You are still comparing the expansion of the universe to an ordinary explosion, which involves outwards expansion.
Instead, the expansion of the universe occurs everywhere at once. The universe has no outwards expansion, and consequently there's no need to contemplate an 'outside'.
When we talk of the expansion of the universe, we really mean the expansion of four-dimensional spacetime.
The way distance is measured in spacetime (the metric) is different from the way distance is measured on the surface of the Earth. This makes spacetime distance difficult to perceive. Points in spacetime are specified by four coordinates, one of which is cosmological time. The geometry of spacetime is weird in that the distance between points with constant coordinates increases with time rather than remaining constant. 😵
Spacetime metrics is a lot of fun - not! 😉
http://burro.cwru.edu/Academics/Astr328/Notes/Metrics/metrics.html
The notion is that universe started as the size of a golf ball - right?
And now it is bigger. Can one get from A to B in no(=0) time?
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And now it is bigger. Can one get from A to B in no(=0) time?
//
It's expanding into whatever was there before the big bang.
And people doubt the existence of God, hhmmmm
And people doubt the existence of God, hhmmmm
TNT - I'm not sure if I am interpreting your 'zero time' question correctly, but here goes:
The metric changes with time in a way that causes distances to appear larger at later times.
The theory of cosmic inflation says that, during the first 10^-32 s after the Big Bang, the metric grew exponentially, causing space to change from smaller than an atom to around 100 million light years across.
If you have questions about cosmic inflation, best ask Ethan!
https://bigthink.com/starts-with-a-bang/why-big-bang-happened/
The metric changes with time in a way that causes distances to appear larger at later times.
The theory of cosmic inflation says that, during the first 10^-32 s after the Big Bang, the metric grew exponentially, causing space to change from smaller than an atom to around 100 million light years across.
If you have questions about cosmic inflation, best ask Ethan!
https://bigthink.com/starts-with-a-bang/why-big-bang-happened/
In general, a metric relates physical distances between objects separated in space to the coordinates used to describe their position.
The most general form of four-dimensional spacetime metric is the Robertson-Walker metric, which describes a curved space which is either expanding or contracting. This model is sometimes called the Standard Model of modern cosmology.
https://en.wikipedia.org/wiki/Friedmann–Lemaître–Robertson–Walker_metric
I'm no bright enough to understand all the mathematics, I can only try to extract some meaning! 🙁
The most general form of four-dimensional spacetime metric is the Robertson-Walker metric, which describes a curved space which is either expanding or contracting. This model is sometimes called the Standard Model of modern cosmology.
https://en.wikipedia.org/wiki/Friedmann–Lemaître–Robertson–Walker_metric
I'm no bright enough to understand all the mathematics, I can only try to extract some meaning! 🙁
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So have I! 😀
The idea that objects can have constant spatial coordinates while the distance between them increases with time certainly makes my mind boggle!
From my earlier link: "Imagine a distant galaxy. It is located at the coordinate (r, theta, phi). As long as no force acts on it it will always be at that coordinate."
However, its proper distance does change in line with the Robertson-Walker scale factor:
https://en.wikipedia.org/wiki/Scale_factor_(cosmology)
I give in! 😀
The idea that objects can have constant spatial coordinates while the distance between them increases with time certainly makes my mind boggle!
From my earlier link: "Imagine a distant galaxy. It is located at the coordinate (r, theta, phi). As long as no force acts on it it will always be at that coordinate."
However, its proper distance does change in line with the Robertson-Walker scale factor:
https://en.wikipedia.org/wiki/Scale_factor_(cosmology)
I give in! 😀
In future we are going to make some thing out of nothing . I also believe we have done what we can science . Now its beyond human understanding . Now its turn for ultra intelligent ai machine to take over . They can travel larger distances .can reproduce without pain .evolve very quickly . Long life . Can withstand harsh weather . And most important can live in space .
No current theory mathematical or physical can be trusted here.
What we are sure is that it's expending into a very large diameter fullrange driver with an exceptional BL to mass ratio.
What we are sure is that it's expending into a very large diameter fullrange driver with an exceptional BL to mass ratio.
All data is rendered by computers . We are just link between them and the expanding universe .
I think humans deserve greater credit than simply being intermediates!
Humans managed to observe and measure the expansion of the universe in the 1920s when human computers still did the sorts of calculations nowadays carried out by electronic computers.
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