Unmitigated climate change poses an existential threat to our way of life.
A major economic study projects a long-term 20 percent reduction in global gross domestic product from climate change. To avoid such unprecedented declines, we must reduce our greenhouse emissions in the U.S. by 80 percent by 2050. This goal is realistic, but a major undertaking that requires deliberate action.
Numerous economic models demonstrate that transitioning to renewable energy is likely to result in a net economic gain for our society. That does not mean that every individual will benefit, nor that the transition with be without pain, but it does mean that the transition is likely to result in more jobs and a more efficient and resilient electricity system. A recent study by the Risky Business Project provides a framework for an approach that is both technically and economically feasible. It is based on three principal transitions: shifting from fossil fuels to electricity, generating electricity from low- and zero-carbon sources and using all energy more efficiently.
The shift from fossil fuels to electricity includes the gradual adoption of electric vehicles, electric and geothermal heat pumps, and electricity in industrial processes. The shift to renewable electricity production requires a rapid transition to zero-carbon sources, like wind, solar, geothermal and nuclear, along with an expansion of energy-storage technologies and a redesigned grid to reduce the variability impacts of wind and solar. The potential for increased efficiency in energy use is significant, as we lose about half of all electricity generated in the U.S. to system losses. A redesigned distributed generation grid could dramatically reduce those losses.
The cost of this particular plan would be around $320 billion a year from 2020 to 2050, but the returns over the life of the transition would be substantially larger and would continue indefinitely. The savings would start at around $65 billion a year in the 2020s, increasing to over $700 billion a year in the 2040s. Around 1 million additional jobs would be created during the 30-year transition, with many of the largest gains being in the domestic construction and utilities sectors. While other approaches may offer greater or fewer costs or benefits, the important point is that the renewable energy transition can be a win-win proposition for our economy.
The good news is that physicists have developed complete, tested and verified models of time travel that perfectly explain how objects (including humans!) can, and do, travel through time.
The bad news is that it’s the ultimate one-way street. We constantly are traveling through time, but our velocity in that direction is, with all the unfortunate consequences, unstoppable.
The theories of special and general relativity fully explain the rich physics of how to manipulate the rate at which clocks can tick due to large relative velocities and/or different altitudes — not to mention the even more significant effects of strong gravitational fields or near-light speed travel. It’s unavoidable to draw the analogy between these models and humans’ perception of how quickly time seems to pass; an hour in lecture can seem like a minute or a day depending on your frame of mind.
Understanding time travel, at least in this sense, is more than an academic exercise. The observable consequences of relativity are relevant in many of the processes that we take for granted. For instance, not a day goes by that I don’t rely on my GPS to tell me how long it will take for me to get home. This technology would be useless without a careful understanding of why the clocks on the GPS satellites tick at a (relative) different rate to those we have in our phones.
The great mystery, however, is not the fact that we travel through time in one direction, but rather why we travel in one direction. Macroscopic physics — thermodynamics, to be exact — dictates the rules that compel us forward, and forbid us to travel backwards, through time. On the other hand, microscopic physics has (almost) nothing to say about the choice of early versus late or young versus old. All microscopic laws of physics are time-reversal symmetric, meaning that these laws don’t care if time goes forward or backward. The origin of the arrow of time, the principle that dictates that we bleed after we’re cut, is an open question in physics.
In short, we’re great at time travel; we know a lot about how time works and have harnessed its power in multiple ways. The limitations of this model that get us down, but these same limitations help our GPS get us to where we need to go.