Energy Disappears in an Expanding Universe

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In an expanding universe, the traditional concepts of time invariance and energy conservation become compromised. Unlike in special relativity where space-time is flat and symmetrical, general relativity presents a lumpy space-time influenced by mass. This curvature, along with expansion, results in non-equivalent reference frames that affect how we compare the universe at different times. Consequently, energy appears to disappear, exemplified by redshift phenomena where long wavelength light, traveling vast distances, shows reduced energy, akin to the Doppler effect. Observations of distant astronomical events like quasars and supernovae illustrate this energy loss, challenging the notion of global energy conservation in the context of an expanding universe.

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How much energy is needed for GDP growth? Would our civilization have developed at the same rate without fossil fuels? Could we potentially do the same things we're currently doing but with significantly less energy? How different would the world look if we'd developed nuclear energy much earlier? Why can't anything go faster than light? Will the heat death of the universe really be "the end" for everything? How can difficult concepts be communicated in simple ways that nevertheless avoid being misleading or confusing? Is energy conservation an unbreakable law? How likely is it that advanced alien civilizations exist? What are S-risks? Can global civilizations be virtuous? What is panspermia? How can we make better backups of our knowledge and culture?

Anders Sandberg is a researcher at the Institute for Futures Studies in Sweden. He was formerly senior research fellow at the Future of Humanity Institute at University of Oxford. His research deals with emerging technologies, the ethics of human enhancement, global and existential risks, and very long-range futures. Follow him on Twitter / X at @anderssandberg, find him via his various links here.

Staff