parameters18

Alpha Centauri A, B and C. You can get to Alpha
Centauri from here by looking through a telescope,
like Hubble. Or you can imagine yourself getting there
by sending, as Sagan and Drake have, electromagnetic
signals. Or you can even imagine yourself having been
there ("we have visited all the planets except Pluto" is
a common phrase nowadays) by sending robots. This
is close to standing on the reddish planet, but the
parameters of galactic distances take over when you
think of travel even this materially: The fastest
explorer robots ever launched, Pioneers 10 and 11,
and Voyagers 1 and 2, will take tens of thousands of
years to cover about 4.3 light-years.
The solution to traveling between stars and galaxies
might have to do not only with where exactly we want
to go, but also with what we mean by being there.
Our sense of "being there" is bound up tightly with
the methods, attitudes and ideas of science and
technology. I'm saying we can't "be there," for
example, because we do not have the technology to
move physical objects across light-years of space
within a human lifetime, or anything even remotely
approaching the confines of a human lifetime.
Furthermore, no one really expects scientific methods
to develop workable possibilities for transcending the
parameters of light. Not anytime soon, at least. For
these reasons, "being there" cannot mean standing on
the rock-red living surface of a planet outside our own
solar system.
Distances even inside the galaxy restrict us from
visiting worlds that far away. Our problem, if we want
to travel to Planet Alpha Centauri, is to overcome the
physical prohibition of traveling 4.3 light-years
through an uninhabitable vacuum. A parameter of the
universe is that human beings cannot physically travel
from Earth to other stars.
As Drake, Sagan and Hubble have all understood,
however, human beings can travel these interstellar -
and intergalactic - distances in principle. Or, to put it
another way, we can imagine ourselves sending
representatives to and collecting representatives from
these other places. We send and collect, for example,
beams of electromagnetic radiation, hoping to put
ourselves there, in a sense. Closer by, we send robot
spacecraft to land on Mars and Venus and to fly by
moons and planets, putting ourselves there.

To be there, in one sense, is to have some knowledge
of there. For the scientific imagination, "knowledge"
means a body of physical data, together with logical
inferences about the data. Physical data are obtained
from, roughly speaking, any stably, constantly
occurring or recurring objects or events in the
universe. Anything that can be duplicated in the
laboratory, or consistently observed from one time to
another, constitutes the data of science. Trees are
constantly there, and as such provide scientific data.
Biological systems are constantly there. The objects
and events of outer space are constantly there, and can
consistently be observed from one time to another. As
scientific instruments become more refined and
precise, the data - the numbers and the logical
inferences - can change. But the objects and events
remain. They are all there.
Some objects and events that are clearly there pose
special problems for science. The difference, for
example, between living and nonliving things is a
major problem for science. It is not clear what
distinguishes living cells from a group of nonliving
amino acids. Human consciousness, for another
example, is also a problem. It is clearly there, and yet it
cannot be strictly quantified or empirically explained.
The idea that the brain is composed of complex
chemical and electrical interactions goes a long way
toward explaining conscious activity in scientific
terms, but it still does not account for consciousness
itself.
Another event that poses major problems for science
is a dream. Dreams clearly exist, they are clearly there.
But their functions and indeed the parameters of their
existence are merely topics for speculation. All
scientists really "know" about dreams is that they
exist, that they seem to occur at particular times, and
that some few chemical interactions take place in the
body during dreaming. Dreams are apparently a
function of consciousness.
All this is to say that scientists, despite over four
hundred years of methodical data-gathering and
inference, really have no scientific explanation for the
there of human consciousness.
We do know, however, that we can consciously
imagine ourselves to have been in deep space, not only
through fantasy Captain Kirk and the Starship
Enterprise - but through imagination: Hubble
penetrating the realm of the nebulae, planetary