As
I have already said in this
post and on Twitter
(@scienceontoast), my recent adventures in the world of online science communication
have rekindled a childlike enthusiasm for cool science that I have not felt for
many years.
The
unimaginably vast and mysterious universe is at our fingertips like never
before thanks to fast internet, clever web content, and the power of social
media and collaborative projects such as Wikipedia.
I've
heard it said that the human mind simply cannot comprehend nor
imagine the sheer size and scale of our universe. This may be true, but a
clever web app by Cary Huang helps us get a little bit closer. (Thanks to
Ashley Youett who originally sent me the link. It's been popular since on
Twitter).
The Scale of the Universe 2 is a
window with a sliding scale bar which the user controls to zoom through
the length scales of the universe, starting out on our human scale and then
delving down through the realm of the ant, the human ovum, bacteria and
viruses, through our own DNA, atoms and molecules and right down to the
nucleons, quarks and finally the Planck length, the fundamental quantum unit of
length. Each object has a picture showing its relative size
and potted info on each item is available with a click. I
counted 12 empty orders of magnitude (a factor of
1000000000000) between the smallest elementary particle and the Planck
length. To very tenuously paraphrase the great Richard Feynman, "there's
plenty of room at the bottom". The universe really is an incredibly empty
place.
Zooming
back out quickly to the human scale again, we then start pulling back the
camera to explore larger and larger objects. We learn that a marathon runner
would have a good chance of running from pole to pole on a neutron star without
stopping for lunch (but would succumb to some heinous gravity) and that the
projected size of the moon is about the same as that of the continental USA (or
Australia!).
The
most fascinating part for me, though, is the stars. The stars cover sizes only
a bit bigger than the Earth (the example is the white dwarf Sirius B), and in
relative star sizes, the Sun is not really much bigger. Stars can really be
stupendously large, with the largest red giants on the scale 10000 times bigger
than the Sun!
We
draw back further and swim through planetary nebulae, star clusters and
galaxies. It astonishes me to think that in every single galaxy out there in
the universe there are hundreds of billions of stars and I feel convinced that
our there somewhere, perhaps even in our big sister Andromeda, there is
intelligent life gazing out into space with the same sense of unfathomable scale
and longing.
As
we survey the galactic clusters that make up the larger superclusters and the
filamentous structures that are formed by the distribution of matter in our
universe, we eventually reach a limit: since light takes time to reach us, each
distance further we can see takes us further back in time. We can see so far
back in time, in fact, that distant universes are mere embryos, relics from
much earlier in the history of the universe than we are in the present day. We
can see so far back that we can see the very point at which the opaque soup of
the universe first became transparent. Beyond this, we can see no more!! This
is the limit of the observable universe, the curtain beyond which we can no
longer reach the enquiring power of our telescopes. The nebulous grey
beyond this in The Scale of the Universe 2 represents
our uncertainty about exactly what comes before (although we have a pretty good
idea right up to very, very early times in the formation of the universe, but
for that we will have to talk about the Large Hadron Collider).
The Scale of the Universe 2 is by no
means the first of its kind I’ve seen (and I assume there was a Scale of
the Universe 1) but it is a fascinating tool to help us understand, in some
small way, the true scale of the universe. It is also useful for one of my
favourite pastimes... making my mind boggle, on purpose!
