Watch out for and report aggressive geese

A female Canada goose protects her nest.

It's mating season, the time of year when Canada geese aggressively defend their nests and goslings. This instinctual behavior is understandable in the wild, but problems arise when the nests are in human high-traffic areas, such as near building entrances. Geese view people who need to enter those buildings as intruders.

Employees and visitors have encountered geese that have threatened and chased them, and a small few have been struck or hurt by the birds. When injuries occur, they are usually minor and due to a fall from trying to elude the goose. However, one employee this year was injured by a goose that flew onto the employee's shoulder and attacked. The employee suffered a scratched shoulder and a bruise on the head. The incident required first aid and time off work.

If you get near a nest or gosling, you may hear a goose's defensive hiss. This is typically a first warning. If you are near their young, the birds may charge or fly at you. The aggressive behavior usually lasts from the time eggs are laid until the offspring take on adult coloring in May.

Here are some tips for dealing with aggressive Canada geese.

• Know where geese are likely to be in your area. Watch for geese and avoid nesting areas and goslings.
• Show them who is boss: When challenged by a goose, Fermilab's Roads and Grounds Department workers recommend making yourself look larger and more threatening by yelling and flapping your arms. Maybe it doesn't look especially cool, but this technique has been highly effective in getting geese to back down.
• Protect yourself. If a goose attacks, or threatens to attack, put whatever items are available to you, such as a briefcase, purse or umbrella, between you and the goose.
• Most importantly: Please report problem geese and their locations as soon as possible to Roads and Grounds at x3303. This can help to prevent others from being harassed or attacked by the same goose. Roads and Grounds staff can place temporary fences between nests and walkways or apply deterrent chemicals to grassy areas where geese forage.

Fermilab has also contracted with the Geese Police, a goose-control company from Naperville, that employs specially-trained border collies to chase geese away from building entrances and lawns. This technique may take a few days to work, but is highly effective.

Is dark energy getting weaker?

From New Scientist, April 10, 2009

After billions of years of runaway expansion, is the universe starting to slow down? A new analysis of nearby supernovae suggests space might not be expanding as quickly as it once was, a tantalising hint that the source of dark energy may be more exotic than we thought.

For more than a decade, astrophysicists have grappled with evidence of a baffling force that seems to be pushing the universe apart at an ever-increasing rate. Exactly what constitutes the dark energy responsible for this cosmic speed-up is unknown, says Michael Turner at the University of Chicago. "The simplest question we can ask is 'does the dark energy change with time?'"

So far, the evidence has suggested that dark energy is constant, though its effect on the universe has become stronger as the universe has expanded and the gravitational force between objects weakens with distance.

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What happens at absolute zero?

From Globe and Mail, April 10, 2009

When something is cooled to absolute zero (Kelvin), do the electrons and other sub-atomic particles stop moving? Or does "absolute zero" only mean that movement stops at the molecular level (as opposed to the sub-atomic level)? Peter, Someplace, World

I've heard that at absolute zero molecular motion stops. But what happens to electrons, do they also stop? If they do, what prevents them from falling into the nucleus? William, Austin, Texas, USA

Absolute zero is zero degrees on the Kelvin thermometer scale; it corresponds to about -460 degrees Fahrenheit and -273 degrees Celsius.

Even space isn't that cold. The lingering afterglow of the big bang heats space to 3 degrees Kelvin, on average - some colder pockets exist. The Boomerang Nebula (at 1 degree K, 5000 light years away) is the coldest known natural spot in the universe.

We have artificially lowered the temperature of atoms on Earth to almost absolute zero. Atoms near absolute zero slow by orders of magnitude from their normal room-temperature speed. At room temperature, air molecules zip around at about 1800 kilometres an hour. At about 10 micro degrees Kelvin, Rubidium atoms move at only about 0.18 kilometres an hour - slower than a three-toed sloth, says physicist Luis Orozco of the University of Maryland.

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