The God Particle

by Conroy

Part of the 17-mile-long LHC particle accelerator

Late last year there was breathless excitement within the physics community as several experiments conducted by CERN [1] at the Large Hadron Collider [2] under Geneva seemed to hint at the presence of a fundamental, and as yet entirely theoretical, particle: the Higgs boson. What is this particle and why did these experiments so energize physicists? The short, simple answer is that the Higgs boson is the particle associated with the Higgs field, which is hypothesized to be a ubiquitous quantum “field”. Think of it as a force or condition throughout all of space that matter interacts with. It is theorized that Higgs bosons interact with other fundamental particles (electrons, quarks, etc.) to give them mass. If detected, the Higgs boson would further validate the so called Standard Model of particle physics, one of the core theories of how the universe (the fundamental particles and forces) is structured.

The news from CERN quickly spread to the general news media and Newsweek jumped to exclaim on a cover headline that the experiments hinted at, “The Meaning of the Universe.” Other publications picked up on the Higgs boson’s nickname as “the God particle”. These headlines and reactions create the impression that this discovery, if confirmed [3], would explain many of the remaining questions in theoretical physics and provide the answers to those eternal questions that have puzzled mankind for millennia. So would it?

The Profound Questions
The Higgs boson would explain why particular particles have a specific mass. Mass is a fundamental feature of matter and explaining how mass “works” would be a tremendous breakthrough. The results would also be important in the understanding of mass-less particles like photons. But the discovery would hardly answer the even more fundamental questions about the nature of the universe, such as:

• What is the universe?
• Where did it come from?
• Why does it have the structure and forces that it does?
• Is there anything outside of the universe?
• What is the universe’s fate?

Let’s come back to these.

Everything to (Practically) Nothing

The Milky Way

There’s a terrific website – scaleofuniverse.com – that provides an interactive depiction of the size of the universe and everything in it. It’s a way to conceptualize just how inconceivably vast the totality of the universe is, and how absurdly infinitesimal are its fundamental parts. Let’s take a quick scan of this reality. Make a fist and stare at it, image it is the entire universe and you’re looking at it like God:

• Our universe is estimated to be 93 billion light years across. Light, traveling at 186,000 miles per second, would take 93 billion years to cover the current expanse of the universe.
• We can observe about 14 billion of these light years, the approximate time that light has had to travel since time began (14 billion years ago, give or take). The universe inflated faster than light a short time after the Big Bang.
• We zoom way way in to our galaxy, the Milky Way, one out of hundreds of billions, and a mere 120,000 light years across, 0.0000086 times the distance of the observable universe.
• We focus further, much further, to our solar system, which including the Oort Cloud, is 0.15 light years across, 1.5 trillion kilometers, or 0.0000013 times the distance of the whole Milky Way.
• We continue closer and see the dim Sun from Pluto, nearly six billion kilometers distant, 0.004 times the diameter of the Oort Cloud.
• We pass Jupiter, 800 million kilometers from the Sun, 0.125 times the distance from Pluto to the Sun.
• We see the Sun, shining nuclear-bomb bright, one star out of hundreds of billions in our galaxy, nearly 1.4 million kilometers across, 0.0018 the distance to Jupiter.
• We close in on the Earth, one planet of likely hundreds of billions in the Milky Way, almost 13,000 kilometers in diameter, just a spec compared to the Sun.
• We see China spread 4,000 kilometers across the Earth’s surface.
• We see Mount Everest standing nearly 9 kilometers tall.
• We see a man standing on the summit, less than 2 meters (6 feet) tall.
• He steps on a snowflake a centimeter (.01 meters) across.
• And wishes on an eyelash 0.1 millimeters (.0001 meters) thick, just about as thin as the human eye can detect.
• His heart vigorously pumps blood through his veins and he rapidly exhales moist air, red blood cells and air droplets, both about 0.00001 meters across.
• The moisture includes water molecules 0.0000000003 (3x10^-10) meters across.
• Each molecule includes two hydrogen atoms, each just 0.00000000003 (3x10^-11) meters across.
• The nucleus of those atoms is 0.00000000000001 (1x10^-14) meters across.
• The proton inside the nucleus is 0.000000000000001 (1x10^-15) meters across.
• The quarks [4] inside the proton (and the electron circling the nucleus) are 0.000000000000000001 (1x10^-18) meters across.
• Preons, the building blocks of quarks are 0.000000000000000000001 (1x10^-21) meters across.
• Neutrinos, the ghostly particles the fly virtually untouched through all of matter are smaller yet, just 0.000000000000000000000001 (1x10^-24) meters across.
• And finally to the smallest of the smallest, the theoretical strings and Plank length (the “minimum” length of anything) at 0.00000000000000000000000000000000001 (1x10^-35) meters across.

I doubt the human mind can truly conceptualize the size of anything on scales larger than the solar system or smaller than a cell (I can’t anyway). We can see the Sun and have sent space probes past Pluto. We can see the thickness of a piece of paper and understand its even smaller constituent parts. Yet the great unanswered questions lie beyond these narrow boundaries of observation and intuition.

Life on Another Planet?



by Conroy


 





Artist rendition of Gliese 581g. No one knows what it's really like.



Last week news came out about a new extrasolar or exo-planet - the sixth - orbiting the star Gliese 581. Accompanying the story of the discovery of the planet, dubbed Gliese 581g (the "a" through "f" suffixes had already been claimed by the previous five planets and the star itself), were speculations about the potential presence of life there. Based on the early calculations, Gliese 581g appears to fall within it's parent star's "habitable zone", the distance from the star where liquid water can exist on the planet's surface. It is widely believed that liquid water is the major prerequisite for life. Further, the planet's mass, diameter, density,and surface gravity all seem to be similar enough to Earth to support an atmosphere. The planet was discovered by a team led by astronomer Steven Vogt, a professor of astrophysics at UC Santa Cruz. Vogt was so confident that the planet fit the criteria for life that he said the chances of life are "almost 100 percent."

100 percent?

Not 50 percent, 90 percent, or 99 percent, but 100 percent. Now how can Mr. Vogt be so sure? The planet is far too small and dim to be observed directly. The Gliese system is over 20 light years away. In fact, Gliese is such a dim star (a red dwarf) that it cannot be observed without a telescope. By comparison, an observer on Gliese 581g - maybe there are some right now - could easily see our sun with naked eyes. Lacking direct observation, the planet was discovered using one of the only techniques available, doppler spectroscopy. This approach utilizes careful computations of the star's movement to detect the gravitation pull of revolving satellites (planets). Other complimentary techniques can be used to estimate the orbital distance and mass of the planet. Most exo-planets have been discovered using this approach. That said, "planet hunting" is a relatively new (and let's admit, pretty amazing) project in astronomy and the discovery techniques are still being refined. In fact, there have been previous claims of life-sustaining planets orbiting Gliese 581, see Gliese 581c. More detailed analysis indicated the Gliese 581c was not a good candidate for Earth-like life. Prudence demands additional observations and analysis before judgment is made about Gliese 581g's suitability for advanced life.

To that point. In order to be within Gliese 581's habitable zone, Gliese 581g has to be very close to the star (red dwarfs radiate way less energy then stars like our yellow sun), 14 million miles away or so according to preliminary calculations (the Earth is 93 million miles from the Sun). Being so close, Gliese 581g is likely tidally locked to its parent star, meaning one side always faces the star and one side always faces away (the Moon is tidally locked to Earth). As a result one side of the planet would be exposed to blazing sun and the other to deep cold. Vogt has suggested that life could proposer in the "twilight zone" along the planets perpetual sunrise/sunset horizon. Perhaps atmospheric conditions could allow adequate heat transfer from the hot sunny side to the cold dark side. Perhaps. But tidal locking seems like a bad condition for a planet that hopes to support complex life (see more below). It's equally (or more) possible that all of the water on the planet - if there is any - is frozen in ice on the dark side and not available in liquid form at all.

Speculation about life on a single planet is one thing (literally), but generalizations about the prevalence of life in the galaxy is quite another. Mr. Vogt has postulated that the potential for life within the Gliese 581 system, a star that is so close to Earth (only 116 stars are closer), and one of the first systems where planets have actually been searched for, may mean there is a hyper-abundance of Earth-like, life-sustaining planets in the Milky Way galaxy. Vogt suggested that 10 or 20 percent of stars could have Earth-like planets. Considering that there are as many as 400 billion stars in the galaxy, that could mean tens of billions of Earth-like planets in the Milky Way alone. An astounding number, and one that would suggest that life could be common in our part of the universe.

Okay, that's one position. Call me a skeptic, but I remain unconvinced. There may be a great number of Earth-like, life-filled planets out there, but I think one must consider the myriad elements that allowed life (as we understand it) to develop and flourish on Earth before we gift other planets that distinction. The Earth, our blue marble, benefits from the following amazing confluence of phenomena:

Earth. The blue marble.

1. Earth and the solar system are located in an outer band of the Milky Way galaxy away from other stars, gamma ray generators, and the galactic center where energy densities and radiation are inimical to life.
2. Earth revolves around a stable, main-sequence star that has been burning for billions of years and will continue to burn for billions more, allowing life the time to develop and evolve. Further, the Sun doesn't emit gamma rays or x-rays in bursts that could jeopardize life on orbiting planets.
3. Earth sits right in the center of the Sun's habitable zone, so liquid water can exist in the surface. The Sun's habitable zone has been extremely stable over time.
4. Earth's orbit is far enough inside the big planets, especially Jupiter and Saturn, that the planet's formation was not disrupted by their massive gravities, while at the same time these planets act as a gravitational "shield" that attract potential planetary (and life) threatening asteroids, comets, etc. from deep space.
5. Earth's orbit is far enough from the Sun to maintain planetary axial rotation (i.e. no tidal locking).
6. Earth has a small enough mass and density to be rocky, i.e. have a surface for life to grow on.
7. Earth has a large enough mass and density to (1) sustain an atmosphere and (2) maintain a geologically active metallic core, which supports plate tectonics and a planet-shielding magnetic field.
8. Earth has a nearly circular orbit, which results in relatively consistent solar radiation reaching the planet as it revolves around the sun.
9. Earth's axis is inclined just the right amount to promote seasons and overall higher temperature but avoid conditions where some of the planet is always facing the sun and some is always facing away (think of the heavily inclined axis of Uranus).
10. Earth has a relatively consistent axial tilt due to the stabilizing effects of the Moon's gravity.
11. Earth has significant tides, which may promote life through mixing of water and air, because of the proximity and size of the moon. The Moon may have formed from a freak massive collision of a small planet with the proto-Earth.
12. Earth has a high abundance of life-supporting elements (oxygen, hydrogen, carbon, and nitrogen). Earth's crust has a substantially higher proportion of oxygen than the universe in general. The oxygen may have been delivered by early random comet/asteroid impacts (or through the collision with the small planet that resulted in the Earth-Moon system).

Consider the chance and specificity of each of these elements. What are the odds that other planets will have the same congruence of elements? Maybe life-supporting planets, and by extension life is common throughout the galaxy. Or maybe Earths are very rare and special.