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Narrowband

we can make things go faster tan light i think


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I think the current thinking is that the total energy of the universe is zero and the positive stuff we see is balanced by negative energy that we are just beginning to understand.

Simples, Ying and Yang - I'll go along with that, have always thought there had to be some kind of balance somehow, and that throws up other questions!!

That would mean your question would have no answer. Now, we usually don't like that!

:icon_salut: Now we can have that, can we?

We know so much, but understand so little!

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I think the current thinking is that the total energy of the universe is zero and the positive stuff we see is balanced by negative energy that we are just beginning to understand.

Also remember that gravitational potential energy is negative, and so the creation of matter can be compensating by increasing the amount of (negative) gravitational potential there is. As Alan Guth said, the Universe is the ultimate free lunch!

But it's also important to realize that conservation of energy is a consequence of time symmetry. At a moment of creation, if there is such a thing, you don't have time symmetry and so you don't have to conserve energy.

That's a very interesting point. I never thought of that before. There appears to be at least one point in time where time symmetry doesn't hold (the BB), and so it's not certain that energy conservation has to hold there either. Fascinating.....

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Also remember that gravitational potential energy is negative,

I dimly remember from my academic days that there is a real problem trying to make sense of gravitational energy as something that can be "localised", that is, point to it and say "there it is, there is so much of it". It's quite a slippery concept. Maybe people understand it better these days.

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I dimly remember from my academic days that there is a real problem trying to make sense of gravitational energy as something that can be "localised", that is, point to it and say "there it is, there is so much of it". It's quite a slippery concept. Maybe people understand it better these days.

Perhaps, but even if it isn't localised, wouldn't it still be possible to integrate it over the volume of the Universe (whatever that means!), and demonstrate that it allows all forms of energy to sum to zero?

(When I say "possible" I don't mean "practical" :icon_salut: )

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A good way of squaring the idea of the observable universe being bigger than it should be based on the evidence is to do a thought experiment.

take a deflated balloon. Draw 2 dots on it 10cm apart.

In this universe, light travels at 1cm\minute. So for light to go from one dot to the other would take 10 minutes.

Now blow up the balloon. How far apart are the dots now? for the sake of argument, call it 40cm. Now light still travels at 1cm\minute. So now it's going to take 40 minutes for light to go from dot A to dot B.

this inflation is essentially what the universe is doing. So while light travels at a set speed, the spacetime it's travelling through is inflating. Which is how the observable universe can be much bigger than it should be given the age of the CMBR.

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