By Raphaella So
蘇韋霖
Dark Energy and Dark Matter
Why Do They Matter?
5%
Ordinary Matter
27%
Dark Matter 68% Dark Energy
“Seeing
is believing” is an often
heard phrase people use to justify their disbelief (or
belief) in ghosts or religion. While a good portion
of science can be proven with the tangible and
evidential, much of it also relies on theories and
models. The abstruse mysteries of the Universe,
in particular, requires an imaginative mind to
decipher, leaving many questions answered
speculatively and creating even more in the
process. Such is the case with dark energy and
dark matter.
Back in the 90s, an intriguing obser vation
puzzled physicists. We know that the universe is
made up of matter, and all matter has gravity.
For a while, there was a general consensus that
gravity would slow, or even stop the Universe from
expanding. However, all observations captured
by the Hubble Space Telescope in 1998 pointed
to a Universe that not only continued to expand,
but that expanded at an accelerated rate. The
mismatch between expectation and real it y
instigated a look into what became coined as
dark energy. The net amount of visible matter that
existed in space, on the other hand, was believed
to not possess enough gravity to hold the Universe
together. Hence, the discrepancy in matter was
coined as dark matter.
The Planck Space Mission, launched in 2009 to
create a detailed map of the Universe by scanning
for cosmic microwaves, revealed that 68% of the
Universe is made up of dark energy, while 27% is
dark matter. “Regular” matter that is observable
only occupies about 5% of the Universe, begging
the question of whether normal matter should be
referred to as “normal” in the first place.
Sci ent i s t s have yet to ag ree on how to
explain dark energy. There are several schools of
thought. The initial hypothesis was derived from
a version of Albert Einstein’s theory of relativity,
stating that what we consider as empty space
is not in fact empty, thus it would also possess
energy. This ensures that the Universe would not
be diluted as it expands, and is known as the
cosmological constant. The energy would then
cause the Universe’s expansion rate to increase,
therefore explaining the Hubble Space Telescope
observations. A second plausible hypothesis is
that there is a new type of energy that has an
opposite effect on the Universe’s expansion than
normal matter and energy. Finally, some have
offered to debunk Einstein’s theory of relativity, but
this would misplace everything we know about
the Solar System and the Universe would need
to be re-examined. All we know for relative
certainty is that dark energy is responsible for
accelerating the expansion of the Universe.
Dark matter is just as elusive. We know
what it isn’t, but have little idea of what it
is. Dark matter is anything in the Universe
that we are unable to directly observe,
unlike visible stars or planets. We can also
separate it from antimatter, which reacts
with “regular” matter to produce gamma
「
暗能量」和「暗物質」暗藏玄機？
