So we all know that our universe is made of atoms and
thus made of matter, but the most surprising thing that we have discovered
about the universe is that we don't know what it is made of... Of course its
made of matter, but it only is a small percentage of matter...The rest dark
matter and dark energy........
Astronomers know it exists because something
in the universe is exerting significant gravitational forces on things we can
see. When they measure the effects of this gravity, scientists estimate that
dark matter adds up to 23 percent of the universe. Normal matter accounts for
just 4.6 percent. And another cosmic mystery known as dark energy makes up the
rest – a whopping 72 percent .
So the big question is : How do
scientists study the stuff when they can't see it?
But lets get down to
basics.....How do we even know that dark matter exists? Could it be that the
whole scientific community wanted to play a prank on us and came with
the word "Dark matter" to make us feel......excited? Nope, Dark
matter is real 100% no joke.....
How do we even know that dark matter
exists?
Easy get a weighing scale and measure the
weights of galaxies...
Yeah no, you can't do that... but that is the way
scientist found out about Dark matter. By weighing
galaxies.... astronomers hoped to measure was the mass of a galaxy.
But you can't just weigh something the size of a
galaxy – you have to find its mass by other methods.
One method is to measure the light intensity, or
luminosity. The more luminous a galaxy, the more mass it possesses. Another
approach is to calculate the rotation of a galaxy's body, or disk, by tracking
how quickly stars within the galaxy move around its centre.
Variations in rotational velocity should
indicate regions of varying gravity and therefore mass, but here
where the problem came up.
When astronomers began measuring the rotations of
spiral galaxies in the 1950s and '60s, they made a puzzling discovery.
They expected to see stars near a galaxy's center,
where the visible matter is more concentrated, move faster than stars at the
edge. What they saw instead was that stars at the edge of a galaxy had the same
rotational velocity as stars near the centre.
Astronomers observed this first with the Milky Way,
and then, in the 1970s, Vera Rubin confirmed the phenomenon when she made
detailed quantitative measurements of stars in several other galaxies,
including Andromeda
The implication of all of these results pointed to two
possibilities: Something was fundamentally wrong with our understanding of
gravity and rotation, which seemed unlikely given that Newton's laws had
withstood many tests for centuries. Or, more likely, galaxies and galactic clusters
must contain an invisible form of matter – hello, dark matter –
responsible for the observed gravitational effects. As astronomers focused
their attention on dark matter, they began to collect additional evidence of
its existence.
So now what's up with Dark matter and cancer?
Dark matter is made of WIMP's. I mean
obviously Weakly interacting Massive Particle. So that means that
Although dark matter make 26% of our universe
it doesn't necessarily interact with normal matter which we can
interact with on a daily basis .If the dark matter within our galaxy is made up
of Weakly Interacting Massive Particles (WIMPs), then millions,
possibly billions, of WIMPs must pass through every square centimeter of the
Earth each second.
Our solar system goes around the center of the Milky
Way in an orbit that takes some 220 million years to complete. We therefore
move into the dark matter which ought to move around the galaxy in a
non-rotating fashion, and hence dark matter particles pass (rapidly) through
the Earth all the time. The probability that a dark matter particle interacts
with the matter that we are made of is small, but every once in a while it
ought to happen.
There are now many experiments under way looking for
these rare interactions between dark and visible matter. The experiments
consist of large tanks that contain certain atoms with desirable properties.
Different experiments use different atoms, but they all search for the tiny
recoil that an atomic nucleus would get from a dark matter particle. The
detectors then either measure the heat created by this interaction, or the
light that some atoms emit following the interaction, called “scintillation.”
So let's take our body for a while now and count how
many atoms are in it? A healthy 70 kg adult would have around 7*10^27 atoms in
the body give or take a few. And considering that occasionally dark
matter may interact with the earth which has a whopping 10*50 atoms we can
calculate he fact that the probability of Dark matter just interacting
with you would be...
10^27*7/10^50 which gives you 7e-23=
0.0000000000000000000000.1.
So yeah basically none. Also
we haven't considered the fact that your Cells should go out of
control and start a Cancer. So despite that being cool that you could get
cancer from dark matter its pretty impossible!!!!!!
DNA for building Dark matter detectors....
But there is neat way to track the direction of
incoming dark matter particles which was proposed by Drukier et al. in a 2012 paper.
Their idea is to use the breaking of straight (not curled up), closely spaced,
DNA strands to reconstruct the recoil of an atom hit by dark matter.
Their experiment works as follows: wait until a dark
matter particle interacts with a thin layer of gold, and kicks out one of the
atoms. The gold atom carries on much of the momentum of the dark matter
particle, so it will continue into about the same direction. Below the gold
layer there are the DNA strands hanging, and whenever the gold atom hits one,
the DNA is likely to break. From the dark matter particle, the gold atoms get
about enough energy to break a few hundred of the strands.
Now if one knows the sequence of the DNA strands being
used, they constitute basically a coordinate system. What one has to do then is
sweep up the broken off DNA ends, find out where they were broken, and
reconstruct the path of the gold atom, thereby revealing the direction from
which the dark matter particle came.
But what really intrigues me is why only DNA? We
could use any Nano Polymer to do so. According to the paper which the
idea was published it does seem pretty good. Who knows if the undetectable
could be detected by something that every living thing on the planet
has......Deoxyribo Nucleic Acid.
, DNA
