At the big bang, matter formed from the initial energy when it cooled enough for particles to form. But how was space formed?
Chris Daniel
Glan Conwy, UK
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Space began in the first 10-35 of a second after the big bang, when the universe was thought to have been smaller than an electron, but then expanded rapidly, according to the widely accepted theory of cosmic inflation.
At that time, the universe consisted of a soup of particles, antiparticles and photons as well as anything else that could exist in the unimaginable temperatures of around 1022 kelvin. Particles collided, sometimes annihilating each other and sometimes creating new types of particles as the universe continued to expand, but at a much slower rate than the initial cosmic inflation.
In the first fractions of a second after the big bang, protons and neutrons formed, and not long after, they coalesced to form hydrogen and helium nuclei. After 300,000 years, electrons were captured to form atoms of hydrogen and helium. Another 80,000 years later, they left behind photons, which filled space and which are detectable today in the form of microwave background radiation. As the universe continued to grow and cool, the distances between particles increased, and the collisions between them became less frequent.
Even now, the so-called vacuum of space isn't empty. It continues to teem with particles such as hydrogen and helium atoms
Even now, the so-called vacuum of space isn鈥檛 empty. It continues to teem with particles such as hydrogen and helium atoms, cosmic dust, mostly carbon and silicon, from planets and stars. Space is also permeated by gamma rays and X-rays from supernovae, gravitational and magnetic fields from stars and planets, plus the microwave background radiation. Unseen dark matter is likely to account for much of the universe鈥檚 mass, while dark energy may be driving its continual expansion. Space 鈥� the gaps between particles, planets and galaxies 鈥� is simply a consequence of the energy that powered and continues to power the growth of the universe.
Dave Rowsell
Gowerton, Swansea, UK
In short, we neither know nor truly understand how space was formed. As I see it, space (or better, space-time) either formed at the big bang or it didn鈥檛. If it arose from a point singularity, relativity theory predicts this point would have started off with infinite density, thus curling space-time so tightly it wouldn鈥檛 have existed. In this scenario, the big bang created space-time.
We should also ask, if space-time is expanding, what is it expanding into? A balloon expands to take up more of the space around it. But that can鈥檛 apply to a universe that contains space. On the other hand, if the universe didn鈥檛 originate from a point singularity, but from something very close to it, it would have had a measurable size and hence must have occupied space-time. Then the big bang would have occurred within a pre-existing continuum, which means that our universe is contained within a possibly infinite and eternal space-time. In this case, is the universe wrongly called the multiverse? To make matters worse, the famous twin paradox complicates it further. This concerns time dilation. One twin is sent on a space journey at close to the speed of light. After the twins reunite, they would each have a different but 鈥渙bjective鈥� calculation of when exactly the big bang happened. All of which leads me to wonder that perhaps the question is wrong, and we are caught in an infinite regress.
Pat French
Longdon Upon Tern, Shropshire, UK
The answer to this question very much depends upon the definition of space. The word is used in many ways. For instance, outer space is said to start beyond the K谩rm谩n line, an imaginary boundary 100 kilometres above Earth鈥檚 surface.
If we take space to mean the volume occupied by the universe, then this is the entity within which we commonly experience four dimensions. Along with length, width and height (that make up volume), we experience time. These four dimensions together make up the fluid space-time continuum known as Minkowski space.
If space is defined as the volume occupied by the universe, it would seem reasonable that space came into existence at the moment in time when the universe extended beyond its big bang singularity.
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