If energy cannot be created or destroyed, where does it come from? (2024)

Herman D’Hondt

Sydney, New South Wales, Australia

It may sound incredible, but many scientists believe that the total energy of the universe is zero. Hence, no energy needed to be “created” when the universe came into existence.

While it seems obvious that there is a huge amount of energy in the particles and radiation that pervade the universe, this energy may be balanced by negative energy caused by the gravitational attraction between the particles. As Stephen Hawking explained, when you pull two objects apart, you need to expend energy to overcome the gravity that pulls them together. As it takes positive energy to separate them, gravity must be negative energy.

If that theory is correct, then there was never any need to create energy or matter – they cancel each other out. That implies that the big bang could have started as a simple statistical fluctuation.

It also means that it may be possible to create our own big bang: just squeeze some vacuum in the right direction and bingo, a new universe, no energy required.

Mike Follows

Sutton Coldfield, West Midlands, UK

Energy can be transferred between different stores. Energy and matter are equivalent, so nuclear energy, for example, starts off as matter. When an inventory is taken of all the matter and energy in the universe, it adds up to zero, which seems counter-intuitive to say the least.

The zero-energy universe hypothesis is the simplest explanation of this, as outlined in 1973 by Edward Tryon, who was the first to suggest that our universe is the result of a quantum fluctuation.

According to Albert Einstein, mass and energy are equivalent and, according to Tryon, the positive energy associated with mass is counterbalanced by gravitational potential energy, which is negative. Also, according to quantum field theory, particles routinely pop into and out of existence. Tryon suggested that the same could happen for a universe.

Keith Ross

Villembits, France

The amount of energy/matter in the universe is constant and derives from the mysterious big bang. Over time, this becomes more and more spread out and less and less useful, even though the actual amount doesn’t change.

Take the sun as an example. Its nuclear fusion reactions turn matter (think of it as concentrated energy) into visible sunlight and other forms of energy. The sunlight hits a green leaf on Earth and the solar energy is now transferred into a chemical energy store as oxygen is separated from carbon dioxide and water, leaving carbohydrate in the leaf.

We eat the leaf and breathe in the oxygen. The respiration reaction in our muscle cells allows the energy to be used to move our arm as we hammer in a nail. The arm, nail, hammer and the air absorb the sound, get hot and radiate infrared heat to outer space.

So the energy concentrated in the original hydrogen atoms in the sun is now scattered into the universe. Low-grade and almost useless, but still the same amount we started with.

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