
On the anniversary of 9/11, many have been debating a simulation of the attack online, which appears to show how the World Trade Center's Twin Towers collapsed after being struck by two planes.
25 years ago today on 11 September, 2001, two passenger planes entered New York City after terrorists hijacked four planes in the US in a plot to destroy major US landmarks.
The first two hijacked flights hit the Twin Towers, the third flew into the Pentagon in Washington D.C, and a fourth aircraft was brought down in a field in Pennsylvania thanks to the bravery of its passengers.

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Since that fateful day, which saw 2996 people die in the towers, in the planes and on the ground, people have openly debated whether it was an 'inside job', with some speculating that passenger planes couldn't be enough to bring down two giant skyscrapers.
So, to settle the argument after 25 years and on its 25th anniversary, a YouTube channel by the name of Kostack Studio, had one of its many simulations shared online.
This one was of the Twin Towers, showing how they fell after creating a simulation without the smoke and debris clouding what people can see.
Sharing the footage to X, a user wrote that it allows people to see just how it all happened, and also why it wasn't a 'controlled demolition' or inside job, per many theorists online since the event 25 years ago.
They wrote in the lengthy post: "I find these World Trade Center simulations by Kostack Studio fascinating because they remove the smoke and let you see the collapse much more clearly. In the real footage, so much is hidden by fire, dust, debris, distance, and chaos that many people come away with the impression that the towers simply dropped straight down into their own footprints. But that is not really what happened."
What it showed was the South Tower appearing to break near the top and angle itself, before the top floors collapsed into the levels below.
After watching the clip, many were quick to reveal how helpful it was to see in a behind-the-scenes format.
One person wrote: "What i find useful when talking about a controlled demolition is to actually look at a controlled demolition. You can see the flashes of explosives around the entire structure before it begins to fall. None of that is present in 9/11."
Another said: "Decades of outlandish theories dismantled simply by dusting off the image to show gravity doing its job."
But not everyone was convinced by the simulation.
One X user wrote a list of questions they had after viewing the material, writing: "The problem is--the rubble pile wasn't that high. None of those super long beams were ever recovered. Not a single toilet was found. Lots of unburned paper, though. Where did all of the glass go? How come the seismic readings were consistent with something heavy being lifted off of the ground instead of something heavy slamming into it? Why did the Slurry Wall stay intact after two 500,000 ton buildings supposedly smashed into it but bulldozers couldn't drive on the surface because they were damaging the wall? And the toasted cars? And building 7?"
Another claimed: "Jet fuel cant melt steel beams."
Someone else said: "You do realize these towers were engineered to withstand multiple plane impacts from larger and more robust planes right?"