we often view intergalactic space as a
no-man's land of empty space time and it
mostly is about the most you'll find it
most points within it are diffuse
hydrogen atoms passing by but there are
some objects wandering will only reaches
of intergalactic space including stars
and planets and it's just possible that
there may even be somewhere in the
universe and isolated civilizations
living amongst the black expanses one
kind of object you might find wandering
in the space between the galaxies are
ejected stars often called rogue stars
these are stars that presumably formed
inside galaxies and then were ejected
out there are two mechanisms by which
this is thought to happen the first is
during the gravitational chaos that
occurs when two galaxies collide and the
second is when a multiple star system
gets too close to a black hole one
member of such a system would get sucked
into the black hole whereas the other or
others would be flung out into space
there it becomes something known as a
hypervelocity star hypervelocity stars
are just that stars moving at very fast
speed and that can be enough to escape
the gravity of their parent galaxies but
what's staggering about rogue stars is
how many of them there apparently are in
2010 and 12 an experiment called a
cosmic infrared background experiment
was launched using sounding rockets the
experiment found a strange glow coming
from intergalactic space that could not
originate from other galaxies the best
explanation was rogue stars but the
sheer amount of light that was detected
suggests that as much as half of all
stars in the universe are wandering in
intergalactic space this is interesting
because there is a mystery in particle
physics called the missing very own
problem
baryons are the particles that make up
ordinary matter a general term for
protons neutrons etc most models of the
early universe suggest that there should
be way more baryons than there appeared
to be but if half of all stars are
wandering in intergalactic space and
that could go a long way in helping to
account for the missing very ons but it
likely wouldn't only be stars wandering
in intergalactic space they might well
take their planets with them and any
life that might be living on those
planets passing so near a black hole
isn't going to be good for life but if
it arises after the ejection and perhaps
intergalactic space is teeming with life
perhaps even civilizations exist out
there completely unassociated with
galaxies there is actually one factor
that might favour such life most
galactic stars reside in high radiation
environment hostile to life such as near
a galactic core or in a star cluster the
close proximity to other stars in this
case is bad for life planets near the
galactic core would be repeatedly
sterilized by closed supernovas but the
further you get from the core out into
the spiral arms of the galaxy and beyond
the potential for life grows but there
would also likely be rogue planets
travelling without a star in
intergalactic space similar to stars
these planets would be thrown clear of
their parent galaxies through
gravitational encounters we may never
see one of these it would be incredibly
hard to spot such a thing in deep space
but they likely exist and there are even
models where these kinds of worlds can
harbor liquid water and life if the
planet has a way of keeping warm such as
nuclear decay in the core this might
create a nice shelled world similar to
europa or Enceladus or if you add a
thick hydrogen atmosphere you could have
surface liquid water intima knows what
else
one less kind of object that may lie in
between the galaxies is very different
from stars and planets it's a
hypothetical form of exotic matter that
would exhibit negative mass we're still
uncertain whether this kind of matter
exists in nature or for that matter if
we could somehow synthesizes but this
form of matter is thought to be possible
only in that it's mathematically sound
does not violate the laws of
conservation of energy or momentum but
it may violate relativity
that it could violate relativity in a
kind of loophole features prominently
when you share technological theorists
talk about creating artificial wormholes
traversing black holes and building
elsevier drives to go faster than light
most models of these potential future
technologies all require this kind of
exotic matter to exist whether we can
make this stuff is likely not going to
be cleared up anytime soon we don't have
a complete enough view of gravity all
the current theories fall short and we
really need a unified theory of
everything essentially that also happens
to be one of the greatest mysteries in
modern physics something Einstein
himself couldn't figure out but we
needed to answer the questions
surrounding negative mass but if such a
material could exist what would it be
like it would be extremely strange
indeed a normal object might weigh 5
kilograms on earth but an object with
negative mass would weigh negative 5
kilograms such an object would be
expected to be repelled by gravity in
other words it would have the property
of anti-gravity and would fall upwards
another odd expected effect of exotic
negative mass matter is that when you
push on it it would push back moving
furniture made of this material would be
beyond difficult if there was some
mechanism for this material to somehow
have been created in the Big Bang which
is a huge if it might well have been
repelled by the galaxies completely and
potentially lurks in each space at
points in between them thanks for
listening I am futurist and science
fiction author John Michael Gautier and
if you would like to help support the
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regular in depth explorations into the
interesting weird and unknown aspects of
this amazing universe in which we live
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