I am standing on the threshold about to enter a room.
It is a complicated business.
In the first place, I must shove against an atmosphere
pressing with a force of fourteen pounds
on every square inch of my body.
I must make sure of landing on a plank
travelling at twenty miles a second round the sun
- a fraction of a second too early or too late,
the plank would be miles away.
I must do this while hanging from a round planet
- head outward into space, and with a wind of aether
blowing at no one knows how many miles a second
through every interstice of my body.
The plank has no solidity of substance.
To step on it is like stepping on a swarm of flies.
Shall I not slip through?
No, if I make the venture,
one of the flies hits me and gives me a boost up again;
I fall again and am knocked upwards by another fly; and so on
I may hope that the net result will be that I remain about steady;
but if I unfortunately should slip through the floor
or be boosted too violently up to the ceiling,
the occurrence would be, not a violation
of the laws of Nature, but a rare coincidence.
These are some of the minor difficulties.
I ought really to look at the problem fourdimensionally
as concerning the intersection of my worldline with that of the plank.
Then again, it is necessary to determine
in which direction the entropy of the world is increasing
in order to make sure that my passage over the threshold
is an entrance, not an exit.
Sir Arthur Eddington
"Verily it is easier for a camel
to pass through the eye of a needle
than for a scientific man to pass through a door.
And whether the door be barn door or church door,
it might be wiser that he should consent to be an ordinary man
and walk in rather than wait till all the difficulties
involved in a really scientific ingress are resolved."
Thomas Carlyle
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