We know that “invisible” energy, such as radiation,
certainly can lead to big problems. We know that space certainly is dangerous,
and that as soon as you leave Earth’s atmosphere you’re at the mercy of so many other threats. But
should we also be more wary of even the most fundamental conditions of reality, as well?
This is Unveiled, and today we’re answering the extraordinary question;
could an explosive gravity wave ever wipe out life?
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Thankfully, in modern times, we’ve gotten gradually better at handling many natural
disasters on Earth. They still have the potential to wreak immense havoc and cause catastrophe… but,
statistically, their impacts are less than they’ve ever been before. That
same level of optimism, though, doesn’t extend out into space.
The worrying truth is that we’re almost completely unprepared for most cosmic disasters. Overall, we
rely on just sheer chance that an asteroid doesn’t crash into us… or that a solar flare is never
powerful enough to totally fry our world. Even an asteroid impact is small, however, compared
to the immense destructive potential some of the other objects and forces in space could have.
When a star explodes and goes supernova, for instance, it can produce more energy in just a
few weeks, days, or even hours than our sun will in its entire lifespan. Currently, we would have
literally no chance if we ever got in the way of one that was nearby. Black hole eruptions are also
among the most violent events in the universe, and another that we’d be powerless against. A
supermassive black hole in the Camelopardalis constellation, for example, has staged regular
“eruptions” over millions of years... and has so far yielded more energy from them than 60 billion
supernovas combined. But still, beyond even that, the two most powerful events in the known universe
are gamma ray bursts and supermassive black hole collisions. Gamma ray bursts are essentially
high energy jets of gamma-level light that zap through space…. which scientists still don’t
properly understand. Meanwhile, supermassive black hole collisions are so powerful that
they create invisible ripples in actual spacetime… and it’s these that we call gravitational waves.
Gravitational waves weren’t always recognized as a real phenomenon. Albert Einstein and Max
Abraham are credited as being among the first to predict their occurrence, and despite this,
Einstein regularly second guessed himself. It’s said that Abraham, in particular,
had been led to the conclusion of gravity waves via one relatively simple question;
if electricity produces electromagnetic fields as radiation, then does mass similarly cause
gravitational radiation? In Einstein’s case, he first predicted gravitational waves as an answer,
then doubted them… and then changed his mind again before doubting them again
decades later. Clearly, he was never sure, and they weren’t ever proven
in his lifetime. The first confirmation of gravitational waves didn’t come until 2015.
In the broadest sense, these waves are radiated whenever massively energetic or destructive events
take place, they warp spacetime for lightyears around, and they manifest as powerful ripples that
propagate through space like tidal waves. There is a lot of power behind them, though, so are we also
in danger thanks to them? This was a question that many physicists had on their minds when gravity
waves were initially accepted; could these epic cosmic structures transfer their energy to matter
and cause damage? Could they hurt or even kill any life (including us) that gets in their way?
To understand this, it’s key to know how gravitational waves
actually interact with matter. When they hit something in space - such as a planet,
like Earth - they actually pass right through seemingly with no major consequences. Although,
this is certainly up to interpretation. The physicist Richard Feynman showed the complexities
at play here with a thought experiment he created in 1957, at a conference for general relativity.
He named it the Sticky Bead Argument and it was designed to show how gravitational waves (then
theoretical) perhaps could transfer energy to matter. In the experiment there are two beads
positioned around a rod. When gravitational waves pass through this setup, they release
energy in a perpendicular direction. When this release causes the beads to hit the rod head-on,
the rod itself remains unaffected… but when the beads strike from the side, there’s energy
through friction created with the rod. The gravitational wave has had a physical impact.
Imagine Feynman’s Sticky Bead Argument on a much larger scale,
and the same thing happens when the same waves pass through planets - again,
including Earth. Under the right conditions, it’s thought that the energy released could even cause
a planet to noticeably expand and contract. This squeezing would affect the entire world,
were it to happen… but how severely depends on the energy the waves have at the time when they
hit. The first gravitational waves that scientists were able to measure (in 2015) originated from a
huge supermassive black hole collision, but one that had happened almost 1.3 billion lightyears
away…. so we only received a very small portion of their overall power. In this case, then,
while the waves did have an effect, it was found that they only shifted our planet by a
distance of about twelve protons - a microscopic nudge that wasn’t threatening in the slightest.
Nevertheless, the energy that these gravitational waves held was still
immense. They may have moved our world by “only” a few protons, but they were created
by the colossal meeting of two supermassive black holes; one with 29 solar masses and
the other with 36. What’s really interesting (and perhaps concerning) for today’s question,
though, is that upon colliding and fusing into an even larger black hole, the new
combined entity’s mass was found to be just 62 solar masses. Meaning, with some quick math,
we can say that three entire suns’ worth of energy had been transformed during the meeting
into radiation via gravitational waves. Clearly, then, these things are not to be taken lightly.
Fortunately for us, however, gravitational waves also don’t interact with matter in
quite the same way as light radiation does. As we currently understand them,
only a fraction of a gravitational wave can ever directly affect or influence us. But still, it’s
clear that if the right scenario were to unfold, then that could certainly be enough to cause some
big problems. If, say, those waves had formed much closer to us - just one astronomical unit away,
for example - then they would have stretched and compressed Earth by about three feet. A much more
dramatic result. But, still, that in itself isn’t necessarily a problem. Earth already goes through
something similar, with the effects of the moon pulling and pushing our world on a regular basis.
But, what matters (with gravitational waves) is how quickly it would happen. The energy transfer
would all occur at once - not gradually, as with the moon - and could therefore have the effect
of heating up our planet to an immense degree, and even shattering some of its core. Move the
wave-causing event even closer to us than the sun is, and the effects would be greater still.
Under such potentially incredible strain, the ground would shake and various natural
disasters could unfold all over the world map at essentially the same time. With a strong enough
gravitational wave formed close enough to us, the push and pull perhaps could trigger earthquakes,
tsunamis, and volcanic eruptions, all at once. Those in turn could breed more disasters; fires,
floods, landslides, and storms. Ash plumes choking the skies before blanketing the ground,
contaminating water and plants, and potentially melting infrastructure.
In the very worst case scenario, it could rock civilization and incapacitate most of humanity.
However, what’s key is that for a strong enough wave to even potentially achieve all of that,
it would have to be carrying an immense amount of energy - even by gravitational
wave standards. It would likely have to have formed via either an unprecedented cosmic event,
or due to a still-massive black hole collision of some kind that’s also on our doorstep in
space terms. Today, there’s zero suggestion that either of those conditions has been met…
so the cause for concern is still very low. Now that we know gravitational waves are out there, it
appears highly unlikely that such a world-ending one could ever sneak up on us untracked.
So, while this is still a line of cosmic enquiry that’s very much in its infancy,
and while we do have so much more left to learn about how gravitational waves behave…
there’s no need to overly worry just yet. The universe is immeasurably big, and it’s
constantly rippling with gravitational energy. Space is dangerous and we are vulnerable. But,
still, gravitational waves aren’t an imminent threat… they’re more just another reminder,
against the backdrop of everything, of how small we really are.
What do you think? Is there anything we missed? Let us know in the comments, check out these other
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