Suppose that a scientific breakthrough leads to the discovery of a new cheap source of energy. What would be the effect of this invention in the short-run and in the long-run?

The discovery of a new cheap source of energy could have significant effects in both the short-run and the long-run.

In the short-run:
1. Lower energy costs: The immediate effect of this breakthrough would be a decrease in the cost of energy production, which would benefit industries and consumers. Reduced energy costs could lead to lower prices for goods and services, resulting in higher purchasing power for individuals.

2. Increased investment and economic growth: With access to a cheap source of energy, businesses may be more inclined to invest in energy-intensive industries such as manufacturing, transportation, and construction. This increased investment can stimulate economic growth, generate job opportunities, and ultimately improve living standards.

3. Environmental implications: Depending on the nature of this new energy source, there could be environmental repercussions. If the source is renewable and has low carbon emissions, it could contribute to a reduction in greenhouse gas emissions and help mitigate climate change. However, if the energy source is not sustainable or has negative environmental impacts, it could exacerbate environmental problems.

In the long-run:
1. Energy independence: Discovery of a new cheap source of energy could reduce dependence on fossil fuels and foreign energy sources. This enhanced energy independence can provide greater control over domestic energy production and increase national security.

2. Technological advancements: The availability of cheap energy can catalyze technological advancements in various fields. Researchers and engineers may be inspired to develop more energy-efficient technologies, explore alternative energy storage solutions, or innovate in other areas to capitalize on the newfound energy source.

3. Energy transition: In the long-run, the discovery of a new cheap energy source may lead to a transition away from fossil fuels, which have numerous environmental and sustainability concerns. This transition could contribute to a cleaner, more sustainable energy system and reduce overall carbon emissions, thereby mitigating climate change.

It is important to note that the specific effects will depend on the characteristics of the new energy source, the scale of its implementation, and the policies and regulations surrounding its adoption.