Take a modern setting and a character with a good working knowledge of physics and no fear on telling people about whatever supernatural stuff they've found. As the only piece of magic in the setting, suppose that they are given a large branch of wood that burns eternally and produces smokeless but hot fire. Suppose also that this branch's fire can't start other eternal fires, but can start normal ones.

Clearly, this is a source of infinite energy. However, the power is very low. Leaving aside the social implications of discovering what appears to be magic, can something as small as this have world-changing consequences? On one hand, "infinite energy" is setting off alarm bells for me, but on the other, I have no idea how to change the world with something that would take an hour to heat up my bathtub. Am I overestimating the dangers of including such an object?

  • $\begingroup$ Does the log continue to "burn" in vacuum? $\endgroup$
    – Dragongeek
    Sep 5 '20 at 22:00
  • $\begingroup$ @Dragongeek Sure. $\endgroup$
    – J. Mini
    Sep 5 '20 at 23:05

Your log has prevented the heat death of the universe.

That's... kinda a big deal.

Short term, it's a boring form of infinite energy. I see:

  • an increase in thefts and murder as people want the magic log for themselves
  • a town burning down, getting rebuilt, and then burning down over and over,
  • some physicists throwing out their good work

A good steam turbine is 40% efficient at turning heat into energy, and a good seasoned wood log can put out 4kw of heat energy. That's 1.6kw of power for life, I have solar panels on my roof giving me more free power than that.

However in the lifespan of a human, of even the planet, that small amount of power adds so little energy that it can be basically ignored.

Over extreme long term, the universal implications are paradigm breaking.

  • $\begingroup$ How awfully nice for the philosophers... $\endgroup$
    – J. Mini
    Sep 4 '20 at 17:55
  • $\begingroup$ Oh, this is hilarious. +1! $\endgroup$ Sep 4 '20 at 18:51
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    $\begingroup$ It only breaks physics as we know it if it's genuinely eternal. If the log had the half-life of, say, U-238 it would appear as stable as could be on human timescales but would die out well before anything truly bizarre happened. $\endgroup$
    – Cadence
    Sep 4 '20 at 19:15
  • 4
    $\begingroup$ It's also only unlimited if the universe keeps expanding and cooling. A static universe would eventually heat up to the temperature of the log, and it'd stop being a source of usable work. $\endgroup$
    – parasoup
    Sep 4 '20 at 19:29
  • $\begingroup$ Preventing the heat death of the universe is a bit extreme. You would end up with a dead universe and a single stick floating in space that marginally heats the surrounding area and then.... nothing. Ever expanding, ever cooling. $\endgroup$
    – Trioxidane
    Sep 5 '20 at 5:38

The main limitation in usefulness would by that you only have your puny human lifespan to make use of it.

It would tell us a lot more about how the universe works than be useful in its own right...at least until we figure out how to make people live forever with extremely long periods of hibernation for the power to be accumulated somehow. If people lived forever but had no hibernation it still would not be very useful.

And it would not just tell you stuff about energy either. Fact is that all matter decays into iron eventually and if something lasts forever then it must not decay which makes it a research piece about more than just energy.

  • 1
    $\begingroup$ @JBH And the fact that something exists that doesn't decay tells you something about how the universe works. $\endgroup$
    – DKNguyen
    Sep 4 '20 at 18:53
  • $\begingroup$ That's true. I'm just pointing out that it's a temptation to make an OP's universe conform to our own. I do it all the time. $\endgroup$ Sep 4 '20 at 18:58

If this ever burning branch is useless at large power levels required by human activities, it can become really interesting when powering one small thing, such as a space probe.

Combined with a thermocouple it can produce electricity (like radioisotope thermoelectric generators do) for communications, cameras, sensors and everything else requiring electricity.

Mostly it produces photons, that can be directed in one direction, becoming an everlasting photonic thruster. This (very low thrust) would allow the small probe to visit the entire solar system, and thrusting for decades could also allow it to reach ridiculous speed, so that a mission to one of our nearest neighboring star system becomes possible.


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