Deadliest Things in Our Universe

Alejandra Miranda
7 min readMar 8, 2022

*Disclaimer: This piece was redacted in a humorous fashion given the fatalistic premise of its topic. What fun is there in being an astrophysicist if you cannot laugh at wacky (but plausible) scenarios anyways?

Extra extra! Buy your intergalactic newspaper now! With its front-page headline:

Top 5 Deadliest Things in the Universe!

Presented as a list, the bodies and spatial phenomena mentioned are of great magnitude and capable of immense destruction. These are so destructive that they can end life as we know it. For this reason, I am sure that at least one of you will end up shouting “The apocalypse is coming!” after reading. And if you do not believe me, wait till you see number 2.

Without further ado, I introduce you to these cataclysmic events!

Number 5: Rogue Black Holes

Kicking off our list are these colossal regions of space-time. Black hole’s biggest asset is to offer great vacation deals for anything seeking a one-way trip to nowhere. This ability stems from their gravitational pull, which is so strong that nothing (including particles and even electromagnetic radiation such as light) can escape beyond its event horizon.

Sadly, these massive vacuums are not easily detected given the vast darkness of space, meaning that hundreds of them may be lurking about without us even knowing. But what might be spookier than that is learning that some of them might be capable of movement.

Better known as rogue black holes, these stellar remnants are cosmic regions whose size is around 600 million solar masses. Their formation occurs during galactic collisions when the impact of two galaxies throws them out into outer space spinning at speeds as fast as 9.5 million km/h. In short, these kinds of black holes are invisible, fast, humongous, and capable of sucking in, literally, everything. And that includes you, me, the neighbour’s dog, and whatever else there is within the observable Universe.

Number 4: Galactic Cannibalism

If you thought that cannibalism only existed on Earth, you are very wrong. In our Universe, certain galaxies happen to have “peculiar” eating habits. These colossal and gluttonous systems like to “consume” smaller galactic bodies, giving rise to an event known as galactic cannibalism.

This process occurs when two galaxies merge during a cosmic collision. Generally speaking, a large galactic body fuses with a tinier companion through tidal gravitational interactions, yielding a grander, often irregular, galaxy. Such a formation is a beauty to behold, but do not let that fool you for long since this is a tremendously destructive event. Many planets found within each system get thrown out into space, where, if unlucky, they could get pulverised by hypervelocity stars [1]. So, although it might be a spectacle to witness, it is best to be as far as possible from any galactic collision. Otherwise, we might end up getting hit by some errant planet.

Interestingly enough, our very own galaxy arguably practices galactic cannibalism. It has been suggested that the Milky Way is currently “devouring” the Large and Small Magellanic Clouds since there seem to be streams of gravitationally-attracted hydrogen arcing from these dwarf galaxies towards us. But even if that was not the case, our galaxy will get to feast on Andromeda at some point. By our estimates, in around 3,000 million years or so. I guess one could argue that the Milky Way will be starving by then.

Number 3: Magnetars

A neutron star is an incredibly dense stellar object whose mass is compressed into an area of ​​at least 15 km. Translated into common parlance, what this means is that it is an incredibly hefty body. To offer a little perspective: just one teaspoon of their material would weigh about 10 million tons! [And here I was assuming that my Physics books were the heaviest things in the Universe.]

Now, a magnetar is a type of neutron star that has a diameter of 20 kilometres (12 mi) and a mass of 1.4 solar masses. It is formed due to the collapse of a regular star into a neutron one during a supernova. When this ensues, the star’s magnetic field increases dramatically in strength through the conservation of magnetic flux.

Thereafter, if the spin, temperature and magnetic field of the recently shaped neutron star fall into the right ranges, a dynamo mechanism could get activated. Such a mechanism would then convert heat and rotational energy into magnetic energy, increasing the star’s magnetic field and, thus, producing a magnetar.

And a magnetar’s magnetic field is something that you would not want to mess with. It is presumed that its magnetic field is extremely powerful and that its decay powers the emission of high-energy electromagnetic radiation (particularly X-rays and gamma rays). That indicates they are strong enough to perturb the molecular structure of an object and, therefore, dissolve it.

As such, if we were to be hit by one of these loaded friends, our composition of 60% water will turn us into a soup of hydrogen, oxygen, carbon, and other elements. And that does not sound tasty at all.

Number 2: Gamma-ray Bursts

Gamma-ray bursts (or GRBs for short) are immensely energetic explosions capable of lasting from ten milliseconds up to several hours. As observed in distant galaxies, their intense radiation is likely released when a high-mass star implodes into a supernova, or a superluminous supernova, to generate a neutron star or a black hole.

Accordingly, this occurrence offers a dazzling sight that exhibits all sorts of sparkling colours to the naked eye. It is then easy to understand why gamma-ray bursts are considered the most energetic and luminous electromagnetic events since the Big Bang. Unfortunately, appearances are highly deceiving because these emissions are very lethal. These are radiation flashes, after all. Ergo, they are anything but “life-friendly” energy emissions.

In fact, gamma-ray bursts are highly effective at destroying habitable planets. They are the cause behind the mortality of entire ecosystems through the devastation of atmospheric systems. And tragically enough, this issue brings about massive extinction events that could potentially eradicate all life.

That said, it might be relevant to point out that there is no record of an extinction event caused by these outbreaks. At least for now. So let us brace ourselves and hope that our species does not end on a whim due to them.

Number 1: Hypernovae

And in our number one spot, we find hypernovae. As its name implies, a hypernova is conceptually similar to standard supernovae. There are some substantial differences between them, though. A supernova, for instance, is the catastrophic explosion of a massive star. On the other hand, a hypernova arises when the core of a supermassive star collapses into a rotating black hole. As the energy of this explosion is released, jets of plasma move at the speed of light and emit gamma radiation (an event that you can picture as a sort of cosmic cannon).

Essentially, these are the product of supermassive stars that choose “to die with passion”. And hey, if impending death is coming, it better be of epic proportions by universal standards, am I right? But alas, this case of exceptional nova is a wombo combo that maximises a death star’s potential for disaster.

On this account, it is relevant to note that the responsibility behind the two largest mass extinction events in the history of the Earth [2] is attributed to hypernovae. So under our current score, hypernovae are technically more harmful than gamma-ray bursts. But one must never forget that both of these explosions share the same mission either way: the massive extermination of biodiversity.

And that was it, folks.

Oh, but wait.

There is one more deadly universal thing that I must mention before giving an end to this piece. Thus, last but not least:

Number 0: The Universe

Yes, the Universe is the deadliest of things found within itself. A kind of paradox, I guess. But how could this be?

Well, if you think about it, the Universe is, quite literally, an immense, [arguably] infinite and [mostly] inhospitable vastness of space-time that contains billions of stars, galaxies, and the hubbub brought about by humans. Sadly, despite being the embodiment of everything that exists, it seems to treat itself and all the matter within with cold indifference.

The Universe does not even care if everything gets liquidated. It is governed by natural laws that allow the astronomical objects that have been grouped in this list to freely transit space. And if you also include the different theories regarding the ultimate fate of the Universe, it is no longer silly to think that the “grand scheme of things” is also their “grand exterminator”.

Fortunately, the situations described above (as well as the theories regarding how the Universe might “die”) will not come to pass for, at least, a few more million years. And by then, if we are lucky enough to still be around as some form of evolved Homo species, I am sure there will be “bigger problems” for us to face.

Thank you for reading. (:


[1] Star that moves at speeds exceeding 1.6 million km/h.

[2] See: New Theory for What Caused Earth’s Second-Largest Mass Extinction.



Alejandra Miranda

Spreading words with a sprinkle of fairy dust and, arguably, some science.