What is the Universe expanding into..

Do you think there was anything before the big bang?

  • I don't think there was anything before the Big Bang

    Votes: 56 12.5%
  • I think something existed before the Big Bang

    Votes: 200 44.7%
  • I don't think the big bang happened

    Votes: 54 12.1%
  • I think the universe is part of a mutiverse

    Votes: 201 45.0%

  • Total voters
    447
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Many are the Mysteries of the Universe. I can scarcely keep up with them all, except by bringing Clarity to the individual matters.

Even the Kepler problem of Planets under the inverse square Law is little understood, which is why I try to find time for Lectures about the central inverse-square force:

https://johncarlosbaez.wordpress.com/2015/03/17/planets_in_the_4th_dimension/

What is boils down to is that Energy and Angular Momentum is Conserved. But a Third more abstract Quantity is also Conserved, and we don't often think about this:

https://en.wikipedia.org/wiki/Laplace–Runge–Lenz_vector

This, in a nutshell, is the Eccentricity of the Orbit. And it relates to a symmetry of Time itself, IMO. Amazing!
 
Time on iss and on earth are ticking differently . Just sayin .

There's two effects.

First is Velocity, which is Special Relativity so the guy on Earth ages faster:
For example, when astronaut Scott Kelly spent nearly a year aboard the International Space Station starting in 2015, he was moving much faster than his twin brother, astronaut Mark Kelly, who spent the year on the planet's surface. Due to time dilation, Mark Kelly aged just a little faster than Scott — "five milliseconds," according to the earth-bound twin. Since Scott wasn't moving near lightspeed, the actual difference in aging due to time dilation was negligible. In fact, considering how much stress and radiation the airborne twin experienced aboard the ISS, some would argue Scott Kelly increased his rate of aging.

Second is Gravity, which is General Relativity and the guy on Earth ages slower:

With additional effects from general relativity (Einstein's follow-up to special relativity that incorporates gravity), clocks closer to the center of a large gravitational mass like Earth tick more slowly than those farther away. That effect adds microseconds to each day on a GPS atomic clock, so in the end engineers subtract 7 microseconds and add 45 more back on. GPS clocks don't tick over to the next day until they have run a total of 38 microseconds longer than comparable clocks on Earth.

https://www.space.com/36273-theory-special-relativity.html

Quite tricky to calculate, IMO. These effects work in opposite directions, don't they?
 
system7 said: I have learned something most interesting from Planck Units. Energy is proportional to the inverse of Distance.
I'm drawing a blank here. From where did you learn this?

That's a dimensional problem. Energy = A/r in terms of potential Energy. Familiar equation, The Hamiltonian of central forces. It's in the Woit book.

https://johncarlosbaez.wordpress.com/2015/03/17/planets_in_the_4th_dimension/

Now this is interesting:

What’s this fourth dimension I’m talking about here? It’s a lot like time. But it’s not exactly time. It’s the difference between ordinary time and another sort of time, which flows at a rate inversely proportional to the distance between the planet and the sun.

What else is inversely proportional to distance in the Kepler problem?
 
There's two effects.

First is Velocity, which is Special Relativity so the guy on Earth ages faster:


Second is Gravity, which is General Relativity and the guy on Earth ages slower:



https://www.space.com/36273-theory-special-relativity.html

Quite tricky to calculate, IMO. These effects work in opposite directions, don't they?
These TWO effects are taken care of satellites of the GPS system.
If they were not, positioning should not work at all because of two much clock drift. A nano second is a foot long.
 
Thanks, Morison's blog will be of interest to all earth-bound amateur astronomers.

Suffering just slightly from the problem myself, I read his blog on "Cataracts - an astronomer's story", and rather wish I hadn't!

Here's an extract from his book:
Aa, so Cosmos is the "biggest" entity we talk about. So thats everything?

Cosmos -> Universe -> Visible universe -> ... OK?

//
 
Part of the extract reads "different universes within the overall cosmos".

The definition of "cosmos" is "the universe, especially when it is understood as an ordered system".

So, perhaps Morison considers that the cosmos is an ordered system of universes? 🤔
 
Familiar equation, The Hamiltonian of central forces.

Define "familiar"! 😀

The Hamiltonian is associated with orbits in central force fields.

I read that the Hamiltonian description is especially useful for finding conserved quantities, which play an important role in describing orbits.

I also read that Hamiltonian mechanics is a reformulation of Lagrangian mechanics.

However, it's all Greek to me! 😵 https://en.wikipedia.org/wiki/Hamiltonian_mechanics
 
I had to duck out last night. Decided I would learn more about the Universe from a good Physics book than listen to the random remarks here.

Shame on you! Lazy students!

Aside all the interesting considerations of Gravity, Relativity and Quantum Mechanics, you need a reset in your thinking.

Only 5% of the Universe is Particles. Mainly Protons by mass. Photons and electrons are a tiny fraction of that, but are what we mostly see in our lives. The Electromagnetic force is 99%.

20% may or may not be Dark Matter. Maybe massive right-handed Neutrinos. Nobody knows. If Dark Matter disappeared tomorrow, we wouldn't notice for millions of years, so slowly does our galaxy rotate.

75% is Dark Energy, which may or may not be the Energy of Space-Time itself.

What it boils down to, is it is Fields that make up the Universe. Particles are just a sugar-dusting on the main event. Excitations of the Field.
 
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