Your Royal Highness, distinguished guests (would we have any other kind?)

I'm sure you all feel, as I do, the warmth, pleasure, and satisfaction of this moment, as the selfless work of many people culminates in the launch of the first Gemini telescope on its voyage of cosmic discovery.

Now is a good moment to

What is the purpose of an observatory?

Surely it is the increase of knowledge through discovery. It is surprising how infrequently this worthy goal is adduced as the reason for doing science. And since you are, through your own politeness and the prospect of dessert, my audience, my captive audience for a few moments-- let me say why the science of the Gemini observatory, the science of discovery, embodies an important ideal we should not be shy to articulate or embrace, or (if that is your job) to fund!

In the high councils of government, science is viewed as a rich source of technological development and economic growth. A golden goose.

Science is also seen as the key to a strong national defense. This is the replenishment of secrets faster than they leak out.

And science is strongly supported (especially by aging legislators) because of its potential to cure disease.

Who could quarrel with the prospect that science might make us rich and safe and immortal?

But I think these reasons for supporting science miss an essential idea. Science probably can help create a comfortable, secure, and healthy world, but just as importantly, science nourishes another deep human need-- our desire to learn what the world is and how it works.

Our highest aspiration is -not- perfect comfort, it is the joy of learning new things. (This is a hypothesis you could actually test here in Hawaii!) If we were rich, safe, immortal, and bored, this would -not- be a vision of paradise.

The best use of our opportunities is not a new question. Over 150 years ago, when the Englishman John Smithson left a bequest to the government of the United States, John Quincy Adams, a former U.S. President and (more importantly) an Overseer of Harvard College, authored a report to Congress on the best use of that gift. He wrote:

"The attainment of knowledge is the high and exclusive attribute of man, among the numberless myriads of animated beings, inhabitants of the terrestrial globe....To furnish the means of acquiring knowledge is therefore the greatest benefit that can be conferred upon mankind."

While a National Observatory was -not-, I am sorry to report, the immediate outcome of the Smithsonian gift, that gift did not go completely astray, as a visit to the National Mall in Washington, to Garden Street in Cambridge, or to Mauna Kea will confirm. John Quincy Adams' message was that creating the tools of discovery and using them to increase our knowledge of the Universe is something uniquely human and is the highest use of our resources.

Because telescopes are big and conspicuous expressions of our highest motives in a secular age, we are sometimes asked (most effectively, in Latin) to compare them with cathedrals-- big and conspicuous expressions of an age of faith that are found in many of the Gemini countries. (One Gemini country has an Opera House playing this role.)

They do have similarities. Neither telescopes, nor cathedrals, nor opera houses have much practical use. And these structures do have common enemies-- one steady and relentless, one erratic and variable. The dependable enemy of large structures is gravity. Daily newspapers do not need to carry gravity reports. (Down 9.8 in heavy volume.) The shifty, but more dangerous foe of these structures is wind. (I am not referring to the hot air of speakers.)

Wind is a weak force on average, but a notoriously variable and sometimes fierce force that limits durable cathedrals to the height of Strasbourg's and whose rapidly changing and unpredictable force posed -the- major challenge to keeping the Gemini mirror exactly the right shape and its structure steady for imaging the stars.

Both telescopes and cathedrals can be inspiring and beautiful places-- cathedrals for their quiet aura of contemplation and for their rich ornamentation, telescopes for the spectacular mountaintop settings (as we saw at Mauna Kea) and for their own austere lines that stem from the strictest adherence to fitness of purpose. There are no gargoyles or stained glass windows in the Gemini dome. Every detail contributes to the sharp imaging of faint light. Like the voyaging canoe Hokule'a (Arcturus to you) sailing its way to Rapa Nui (Easter Island to you), the beauty of a telescope derives from thoughtful and precise adaptation to an arduous task.

But the most important difference between a cathedral and a telescope is -not- visible in the structures-- it lies in the ideas they represent. A cathedral expresses in stone the -faith- of its builders-- their certainty about widespread but unproven beliefs. A telescope expresses the curiousity of its builders, their uncertainty and their need for evidence that makes them extend their senses.

A telescope helps serious adults answer deeper versions of the same questions groggy children ask when they wake up in the middle of a journey.

"Where are we?"
"What time is it?"
And the hardy perennial, "Are we there yet?"

The Gemini telescopes will create evidence to test our provisional, incomplete, but not completely clueless answers to these deceptively simple questions. Our place in the Universe, its age and fate sound like subjects for legend and myth. And for many centuries they have been. Here at the beginning of the 21st century, we are ready for the very first time in human history, to draw these questions squarely into the arena of measurement, so we can weigh the evidence, by using powerful tools like the Gemini telescopes.

Unlike the sleepy children who rub their eyes and have to ask the adults-- "Where are we?" -- we are now able to use telescopes, evidence from laboratories on Earth, and the accumulated imagination of generations of scientists to build for ourselves a testable picture of where we are in the Universe, to learn the age of the Universe, and to discover the surprising properties of empty space itself. These properties of the vacuum may determine the ultimate fate of the Universe. These sound like topics from mythology, but they are now thoroughly in the realm of testable ideas through 20th century physical science. We're not children anymore-- we can learn these things for ourselves.

Let me sketch our current answers and give just one example of the way Gemini will help us explore the unknown.

In the opening decades of the twentieth century we didn't know where we were. Conventional astronomical opinion held that the Milky Way Galaxy was the entire Universe. While Einstein's radical thought had produced a novel theory of gravity, General Relativity, it predicted that the Universe should either expand or contract, but not remain static.

But observers knew that the Milky Way Galaxy was not expanding or contracting, and since they thought the galaxy was the Universe, Einstein invented the Cosmological Constant-- an extra wrinkle in his equations to make the Universe have a long stationary phase.

In the 1920's, the world's greatst telescope was the 100-inch telescope at Mount Wilson, above Pasadena, California, a structure as fit for astronomical voyages as the Titanic, built in the same era with comparable technology, was fit for crossing the Atlantic. But the telescope was much luckier. Far fewer icebergs near Pasadena. Edwin Hubble used this telescope to judge the distances to galaxies, from the brightness of stars they contain. He found that the Milky Way galaxy that we live in is not the whole universe, but just one in 100 billion giant cities of stars.

This was an important step in finding out where we are. Or at least, where we are not. Not at the center of the solar system. You knew that. But the Sun is not at the center of our Galaxy either and our Galaxy is not unique, but typical.

Even more interesting, Hubble's work opened the way to finding out what time it is. He showed that galaxies are moving away from us, by measuring the stretched-out redshifted light in the light emitted by other galaxies. In a universe like that, there is a natural time-- the time since the expansion began-- and it is straightforward to calculate if the universe has been expanding at a constant rate. For modern values of distances to galaxies, that time is about 14 billion years.

But that estimate ignores gravity. Cathedral builders and Gemini telescope engineers know perfectly well that gravity is a steady opponent. Has the constant tug of gravity slowed the expansion of the universe over time?

This might seem like a topic for debate among the philosophically inclined (and it has been), but we are slowly dragging it into the arena of measurement. We can examine the light from distant supernovae, stars which exploded 7 billion years ago, to see whether the expansion has been slowing down by inferring the distance the light has travelled by measuring the supernova's brightness.

If the Universe has been slowing down, the light from an ancient explosion will reach us after a little less travel than if the universe had been coasting steadily, so the distant object will appear a little brighter than you might otherwise expect.

The actual observations have been very surprising. They do not show evidence for slowing down, but the opposite. The distant supernovae are a little dimmer than they would be in a coasting universe. This means the light has travelled a larger distance, like a snowball heaved at an accelerating schoolbus, and it suggests the universe has been speeding up.

What could do this? One strong contender is the modern version of Einstein's Cosmological Constant, now associated with the energy of the vacuum itself. This is a little like an old pair of your grandfather's spats. It is fun to try them on once in a while for a costume party, but you feel a little silly wearing them every day. But maybe that is what we will have to do.

This inference may be quite important, if true. It suggests that most of the mass-energy in the universe is of a new form, not well predicted from fundamental physics, which is making the universe expand. Telescopes can be places for learning something new about the basic make-up of the universe that we haven't learned from any experiment on the Earth.

But is it right? It is the fallible work of humans working at the edge of present understanding. And I know these people. I am one of them. "Fallible" is just the beginning of the catalog of their defects. Could it be that something less glamorous than a new form of mass-energy in the universe makes distant supernovae more dim? Something really dull-- like dust?

Perhaps. But this question will not be decided by debate or appeals to authority. We can make measurements to see what the facts are.

Gemini will help. Its excellences are sharp images and infrared sensitivity. By looking at very distant supernovae in the infrared, we will be able to tell whether it is dust or cosmology that makes those distant stars dim. We shall see. And with Gemini now coming into action, we won't have to wait long.

Where are we? In one galaxy among a hundred billion.
What time is it? 14 billion years after the beginning.
When do we get there? Well, sleepykins, I take this to mean, "When will the cosmic expansion end?" It is hard to say, but it looks like the answer is "never." An accelerating universe is one that expands without limit.

But we should remember that our present knowledge is imperfect-- it comes down from mountains on magnetic tapes, not stone tablets, and there may yet be more surprises as the first Gemini telescope finishes its shakedown cruise and voyages into the deep blue water of the unknown.

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