It’s complicated and cosmologists are not certain. One of the issues is only being able to see about 4% of the mass in the universe – the stars, planets, gas and dust. About 25% of the mass of the universe is Dark Matter. It’s “dark” because it doesn’t emit light that enables us to see ... Read more how will the Universe end?
You might remember that we looked at some paradoxes when we studied special relativity earlier this term. Here is another situation where a paradox can arise. The German astronomer Heinrich Olbers (1758–1840) asked why the night sky was dark. At the time, astronomers believed that the Universe was both infinite and steady state (unchanging), so ... Read more evidence in support of the big bang: #3 olbers’ paradox
As we worked through the diagram explaining the stages of the Big Bang model, we looked at a section of the diagram where the Universe was hot enough for nuclear fusion. At this point, hydrogen nuclei were fusing together with other hydrogen nuclei to create helium nuclei. As the Universe expanded, it cooled and further ... Read more evidence in support of the big bang: #2 nucleosynthesis
introduction to the Big Bang from mr mackenzie on Vimeo. Georges Lemaître’s theory of an expanding Universe, which has become known as the Big Bang, was supported by Hubble’s observations. The expanding Universe idea was challenged by influential scientists who believed the Universe was both infinite (and therefore not expanding) and steady state (unchanging). Supporters ... Read more evidence in support of the big bang: #1 CMBR
In the 1920s, Edwin Hubble had access to the Hooker telescope on Mount Wilson, Los Angeles. This was the largest telescope in the world at that time. His first breakthrough was the discovery of a cepheid variable star in the Andromeda nebula. This enabled him to calculate the distance to Andromeda and he quickly realised this was ... Read more the Milky Way is not alone
For the past two weeks, we’ve been looking at equations that describe time and distance changing according to speed. It’s been quite heavy on theory and maths with no supporting evidence to suggest Einstein’s ideas were correct. I want to address that lack of evidence by pointing you to some practical work that had been ... Read more evidence that special relativity is real
Here is a link to some revision notes for the Our Dynamic Universe unit.
We’ve been looking at Einstein’s special theory of relativity this week. Special relativity is tricky get get your head round. Let’s start with a video about the speed of light. We watched this video in class, it follows Einstein’s thought process as he worked through his special theory of relativity. special relativity from mr mackenzie on ... Read more
I’ve marked your HW jotters and will hand them back during tomorrow’s lesson. I’ll go over the main issues in class but many of you need to review the way you attempt tension questions; use a free body diagram and only use F=ma when you know the resultant force. These two videos should help. HW ... Read more
Your homework questions are attached. Please return to me by Wednesday 20th September.