Captain Michael Burnham and her time-hopping crew seem pretty certain The Burn is no longer a threat in Star Trek: Discovery season 4 - but are they right? Jumping 900 years into the future thanks to Spock, the Red Angel and an evil AI program, the Discovery crew might've hoped to find a utopia honoring Gene Roddenberry's original Star Trek vision. Instead, Sonequa Martin-Green and the gang were greeted with a post-apocalyptic galaxy decimated by a mysterious event called The Burn, where all dilithium (the stuff powering virtually every space-faring vessel in operation) suddenly and simultaneously imploded.
Star Trek: Discovery's heroes spent season 3 figuring out what caused The Burn, and stumbled across a massive source of dilithium in the process, ensuring a brighter future for the Federation & friends. Indeed, everyone seems confident The Burn won't happen again when Star Trek: Discovery season 4 begins. Burnham and Booker reassure a planet of butterfly people that those dark, dilithium-less days are over, while Saru comforts the skeptical folks of Kaminar that The Burn isn't getting a sequel.
The final episodes of Star Trek: Discovery season 3 explained how The Burn was caused by a young Kelpien called Su'Kal. Still pregnant with her son, Su'Kal's mother crash-landed on a dilithium rich planet sitting at the heart of a nebula, and the unborn Kelpien attuned to his unusual surroundings while developing in the womb. Watching his mother die from radiation poisoning some years later, Su'Kal's emotional outburst created a devastating resonance that ignited dilithium across the galaxy - a moment later known as The Burn.
Admittedly, it's easy to see why Star Trek: Discovery's Michael Burnham and Saru are so confident The Burn won't happen again in season 4. The original event was a freak accident that required an incredibly specific set of circumstances - a planet stuffed to the brim with dilithium, a radioactive space nebula, a pregnant mother, and a tragic accident. The incident was so unlikely, almost a millennia of Burn-free space travel passed before Su'Kal dealt the Federation a blow Star Trek's worst villains can only a dream of. It's almost impossible the stars will align for Burn 2: Dilithium Boogaloo, especially since the Federation will now be incredibly wary of pregnant women crashing on inescapable dilithium goldmines.
Unfortunately for the Star Trek: Discovery gang, there's a considerable "but" to their assurance The Burn won't happen again. That it happened once - and by coincidence, rather than design - proves a second Burn is scientifically possible, albeit extremely remote. Star Trek: Discovery season 3 confirmed a Kelpien in utero can psychically bond with dilithium and trigger a chain reaction under the right conditions. What happened to Su'Kal could, in theory, happen to another child in the future. Even more concerning, if the cause of The Burn became public knowledge (and with Kaminar and the Federation both already in the know, it's hardly a secret in Star Trek: Discovery season 4) Starfleet's enemies could even attempt a second burn deliberately.
Saru's confidence that The Burn was a one-and-done cosmic tragedy could be attributed to 2 mitigating factors. Theta Zeta (the dilithium planet The Burn emanated from) is probably the only location of its kind in the charted galaxy and, therefore, the only place another Burn could happen within a range that actually impacts Federation space. Secondly, Star Trek: Discovery season 4's premiere reveals research is being undertaken into alternative fuel sources similar to the Discovery's own spore drive. This means Starfleet need only guard against another Burn a few more years before ships are no longer dependent on dilithium. Only then will the chances of another Burn truly get the redshirt treatment.