Science-based hypothetical scenarios
What would actually happen if…?
Explore science-based "what if" scenarios with real physics, timelines, and survival outcomes.
Pick any hypothetical — the Moon disappears, gravity doubles, a pandemic starts differently — and read a step-by-step breakdown of exactly what would unfold, from the first seconds to civilisation-scale collapse.
Most people don’t expect what happens next.
Create your own scenario
Start with one change. See how everything unravels.
What is WhatIfEngine?
WhatIfEngine is a science-based Q&A site for hypothetical questions. Every article answers one question: what would actually happen if…? — grounded in real physics, biology, chemistry, and history, not guesswork.
Each answer is structured as a timeline of consequences: what happens in the first seconds, what cascades over the following hours and days, and what the long-term impact looks like for climate, ecosystems, civilisation, and human survival.
Browse questions others have already explored below — or submit your own "what if" using the form above.
Latest explored scenarios
What If Humans Tried to Live Forever in Sealed Habitats?
Can humans live long-term in sealed habitats? Practical science, likely failure modes, and what it would take to make sealed life sustainable on a generational scale.
Living Below: Could Humans Live Underground or Underwater Indefinitely?
Could humans live indefinitely underground or underwater? Explore the physics, biology, timelines, and practical survival strategies for long-term life below the surface.
What If Engineers Protected Cities from Permanent Flooding?
How would engineers actually protect cities from permanent flooding? A clear look at barriers, pumps, wetlands, retreat, and what residents must do to survive and adapt.
What If Continuous Rainfall Caused Global Crop Failure?
If rainfall never stops, fields waterlog, seeds rot, and harvests fail. How would food systems cope, what science explains the damage, and how could societies survive?
What If Nonstop Rain Raised Sea Levels?
If rain never stopped, would the oceans rise? Explore the physics, plausible timelines, likely impacts on cities and ecosystems, and practical steps for survival and adaptation.
If the world became perpetually wet, which animals would win?
If the planet turned perpetually wet, amphibians, aquatic birds, fish, crustaceans, and wetland mammals would be the big winners. Read how ecosystems would reshuffle, timelines of impact, and what humans would need to do to survive.
What If Animals Learned to Use Roads and Elevators?
Urban wildlife starts using roads and elevators. What changes, who wins, who loses, and how cities adapt. Practical steps for safety and policy, and what science says.
What If an Urban Animal Invasion Spread Diseases?
If cities were overrun by animals, which diseases would spread, how they would transmit, and practical steps individuals and public health systems could take.
What If Movies and Games Were Replaced by Practical Hobbies?
Swap passive screen time for practical hobbies. Learn which hands-on activities can replace movies and games, how adoption unfolds, the science behind the switch, and practical steps to make it stick.
What if the entertainment industry vanished: would art disappear?
If the entertainment industry vanished, art would not die but it would shrink and change form. What would vanish, what would adapt, and how could communities save culture?
What If Play-Based Media Disappeared?
What happens if all play-based digital media disappear overnight? Explore the immediate shocks, shifts in education and culture, the science of play, practical survival steps for parents and policymakers, and which skills would be at risk.
What If Governments Eliminated Entertainment?
If governments banned all entertainment, social life and economies would shift fast. Short-term unrest, underground culture, and long-term creativity losses are likely. Practical survival and adaptation strategies explained.
What if humans aged very slowly?
What if humans aged very slowly? Explore biological paths, social fallout, policy moves and practical survival steps for individuals and societies.
What if People Lived to 200: How Society Would Adapt
Explore how 200-year human lifespans would reshape work, family, politics and the planet, and what policies would help societies adapt.
What If Humans Suddenly Lived to 200 Years?
What if humans suddenly lived to 200 years? How would biology make it possible, what breaks first socially and environmentally, and what practical moves will help us survive the shock?
What If Humans Stopped Reproducing?
A clear, no-fluff look at what would happen if humans stopped reproducing: timelines, technical realities, ecological effects, and what could be done to preserve the species or the knowledge needed to try.
No New Children: How Long Would Humanity Survive?
If births stopped tomorrow, human extinction would be a matter of decades, not millennia. A clear timeline of collapse, societal effects, and what can be preserved before the last generation dies.
What if social systems had to cope with an aging-only population?
What happens when births vanish and societies age? A practical map of policy, technology, and social shifts that let communities cope with an aging-only population.
What if humans relied only on stored reserves?
If humans stopped producing new goods and lived only on stored reserves, how long could we last, what would break first, and how do you stretch what remains?
What If Global Food Systems Were Disrupted?
What happens if global food systems fail? Explore timelines, the science behind the shocks, and practical steps households, cities, and governments can take to survive and adapt.
What Policies Could Prevent Global Food Collapse?
A practical policy blueprint to prevent global food collapse: short-term stabilization, mid-term production shifts, long-term decarbonization and governance. What to act on now.
What If Scientists Bred Disease-Resistant Bananas?
If scientists bred disease-resistant bananas, would global supplies stabilize or spark new risks? A clear scenario explores the science, rollout timeline, likely outcomes, and the agricultural practices needed to keep resistance working.
What if the World's Bananas Collapsed?
If the world's bananas collapsed, grocery shelves would change, tropical economies would suffer, and decades of breeding and biosecurity would be needed to recover. Here's what would happen and how we cope.
What If Private Cars Were Banned Permanently?
A permanent ban on private cars would reshape cities, health, jobs, and the climate. Here are the timelines, scientific trade-offs, and how people would adapt.