The Universe in 4D

This series of slides is from my talk, ‘The universe in four dimensions’. This is a big slide show where we see perspective views of the solar system, the stars, the Milky Way, and far galaxies. The talk is illustrated with many computer generated simulations.

Those consisting of red and green dots should be viewed with red and green stereo glasses. (Red over the left eye.) The dots represent stars in the first group, and galaxies in the second. The stars are constellations down to magnitude 9 (naked eye visibility is magnitude 5 or 6). The field of view of each frame about 30°, covering in the case of stars, whole constellations, as visible from Earth. About 70% of people can manage to see the images in stereo. It is best to focus on the screen but try to allow one's eyes to converge in front of it, where the stars will appear hanging in space. A little practice may help. It also works fine when projected onto a large screen and is not critical of the viewer's location.

I took a celestial Star map database of stars which included absolute and apparent magnitudes, which enabled me to get distance. These were converted into an XYZ Cartesian grid. Added to this was the star's velocity information, allowing time to be moved forwards or backwards to their location at any given time. The observer can be located anywhere within the grid and orientated in any direction through a series of displacement rotation coordinate transforms. The stars are then plotted on a polar coordinate system centred on the view direction. Two maps are created with a displacement corresponding to the eye separation appropriately scaled. Distances have a logarithmic compression otherwise they could not be perceived well. The non stereo version of this has spectral colours of the stars. In the talk I can fly above and through the Milky Way.

The Galaxy database was treated in the same way and is a combination of the Northern red shift catalogue and southern red shift catalogue. In this case, each dot is a complete Galaxy of up to 100,000 million stars. Red shift data was used to get distance. Chains and ribbons of galaxies across the universe can be seen. Some of the frames of the views from the earth of 30° field of views into the universe, with all Milky Way stars absent. In the talk it is possible to move from Galaxy to Galaxy round the known universe and create Cartesian coordinate maps as well.

Using the star database I have created an interstellar journey from the Sun to Eta Canis Major 2500 light years away where we accelerate up one light year squared for half the journey and decelerate for the rest, taking 16 years to do so. The return journey is similar. The frames show front view in the top half and reverse view in the lower half, at various stages in the journey. Relativistic effects include stellar aberration which tends to bring all the stars towards the front increasingly concentrated as the speed increases, and also spectral Doppler shifts making the stars of the front only visible from light that was transmitted in the infrared as it is shifted into the blue stars from the back move to the front with reverse spectral shift. At half-time the Doppler shift is so large that the microwave background emitted 300,000 years after the creation of the universe is shifted back into the visible. By the time the traveller gets back the earth has progressed 5032 years into the future of the troubles in 32 years. They always move into the future, never to return in time.

The talk discusses the twin paradox, where anyone left back on the earth doesn't experience any of these changes, which isn't a paradox at all, and is explained by space-time diagrams.

The slide show display stereo images which bring the stars into 3D so find your funny red green specs and try the slide show...