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Simulating...

You made a universe!


You are looking at the dark matter evolve in your simulation from the beginning of time until the present day. This simulation is 40 million light years across each side. Dark matter is the material that dominates the gravity of the Universe and determines the overall structure or "framework". As time evolves dark matter clumps together by gravity to form larger structures (haloes) which eventually will be where galaxies form. Look at the simulation to see the number of big and small dark matter haloes (bright yellow regions). Getting the relative numbers of big and small haloes correct is a crucial test of simulations.

You are seeing the dark matter in your simulation at the present day. This is designed to be viewed with a pyramid hologram projector. If you have a pyramid projector and you are viewing this on your phone then select "hologram video" and play in full-screen mode. You need to make sure that your phone is playing the movie horizontally (i.e., hold the phone in front you horizontally before laying it flat). The holograms look best in a dark room with the phone brightness on full (see here for an example of how to use your pyramid).

You chose a high percentage of dark matter which is how it is in the real Universe is. The gravity from dark matter is good at holding on to gas, which would otherwise be ejected by exploding stars or the energy released by supermassive black holes. About 84% of all matter in the Universe is thought to be dark matter.

Take a look at the gas


You are looking at the gas evolve in your simulation from the beginning of time until the present day. This simulation is 40 million light years across each side. Gas (mainly hydrogen) is the ingredient which stars are made from. Here, the hottest gas is represented by red colours and the coldest gas by blue colours. When gas falls onto galaxies due to gravity it may form stars. However, if lots of energy is blown into the gas from exploding stars or supermassive black holes it doesn't get chance to form new stars before getting too hot or being blown away. Correctly reproducing the right number of galaxies with both lots of and a few stars is a key test for simulations. A key part of this is understanding how much energy is blown into the gas by exploding stars and supermassive black holes. Look out for the hot (red) bubbles in your simulation that are due to exploding stars or powerful supermassive black holes.

You are seeing the gas in your simulation at the present day. This is designed to be viewed with a pyramid hologram projector. If you have a pyramid projector and you are viewing this on your phone then select "hologram video" and play in full-screen mode. You need to make sure that your phone is playing the movie horizontally (i.e., hold the phone in front you horizontally before laying it flat). The holograms look best in a dark room with the phone brightness on full (see here for an example of how to use your pyramid).

You chose a medium level of black hole power which is correct for our model. The energy from black holes helps control the rate at which stars can be created in galaxies by heating and/or removing gas. If this had been too low, you may create too many galaxies with lots of stars. If this had been too high, you may create too few galaxies with lots of stars.

What do the stars look like?


You are looking at the stars evolve in your simulation from the beginning of time until the present day. This simulation is 40 million light years across each side. If gas is able to cool enough to clump together, stars will form. Some of the galaxies in your simulation may contain lots of stars and some may contain only a few stars. Getting this right is a key test of simulations. If the balance of gravity (mainly due to dark matter) with energy injection (from massive stars and black holes) is incorrect the simulation will fail to get these numbers right.

You are seeing the stars in your simulation at the present day. This is designed to be viewed with a pyramid hologram projector. If you have a pyramid projector and you are viewing this on your phone then select "hologram video" and play in full-screen mode. You need to make sure that your phone is playing the movie horizontally (i.e., hold the phone in front you horizontally before laying it flat). The holograms look best in a dark room with the phone brightness on full (see here for an example of how to use your pyramid).

You chose a low level of massive stars which is correct for our model. Large stars live short lives which end with violent explosions known as supernovae. These explosions control the rate at which stars can be created in the future in their galaxies by removing/heating some of the gas.

The biggest galaxy in your Unvierse


This video works with the hologram projector given out at the Galaxy Makers exhibition. You can find a little tutorial on how to use it here.

'Would galaxies form differently in a different Universe? With simulations we can not only learn from modelling our cosmos, but also from modelling one where the underlying physics are changed. This can tell us about what processes were important to form the real galaxies we see through telescopes.

Our galaxies are created in simulations with differing physics - the power of black holes, the size of the stars that form and the amount of mysterious dark matter are all varied. We focus on the same galaxy in each simulation to see how changing the physics alone makes a difference.

These movies show the different galaxies as they would appear through a telescope. We have modelled the light given off by each galaxy using the ages, chemical make-up and mass of stars. You can see populations of young, hot stars as blue in colour, while older populations appear yellow or red. You might also notice how the shape and structure is different in each galaxy - there are compact blobs, messy clouds, flat discs and many more. Changing the physics can make for some very strange galaxies!'

Your score!

Your score is: 20/100


You chose a high percentage of dark matter which is how it is in the real Universe is. The gravity from dark matter is good at holding on to gas, which would otherwise be ejected by exploding stars or the energy released by supermassive black holes. About 84% of all matter in the Universe is thought to be dark matter.


You chose a medium level of black hole power which is correct for our model. The energy from black holes helps control the rate at which stars can be created in galaxies by heating and/or removing gas. If this had been too low, you may create too many galaxies with lots of stars. If this had been too high, you may create too few galaxies with lots of stars.


You chose a low level of massive stars which is correct for our model. Large stars live short lives which end with violent explosions known as supernovae. These explosions control the rate at which stars can be created in the future in their galaxies by removing/heating some of the gas.

Thanks so much for taking part in the Make a Universe exhibit.

On the next page you will find extra information about your Universe and on the page after that some interesting links if you want to find out more. Thanks again!

The Galaxy Makers Team

Extra Information

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Here's some much more detailed information about your simulated Universe.



Most large galaxies are thought to host a supermassive black hole. These are the largest known black holes and range in mass from hundreds of thousands to billions of times the mass of the sun. While the ‘blackness’ of black holes means that we cannot see them directly, the gravity from black holes attracts surrounding gas and dust which heats up as it is pulled inwards. This hot material glows brightly in X-rays allowing us to find these black holes using X-ray telescopes.

Our own galaxy, the Milky Way, has a supermassive black hole known as Sagittarius A* at its centre. From looking at the motion of stars in orbit around this black hole it is possible to calculate its mass, which is thought to be about two million times the mass of the sun.

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Galaxies come in all different shapes and sizes, from dwarf galaxies that may host only a few thousand stars and spiral galaxies like our own Milky Way, to giant elliptical galaxies that can contain trillions of stars.

One of the hard bits when determining the size of galaxies is that they do not have well defined boundaries. Moving away from the centre of a galaxy the density of stars drops without any abrupt edge. A common definition of the size of a galaxy (and that used here) is the half-light or ‘effective’ radius. This is the distance from the centre of the galaxy that contains half of the galaxy’s stars.



Much like the planets of our Solar System orbit the sun, stars move around within galaxies. Our own star, the sun, takes roughly 230 million years to orbit our galaxy, which means that at the start of the Cretaceous period (when dinosaurs roamed) the Earth was on the other side of the Milky Way!

The speed at which stars move around within a galaxy tells us about the gravitational forces acting on the stars. The stronger the gravity, the faster the stars move. Measurements of the speed of stars moving within galaxies have found that the gravitational forces must be larger than what we would expect to be produced by all the material we can see. This provided some of the first evidence for unseen material that we now call ‘dark matter’.

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