No, you cannot create energy. This is one of the most firmly established principles in all of physics: energy can change form, move from one place to another, and be converted into matter, but it cannot be created from nothing or destroyed. Every device, organism, and star in the universe operates by converting energy from one form into another.
Why Energy Cannot Be Created
The first law of thermodynamics states that the total energy of a closed system stays constant. Energy going in must equal energy coming out, plus whatever stays stored in the system. This isn’t just an observation from a few experiments. It’s a consequence of something deeper: the laws of physics don’t change over time. The mathematician Emmy Noether proved in 1915 that whenever physical laws have this kind of time symmetry, energy conservation follows automatically. It’s baked into the structure of reality.
This means every machine, reaction, or process that appears to “produce” energy is actually converting it. A gas turbine converts chemical energy in fuel into heat, then into motion, then into electricity. A solar panel converts light energy into electrical current. Your body converts chemical energy in food into motion, heat, and the electrical signals firing in your brain right now. Nothing along the way is being created. It’s all transformation.
What About Nuclear Reactions?
Nuclear reactions can seem like they create energy because the output is so enormous compared to the input material. A nuclear fission reaction, where a neutron splits a heavy atom like uranium into two lighter atoms, releases millions of times more energy per atom than burning coal or gas. Fusion, where two light atoms like hydrogen are forced together to form helium (the process powering the sun), releases several times more energy than fission.
But neither reaction creates energy. Both convert mass into energy. Einstein’s famous equation, E=mc², describes this relationship: a tiny amount of mass, multiplied by the speed of light squared, equals an enormous amount of energy. The total mass of the products after a nuclear reaction is slightly less than the mass of the starting materials. That missing mass is the energy released. The books still balance.
How Your Body Converts Energy
Your cells run on a molecule called ATP, which acts as a universal energy currency. When you eat food, your body breaks down glucose through two main pathways. The first, glycolysis, happens in the main body of the cell and produces 2 ATP molecules per glucose molecule. That’s a modest return. The second pathway, oxidative phosphorylation, takes place in the mitochondria and can produce up to about 31 additional ATP molecules from that same glucose. The total yield tops out around 33 ATP per glucose molecule.
None of this energy is new. It traces back to the sunlight that plants captured through photosynthesis, which built the glucose molecules in the food you ate. The plant didn’t create that energy either. It arrived as light from the sun, where it was released by nuclear fusion reactions converting hydrogen into helium. Every calorie you burn started as mass inside a star.
Why Perpetual Motion Machines Always Fail
Throughout history, inventors have claimed to build machines that run forever without external fuel, effectively creating free energy. None have ever been verified to work. These devices are classified by which law of thermodynamics they violate. “First kind” perpetual motion machines claim to put out more energy than goes in, directly violating energy conservation. “Second kind” machines try to extract useful work by reversing entropy, violating the second law of thermodynamics, which states that energy naturally spreads out and becomes less organized over time.
The second law is why no energy conversion is perfectly efficient. Every time energy changes form, some of it disperses as waste heat. A car engine converts only about 20-30% of the chemical energy in gasoline into motion. The rest becomes heat. Even the most efficient solar cells ever tested top out around 26-27% efficiency for standard single-layer designs. You always lose something in the conversion.
Does the Universe Break Its Own Rule?
There is one place where energy conservation gets genuinely complicated: the expanding universe itself. The accelerated expansion of the cosmos, driven by what physicists call dark energy, presents a real puzzle. Dark energy behaves like a constant energy density filling all of space. As the universe expands and new space appears, the total amount of dark energy increases proportionally to the cube of the universe’s scale factor. Meanwhile, light traveling through expanding space loses energy as its wavelength stretches (this is called redshift).
This isn’t a loophole you can exploit. The issue arises because general relativity, which governs the universe at cosmic scales, doesn’t guarantee energy conservation the way everyday physics does. The time-translation symmetry that Noether linked to energy conservation doesn’t hold in an expanding universe. Some physicists have proposed that the energy gained by dark energy exactly matches the energy lost by light through redshift, preserving a kind of cosmic bookkeeping. But this remains an open question, and it operates at scales so vast it has no practical relevance to anything on Earth.
What We Actually Do With Energy
Since creating energy is off the table, civilization runs on converting it as efficiently as possible from available sources. In 2024, non-fossil sources including nuclear, renewables, bioenergy, and waste grew by over 5% and made up nearly half the total growth in global energy demand. Renewables alone accounted for the largest share of growth in total energy supply at 38%, followed by natural gas at 28% and coal at 15%.
The practical challenge has never been creating energy. The sun delivers more energy to Earth’s surface in one hour than humanity uses in a year. The challenge is capturing, converting, and storing it efficiently enough to be useful, and doing so without the environmental costs of burning fossil fuels. Every advancement in solar panels, batteries, and grid technology is an improvement in energy conversion and storage, not energy creation. The energy was already there.