, in theory, acts as a shortcut or tunnel through space and time. There are several versions on the same theme (i.e. wormholes may link different universes; they may link the two separate locations in the same universe; they may even link black and white holes together), but the physics is similar, wormholes create a link two locations in space-time, bypassing normal three dimensional travel through space. Also, it is theorized, that matter can travel through some wormholes fuelling sci-fi stories like in the film Stargate or Star Trek: Deep Space Nine. If wormholes do exist however, it is highly unlikely that you’ll find a handy key to open the mouth of a wormhole in your back yard, they are likely to be very elusive and you’ll probably need some specialist equipment to travel through them (although this will be virtually impossible).

Alexander Shatskiy, from the Lebedev Physical Institute in Moscow, has an idea how these wormholes may be observed. For a start, they can be distinguished from black holes, as wormhole mouths do not have an event horizon. Secondly, if matter could possibly travel through wormholes, light certainly can, but the light emitted will have a characteristic angular intensity distribution. If we were viewing a wormhole’s mouth, we would be witness to a circle, resembling a bubble, with intense light radiating from the inside “rim”. Looking toward the center, we would notice the light sharply dim. At the center we would notice no light, but we would see right through the mouth of the wormhole and see stars (from our side of the universe) shining straight through.

For the possibility to observe the wormhole mouth, sufficiently advanced radio interferometers would be required to look deep into the extreme environments of galactic cores to distinguish this exotic cosmic ghost from its black hole counterpart.

However, just because wormholes are possible does not mean they do exist. They could simply be the mathematical leftovers of general relativity. And even if they do exist, they are likely to be highly unstable, so any possibility of traveling through time and space will be short lived. Besides, the radiation passing through will be extremely blueshifted, so expect to burn up very quickly. Don’t pack your bags quite yet…

Source: arXiv publication

Posted on by Ian O'Neill

A Possible Answer to Flyby Anomalies

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Artist's impression of the Galileo mission above Earth - which spent seven years (1995–2003) orbiting Jupiter. Credit: NASA

Strange things are happening to our robotic space explorers. Also known as the “Pioneer effect“ (the unexpected and sudden alterations to Pioneer 10 and Pioneer 11 trajectories measured as they continue their journey into the outer solar system), similar anomalies are being seen in flybys by modern space probes. Earth flybys by Galileo, Rosetta, NEAR and Cassini have all experienced a sudden boost in speed. After cancelling out all possible explanations, including leakage of fuel and velocity measurement error, a new study suggests the answer may lie in a bizarre characteristic of universal physics…

Planetary flybys are an essential aid to interplanetary missions to gain energy as they accelerate on their merry way to their destination. Gravity assists are accurately calculated by mission scientists so the time of arrival can be calculated down to the minute. Considering most missions take years to complete, this degree of accuracy is amazing, but essential.

So, when Galileo completed gravity assist past Earth on December 8, 1990, to speed it toward Jupiter, you can imagine NASA’s surprise to find that Galileo had accelerated suddenly, and for no apparent reason. This small boost was tiny, but through the use of the Deep Space Network, extremely accurate measurements of the speeding craft could be made. Galileo had accelerated 3.9 mm/s.

This isn’t an isolated case. During Earth flybys by the space probes NEAR, Cassini-Huygens and Rosetta, all experienced a unexplained boosts of 13 mm/s, 0.11 mm/s and 2 mm/s respectively. Once technical faults, observational errors, radiation pressure, magnetic instabilities and electrical charge build-up could be ruled out, focus is beginning to turn to more exotic explanations.

A recent study by Magic McCulloch suggests that “Unruh radiation” may be the culprit. The Unruh effect, put simply, suggests that accelerating bodies experience a type of electromagnetic radiation. At very low acceleration, the wavelength emitted will be so large that a whole wavelength will be longer than the dimensions of the Universe (otherwise known as the Hubble Distance). Low acceleration would therefore generate waves that have no effect on the body. However, should the accelerating body (i.e. Galileo getting accelerated by Earth’s gravity during the 1990 flyby) slowly exceed an acceleration threshold, the Unruh radiation will decrease in wavelength (smaller than the Hubble Distance), causing a tiny, but measurable “boost” to its increasing velocity.

Although complex, this theory is very interesting and proves that although we can calculate the arrival time of space probes down to the nearest minute, the Universe will continue to throw up some perplexing issues for a long time yet.

Sources: arXiv Blog, arXiv abstract and paper download

Posted on by Ian O'Neill

Our Virtual Reality Universe

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What if the Universe was in fact a simulation? A product of some information processor, creating space and time, energy and matter? What if the Big Bang was the whole simulation booting up, beginning billions of years of space and time calculations? Can we possibly understand our consciousness as a subroutine in an advanced number crunching machine? A new paper published by the Centre for Discrete Mathematics and Theoretical Computer Science, University of Auckland, asks us to keep an open mind and suggests if we look at the complexity of physical laws of our known universe, many paradoxes may be explained if we view our physical reality as a virtual reality.

Virtual reality is a term that has been used frequently in sci-fi novels and movies since the early 1980’s but the term artificial reality can be traced back to the 1970’s. Movies such as Tron, The Matrix and Lawnmower Man centre around the possibility of fully immersible virtual realities. It is only very recently however, with advanced interactive gaming systems and the design of complex virtual worlds online and on home computers, that we can experience worlds of sufficient detail that we can be fooled into believing what we are experiencing approximates physical reality. Additional systems have been engineered to provide the user with feedback from the virtual world they are interacting with (whether it is a rumble in the joypad or wired gloves giving the user a sense of touch), enhancing the experience beyond purely a visual one.

Taking a look at physics in our universe, many paradoxes and uncertainties exist. Quantum physics is one such field highlighted in Brian Whitworth’s research and considered to be “strange” physics, giving some justification to his theory we might actually be immersed in a virtual reality world:

“While virtual reality theory seems strange, so do other current theories of physics, e.g. the many-world view of quantum physics proposes that each quantum choice divides the universe into parallel universes. […] Even relatively main-stream physics theories are quite strange.” – The Physical World as a Virtual Reality.

Although this research pushes the envelope of the most outlandish physics theories, it is not so hard to imagine that advanced information processing may be complex enough to govern the dynamics of an entire universe (if the information processor was advanced enough). Our physical universe, after all, is approximated through physical equations and mathematical reasoning, why can’t the laws of our “physical” reality be approximated by virtual reality? If this can be done, do we actually exist in a virtual world?

Source: arXiv.org publication (abstract and full paper download)