In 1967, a postgraduate student at Cambridge
University by the name of Jocelyn Burnell was surveying the sky with a newly constructed
radio telescope. After a few weeks she
discovered something odd. The telescope had picked up a radio signal
that seemed to be pulsating. The pulses had an interval
of exactly 1.33 seconds and were initially thought to be
nothing more than man-made interference. However, it soon became clear the signal did
in fact emanate from deep space and the unwavering precision of the pulses
was unlike anything seen before. As such, many questioned whether it was a
naturally occurring phenomenon or a transmission from another civilization. The radio source was even named LGM-1,
an acronym for little green men, and Burnell herself could not help but wonder
if she'd actually discovered the first sign of life beyond the Earth. As you might expect, it didn't take long for
natural explanations to emerge and we now know these pulsating signals
to be produced by rapidly rotating neutron stars, known as pulsars, that emit beams of radiation akin
to the beams of light emitted by a lighthouse. If nothing else, it made for a neat album
cover. Ever since, an international effort known
as the search for extraterrestrial intelligence has actively been listening for artificial
transmissions but so far we appear to be the only ones
broadcasting into the void. Humanity has been leaking radio signals into
space for the better part of a century so any eavesdropping aliens within about 100
lightyears could potentially be alerted to our presence. Beyond this invisible radio bubble, enveloping some
15,000 stars, the Earth is just another silent speck. Not only that but as technology improves,
this radio leakage is dramatically reduced. Before long, Earth may return to a state of
radio silence. If most civilizations improve and eventually
outgrow radio technology at a similar pace, the radio signature of any one civilization
may only be detectable for a very brief period of time. Furthermore, this radio leakage is extremely
faint and only grows more and more diffused as it expands into the galaxy. Some of the most powerful signals to leak
into space are military radar emissions and stand a much better chance of detection
across interstellar distances than the average television broadcast. The Square Kilometer Array, a vast interferometer
to be constructed in South Africa and Australia, could be sensitive enough to detect the faint
radio signature of an earthlike civilization out to a distance of several hundred lightyears. To detect more distant signals would require
more deliberate attempts at communication. For instance, advanced civilizations
may construct powerful beacons specifically to increase their radio luminosity. These beacons would be rather expensive to maintain
as they would consume vasts amounts of energy for extended periods of time. A less expensive alternative
would be a focused beam of radiation as opposed to an
omnidirectional broadcast. In 1974, the Arecibo Observatory in Puerto Rico
famously beamed an interstellar message towards a globular cluster some
25,000 lightyears distant. The message took less than 3 minutes to transmit
so any prospecting aliens in the path of that signal would have less than 3 minutes to detect it,
and they will never get a second chance. We may have been on the receiving end of such
an interstellar message when, in 1977, a momentary burst of energy
swept across the planet. Repeated attempts at redetection notwithstanding,
the famous Wow! Signal was never detected again and its origin
has never been conclusively ascertained. On the slim chance
that it was of artificial origin a reply was beamed in the
general direction whence it came in 2012. In a galaxy as old and vast as the Milky Way,
the probability of two civilizations stumbling upon one another by briefly screaming
in random directions is not great. To increase our chances, we need to limit
our selection of targets by searching for other technological and biological signatures. In 1995, the first extrasolar planet orbiting
a sunlike star was discovered. We now know the vast majority of the hundreds
of billions of stars in the Milky Way galaxy are home to at least one planet. We also know that billions of those planets
are of similar size to the Earth and orbit within the habitable zone
of a star similar to the Sun. This means that liquid water could exist on
the surface which is an essential ingredient for life as we know it. Furthermore, billions of extrasolar moons
may also be capable of supporting life. With this knowledge in mind, in 2017, a message
was beamed towards one of the least distant and most earthlike exoplanets
discovered to date. The message comprised a number of musical
compositions and basic information about humankind and should the planet be inhabited we could
expect a reply as early as 2044. Here's a quick preview of that future. However, habitability is no guarantee of habitation. To determine whether a potentially life-supporting
planet is currently supporting life would require a more careful examination. For instance, by analyzing the starlight passing
though the atmosphere of an exoplanet, it is possible to deduce its chemical composition. The spectrum of an oxygen-rich atmosphere will
differ from that of, say, a hydrogen-rich atmosphere. Given that photosynthetic plants and organisms are
responsible for the large quantities of oxygen on Earth, an exoplanetary atmosphere with a similar
concentration of oxygen could be taken as a sign of life. This is known as a biosignature. But it's far from definitive as oxygen could also
be the result of various abiogenic processes. As such, astrobiologists are more interested
in certain chemical combinations as it would be far less likely for, say, methane and
carbon dioxide, to coexist in the absence of life. Speaking of carbon dioxide, some chemicals
could be indicative of industrial pollution and thus artificially induced climate change
could serve as the universal sign of unintelligent life. In addition to biosignatures, we may be able
to detect signs of technology. For instance, an exoplanet surrounded by a dense
orbital belt of artificial satellites or space debris could be detected during transit
of its parent star. This would be an example of a technosignature. A more extreme example
would be a megastructure. The initial speculation surrounding the discovery
of pulsars has become somewhat of a recurring theme. Whenever an astronomical discovery
initially defies explanation, vigorous speculation about aliens
take center stage. In more recent years, this discussion has been dominated by a peculiar star some 1,500 lightyears distant. The star exhibit erratic light fluctuations
and occasionally dim by as much as 22% and so one hypothesis is that an alien megastructure
is blocking the light from the star. While evidence of astroengineering is still
within the realm of possibility, the dimming is now thought to be caused
by nothing more than dust. The existence of circumstellar megastructures
was popularized by theoretical physicist Freeman Dyson back in 1960
as a potential means for advanced civilizations to harness the energy of their parent star. Commonly known as a
Dyson sphere or Dyson swarm. According to the Kardashev scale, a method
of measuring a civilization's energy consumption proposed by astrophysicist
Nikolai Kardashev in 1964, a Dyson sphere would be indicative
of a Type II civilization. A Type I civilization could harness the energy
of its home planet. A Type II civilization could harness the energy
of its parent star. A Type III civilization could harness the
total energy output of an entire galaxy. Extensive surveys of billions of stars notwithstanding,
there is no reliable evidence of a Type II nor Type III civilization
in the Milky Way galaxy... ...so far. What about extragalactic life? After surveying 100,000 nearby galaxies for
signs of a Type III supercivilization, astronomers found no signs
of a galactic empire. The great silence of the universe can be a
bit unnerving. Humanity is now on the verge of detecting
biosignatures on extrasolar planets but Earth has been radiating
detectable biosignatures for billions of years, yet, as far as we can tell, it's failed to attract
the attention of any alien astronomers. The apparent contradiction between the expectation
and lack of evidence for extraterrestrial life is known as the Fermi Paradox. Given the sheer size and age of the universe,
why does it appear to be so lifeless? It is possible to concoct
a myriad of hypothetical solutions. Perhaps life is common while intelligent life
is exceedingly rare. After all, it took some 4 billion years of
evolution and a number of mass extinctions before humans emerged on Earth. Proponents of the rare Earth hypothesis suggest
that complex life on Earth is the result of an improbable chain of events
unlikely to occur more than once. Perhaps there exists a barrier, either improbable
or impossible for life to overcome. If the barrier is behind us, we may be among
the fortunate few to have crossed it. Potential candidates include the emergence
of multicellular organisms and the invention of nuclear weapons. If the barrier is still to come, we may soon join
the cosmological graveyard of fallen civilizations. Potential candidates include
unsustainable climate change and the invention of nuclear weapons. Perhaps we severely underestimate how truly
alien aliens can be. All life on Earth is carbon-based and rely
on water but life could hypothetically be silicon-based and thrive in
oceans of liquid ammonia. Just as we search for life as we know it,
aliens may be doing the same. Perhaps an advanced civilization did in fact
pay us a visit in the distant past. Unless some sort of evidence of that visitation
survived for millions or billions of years, we'd never know. Even a visitation in the recent past could have been
misconstrued as gods descending from the heavens. Well, I mean, that would have been a fairly
accurate interpretation. Perhaps all civilizations inevitably develop
technology that transcend physical reality. For instance, reality could be rendered obsolete
by hyperrealistic simulations. By transferring ones consciousness into these virtual
wonderlands, one could achieve digital immortality. The happenstance offerings of nature would
struggle to compete with the promise of utopia. Throughout the galaxy, pockets of advanced civilizations
may occupy no more than a few star systems as they explore inner space
in place of outer space. In his transcension hypothesis, futurist John Smart
takes it a step further and suppose this introverted evolution will progressively miniaturize
computers until they are so intensely compressed that they generate an environment
analogous to black holes. These postbiological civilizations would thus
transcend the spacetime continuum and vanish from the visible universe. Hypothetically speaking. Apart from artificial transmissions and distant
signs of astroengineering, there's also a far less remote
form of technosignature. The Voyager spacecraft was launched in 1977
and, as of the making of this video, it is the only probe to have
reached interstellar space. It famously carries a golden record
with information about mankind but it will take another 40,000 years
before the probe encounters another star. In an effort to more expeditiously explore
the galaxy, an advanced civilization may launch sophisticated interstellar probes capable
of self-replication. These probes would be intelligent enough to
mine the available resources in any given planetary system
to create copies of themselves. These copies would then travel to neighboring
systems and create additional copies. If these probes could travel at just
10% of the speed of light, a speed attainable by modern methods of propulsion, every corner of the galaxy could be
exhaustively explored in just a few million years. A relatively short amount of time
on cosmological timescales. Mankind is now fast approaching the technological
sophistication to launch such a probe. This begs the question... Why is the Solar System so probeless? If human progress is any indication, the galaxy
should be completely overrun by self-replicating automata,
yet we see no evidence of that. An ongoing hunt for alien artifacts has yet to locate
any covert probes lurking in the Solar System but space is vast. An object of extrasolar origin could easily
be zipping around our cosmic backyard without our knowledge. In fact, that is exactly
what happened in 2017. An extrasolar object, named 'Oumuamua, passed
through the inner Solar System and went completely unnoticed until it was
moving away from the Sun. Even then, its discovery was pure luck and
thousands of extrasolar visitors could go undetected each year. The size and shape of 'Oumuamua can only be
inferred by the amount of light it reflects but it appears to be highly elongated
or extremely flat. Initially, it was thought to be a comet but
the absence of a cometary coma, a trailing cloud of dust and gas
typically formed when comets approach the Sun, lent credence to it being an asteroid. But then the object began to accelerate. This acceleration would be consistent with
the outgassing of a comet but, as mentioned, 'Oumuamua does display the expected characteristics
of a comet. One possibility is that this outgassing is simply too faint
for us to detect but there is that remote possibility of it being an interstellar probe. More specifically, a probe using a light sail
as a means of propulsion. On the other hand, 'Oumuamua is perfectly
radio silent. Perhaps it's a defunct probe, destined to
aimlessly roam the galaxy, much like Voyager. It's important to remember that
with a sample-size of one, that being Earth, we cannot possibly know how
common or rare life truly is. There could be hundreds of planets or millions
of galaxies between us and them. If life was discovered elsewhere in the Solar System,
perhaps beneath the frozen mantle of Europa, we'd be able to compare and contrast
two distinct sources of life and gain crucial insight
into its commonality or rarity. Many reject the anthropocentric view of Earth
as a cosmological oddity due to the sheer number of earthlike planets
coupled with the resilience of life on Earth but the truth is, we don't know. We don't know if billions of planets is sufficient
for intelligence to arise more than once. We don't know the prerequisites for abiogenesis,
the transition from non-life to life. We don't know the probability of cosmic solitude. But to conclude that we are alone in the face
of all this ignorance is more than a bit presumptions. The extent of our search for extraterrestrial
intelligence has been compared to searching a glass of water for evidence of fish in all
of Earth's oceans. Space is unimaginably vast and we have barely
begun to scratch the surface. There are so many untapped avenues for detecting
signs of life that if we just turned that telescope a bit to the left, made it a bit larger, and listened
to a slightly different range of frequencies perhaps the universe wouldn't be so silent.
The next video must be a Top 10 Facts - 2018, So that's 5 videos this year (not including the top 10 facts 2017)
last year he uploaded 10 videos before the annual Top 10 Facts - 201x
in 2016 = 13 videos
2015 = 32 videos
LETS GO BOYS HES ALIVE
The title is the period of time that takes him to make this awesome videos.
Alternate title: the time between LEMINO videos. Keep up the great work man!
I am a simple man. I see a Lemmino video, I click a Lemmino video.
almost failed in my last hours of no nut november after seeing that upload notification
I think this may be the best editing yet. The way the story begins and ends on the LGM noise is as poetic and lonely as the subject of the video itself.
"Some chemicals could be indicative of industrial pollution and thus artificially induced climate change serve as the universal sign of UNTELLIGENT life"
haha
Holy crap both Lemino and ERB uploaded for the first time in months within minutes of each other