Science is full of tantalising "What if?" questions.
But until recently they were considered not worth answering. NewScientist Magazine, 20th August 2005
This is a great article, but I found one 'What if?' scenario to be particularly interesting. Snippets included here, the full article is available online here (subscription required).
By Gregory Radick, lecturer in history and philosophy of science at Leeds University, UK
"...Showing conclusively that something happened isn't the be-all and end-all of history. Historians must also try to explain the past. And, whether they like it or not, doing so involves asking and answering "What if?" questions... [Every venture has a flip-side.] Whatever plausible evidence you can produce in favour of the factual claim doubles up as evidence for its counterfactual counterpart."
By A. Bowdoin Van Riper, social and international studies at Southern Polytechnic State University, Marietta, Georgia, USA.
"...Early in the 1820s, Hans Christian Orsted and Andre-Marie Ampere had shown that an electric current moving through a wire generated a magnetic field around the wire. Building on their work, [Michael] Faraday showed in 1831 that the reverse was also true: moving a wire through a magnetic field creates an electric current in the wire...
...Faraday's conceptual breakthrough happened when it did for identifiable reasons. One was the invention of the battery, which could provide a steady flow of electricity. Another was the Romantic movement, which promoted a holistic view of the world that encouraged scientists to consider that seemingly discrete phenomena might be connected. Suppose, however, that a similar set of causes had come together a century earlier... What if electric generators and motors had been on hand before the industrial revolution began?
...The first electric motors would probably have arrived on the market sometime in the 1740s - a time when the steam engine was used only in a few niche applications... Potential users would, therefore, have judged electric motors not against steam engines but against the power sources that had served for centuries: wind and water for heavy-duty work, human and animal muscle for everything else... electric motors would offer obvious advantages - compactness, quiet operation and the ability to work steadily for hours with no need for feed, water or rest. In the 1740s and for decades afterwards, steam engines had none of those virtues and were more expensive to boot. Electric motors would, therefore, have been adopted more widely and more quickly than steam.
The electric motors of the 1740s would have been small enough and quiet enough to operate in a modest-sized workshop. Opportunities to apply them would have abounded... The steam-driven industrial revolution that actually took place in the final third of the 18th Century emphasised centralisation. Even the most sophisticated of steam engines of the time were so large, expensive and fuel-hungry that to use them efficiently, you needed large factories. The electrically driven industrial revolution that might have taken place would, at least at first, have been inherently decentralised...
In our world, the electricity distribution system developed after, and imitation of, the distribution system for natural gas. [Instead] the provision of electricity might have been organised more like the provision of heat, with those in the countryside opting for self-sufficiency while those in the cities could have chosen their supplier from one of several competing neighbourhood sources, as they did for coal deliveries. Small localised power grids might have become the rule, and large, city-spanning ones the rare exception.
The longer-term effects... would have been profound. The spread of electrical lighting and home appliances would have begun earlier. The electrical automobile [may have become] a mature technology before the invention of the internal combustion engine. Gas lamps and stoves would have been still-born... Cities built without networks of gas pipes would have been less prone to burn in the event of catastrophic damage... The absence of a city-wide electrical grid would, in turn, make massive power outages a virtual impossibility..."
There's a lot more information, as well as other scenarios that cover Darwin, Einstein and others (even Hitler), in the full article - recommended reading if you subscribe to the web site/magazine.