What Whathappensify can simulate
Cities connect the physical world with the ways people live. A street carries traffic, brings customers past a shop, helps people reach work and can be difficult for someone to cross. Changing it affects more than one part of daily life.
Whathappensify follows how people, places, resources and infrastructure change and affect one another, from an individual journey to long-term investment and feedback.
Your assistant combines suitable physical models, network analysis and models of stocks, flows and feedback. It can draw on shared models or help you write one, then connect the calculations around the question you want to answer. The simulation method reference gives the equations, techniques, inputs and measures behind them.
A model’s calibration, validation and intended use travel with every result; solving its equations does not by itself establish that it describes a particular place.
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Water comes in from the river and fills the low ground it can reach.
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With nothing in the way, cars still bunch into jams that drift backward.
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Sound fades with distance, and a wall shelters the homes behind it.
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The wind carries smoke from a chimney and spreads it as it goes.
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People heading for one doorway crowd in front of it, then spread out.
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An infection travels between districts with the people who commute.
Questions people can bring
Where should our three pizza shops go so deliveries work on a busy Friday? Which corner fits the hours of a food truck? Where does shade make an afternoon walk possible? How do staffing and opening hours change the queue outside a clinic? Which investment improves access without moving the burden onto another neighborhood?
A useful analysis follows the consequences that matter to the people asking. You can compare alternatives, examine who experiences the effects, question an assumption and develop a different proposal. A model can describe a place, a network or a process such as a budget or a service queue that needs no map.
Environmental conditions
Explore floodwater, outdoor heat, noise and air pollution alongside the people and activities they affect. Follow where water collects, which roads remain usable, how shade moves through the day and how long people spend exposed. Compare an intervention's effects at particular places, over a stated period and for the groups whose circumstances matter.
A park user can compare shaded paths for afternoon exercise. A town can compare shade for people waiting for a bus, then follow how the answer changes as trees grow, surfaces change and maintenance is carried out. Residents can compare flood adaptations and the access that remains during a storm. A market can explore layout, crowd movement and noise together. The result records the supplied conditions and the limits of the model used.
Movement and access
Traffic models follow vehicles, queues, route choices and congestion. Crowd models follow people moving through streets, entrances and shared spaces. Network analysis examines routes, reachable destinations, alternative paths and access to work, food, care and public space.
You can compare individual journeys and the wider pattern: which destinations become easier to reach, who takes a longer route, how departure time changes access and where a disruption spreads. Supplied transit journeys retain their uncertainty and missing connections. A link between two places carries the time, capacity or other meaning actually declared for it.
A transport experiment can connect changes in infrastructure to changes in travel, and feed the resulting conditions back into the next period's demand. Direct effects, effects on nearby places and the total outcome remain distinguishable.
People and services
Stocks and flows describe amounts that build up and run down: people waiting, staff available, food in storage, money in a fund or repairs outstanding. Delays describe how long training, delivery, recovery and other processes take. Feedback connects an outcome to the conditions that shape what happens next.
Your assistant can turn your account of a service into an inspectable model. You can open its diagram, read the equations and units, change a rule, check it and prepare a run in the browser. Real arrivals from a crowd or traffic simulation can feed the service model; the connection keeps the source, conversion and time window visible.
Compare staffing, opening hours or service rules under the same conditions. Follow waiting, completion, resources and exposure through time. Models of infection and contact networks support questions about transmission under their stated assumptions and evidence.
Neighborhoods and economic life
Explore how a change affects opportunities, businesses, households and public services. Network methods describe commuting, skills, specialization, nearby markets and the places groups visit. Economic models compare changes in location, access, prices, resources and government accounts under declared assumptions.
Long-term models follow investment, workforce training, maintenance, wear and replacement. A cooperative can compare retrofit schedules with the workers available to carry them out. A town can examine how a service develops as demand changes. A stock of equipment or material can distinguish what remains usable from what is worn, waiting for repair or replaced.
The same experiment can show a total gain and a loss for a particular group. Its comparisons name whose outcomes are included and which changes count as direct effects or effects on others.
How places and people connect
Networks describe relationships between places, people, capabilities and infrastructure. Explore which connections matter, how a network fragments, where loads pass after a failure and which alternatives remain reachable.
A stated rule can turn a graph with a known source into a stock-and-flow model. The model states what moves, in which direction, at what rate and in which units. A connection alone supplies no physical rate. You can inspect the graph, the mechanism and the quantities passed along each link.
Physical models examine the consequences in space. Stock-and-flow models examine accumulation, delay and feedback. Network methods examine relationships and access. An experiment connects the relevant parts while retaining the meaning and evidence of each.
Change over minutes and years
Some decisions unfold over years but matter during particular hours. A tree grows slowly and changes shade during a hot afternoon. Investment changes a road network and the journeys made on it. Maintenance changes which assets remain usable during a storm.
Whathappensify alternates long-term and event-scale calculations under an explicit exchange scheme. Each model keeps its state and clock, and the experiment states which model changes each quantity. The experiment records when information crosses a boundary, how it is transformed and whether finer calculation or exchange intervals change the answer.
You can continue from a saved state, examine intermediate outcomes and compare a feedback experiment with an otherwise identical case in which that feedback is absent.
Experiments, explanations and learning
Approve a bounded experiment with its alternatives, dependencies, observations and stopping conditions, then watch each run in the browser. The assistant can vary stated parameters, repeat processes that involve chance and compare policy rules under the same samples and conditions. Unsuccessful runs remain visible in the account.
Ask which assumptions influence the result, which feedback loops drive a change and when the dominant mechanism shifts. During replay, follow the dominant loop on the model diagram. A simulated rule states what it observes, when that reading arrives and when its action takes effect. The timeline records each firing, and replay reproduces it. Test zero, large and otherwise demanding conditions against the model's declared expectations. Numerical uncertainty, uncertain inputs, chance variation and uncertainty about the model's structure remain separate.
When a decision could benefit from more information, compare specified observations under the choices, costs and probability assumptions you state. Bring new observations into a model, keeping fitting and independent validation separate and checking what the data can identify.
Combining methods and improving their use
The EPM keeps each conclusion connected to the evidence it depends on.
A completed experiment presents its models, intermediate results, comparisons and readings together. Each keeps its own units, population, time window, assumptions and source. You can follow an answer back to what was measured, what was calculated and what was inferred.
Perspectives connect that evidence to what people value. Read the same result through different criteria, compare who benefits and who bears a burden, and keep concerns visible when a calculation cannot represent them.
Models can be documented, reviewed for a stated use, shared and adapted with their authorship and evidence intact. A scientific review applies to an identified structure, parameters and scope; approval to run an experiment does not supply that review. Shared models, data and experience help the next person begin further along.
Follow one question · Explore imagined uses · Read the technical reference