Speed of light and expansion of space

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How would an accelerating universe rule out a closed one? My astronomy textbook specifically states that the universe's expansion is accelerating *and* that we still don't know whether it's open, closed, or flat.


How accurate are these measurements? It would seem very difficult to measure the curvature of the universe from within a gravity well.

gravitational lensings gives us some idea of curvature in places where it can be observed.

ruveyn

I don't know the answer.

If the universe started with a big bang then it should look like one of those big fireworks. An expanding sphere of glowing bits and empty in the center.

But I think we don't know squat for all our jet planes and computers.

We don't really know what magnetism is or time or gravity or anything else.

So light is "both a particle and a wave". Really? What does that mean?

If light is a particle then why can it go through six feet of glass but be stopped by a sheet of carbon paper?

If one photon is given a choice of going through several slits in a grid then how can it manage to go through ALL of them.

Or perhaps none of them. What about poor Schrodinger's cat?

If you look at photons while in flight in space you see waves. If you detect them at a locality, you see particles. It depends on what kind of measurement or observation you are making. If you look at a cylindrical can straight down you see a circle. If you look from the side you see a rectangle. It depends how you look at the object.

ruveyn

You are thinking three dimensionally The universe is possibly a four dimensional sphere whose radius is the dimension of time.

You are thinking three dimensionally The universe is possibly a four dimensional sphere whose radius is the dimension of time.[/quote

It could be 10 or 11 dimensional too. it depends on what fancy theory you adhere to.

ruveyn

Nope. The universe doesn't have a center that it 'exploded from'. The universe is the 'explosion'.



It can do it because it is both a particle and a wave.

That sounds very interesting until you stop to think about it and then you realize it means nothing except "we don't know".

I am an electrical engineer. I learned about "magnetic lines of force" which you could see with a magnet and some iron filings.

I asked the teacher "What IS a magnetic line of force. What actually is in that space? If you had a huge electron microscope could you actually SEE anything there"?

He didn't know. I don't know. No one knows.

They say nothing can happen without an expenditure of energy. To move anything requires energy.

But if you have a magnet and slide it towards another magnet on a table then it will either attract or repel it.
Where does the energy come from?

If the mass of the Sun "attracts" the earth, or the Earth attracts the Moon what energy is is being used?

We don't know.

But we do know. Quantum Electrodynamics gives predictions that are correct to 12 decimal places and Quantum Electrodynamics has not yet been empirically falsified. That is is close to "knowing" as we can get or need to get.

ruveyn

[quote="ruveyn"
But we do know. Quantum Electrodynamics gives predictions that are correct to 12 decimal places and Quantum Electrodynamics has not yet been empirically falsified. That is is close to "knowing" as we can get or need to get.
ruveyn[/quote]

Ahh, but Quantum theory is a theory as is Relativity, String theory and others.

Some say there was a Big Bang, some say there wasn't. Some say there is "black matter" and some say there isn't.

If and when we really understand the basics of the universe then we might live in the Star Trek universe of antigravity, and faster than light travel.

For the moment we still don't know what magnetism is.

i am thinking about a "possibility" matrix.

the fact that there are manifestations that are located in a position, means that possibilities are increased for other manifestations to also be located in that position.

the possibilities for locations of manifestations in a "position" are exponentially increased as they get closer to the position of an actual manifestation that they are situated near by.

therefore a "gravitation" toward a greater possibility of location is a function of the fact that an established manifestation is existent in a locus in the direction of the radial exponent of increasing probability of an actual manifestation.

i am too tired to talk about it now and i should not hit "submit" but i did.

Science is theory corroberated by fact (experimental observation and measurement). That is how we know what the world is like. It does not get any better than that. "Truth" is for the philosophers and mathematicians. Experimentally corroberated theories is what scientists have.

ruveyn

There is no such thing as absolute truth because proof in science is not like proof in mathematics. All that can be done is corroborate theories with experimental observations and confirmation of predictions. In that way we can get approximate truths but not absolute truths because we can never know if a theory will be falsified or at least have to modified in some way due to a future experimental observation. But approximate truths are all that's needed.

My point, exactly.

ruveyn

Infinite infinity topic

When I imagine all this universal expansion I envision something unable to be described using words--the abstraction is exceedingly complex.

this does not render the expansion unintelligible, though it is certainly indescribable at our currnet level of communication. But \i also suspect that the description is always a step beyond, and just out of reach, thus ensuring our imaginations to be just under the speed of light. Exciting, and a challenge to strive for.