The Big Bang Theory Wrong?

Originally posted by sonhouse
That raisin idea is pretty close to reality. For a long time I thought the expansion included all the atoms of the universe getting larger at the same time but then found out the only thing expanding is the distance between galaxies. Not sure yet why that doesn't include every atom, you would think the space bits inside each atom would get less dense as tim ...[text shortened]... must be something else going on that prevents that.

Have no idea what that would be however.

There is a lot of work ahead for the cosmologists. I hope there will be a practical use for the knowledge as things unfold.

Originally posted by joe beyser
It just appears that way. Not just here but from everywhere. You have said that space is expanding. I agree with that for now.

Maybe space expanded in the past and that is what scientist see. Perhaps space is no longer expanding.

The Instructor

Originally posted by joe beyser
I do not need a reference as I can see distant stars and the fact they are visible tells me that we are not expanding at light speed or even half light speed.

So anything moving at half-light speed is invisible?
Amazing.
I did not know that... where can I find out more?

Originally posted by joe beyser
It just appears that way.

And I asked in what way it appears that way. Is it just in the sense that if you fall in the ocean where you can't see land, you feel like you are in the middle of the ocean? If so, it seems a rather trivial observation and not 'fascinating' as you earlier said. Or is there more too it?

Originally posted by RJHinds
Maybe space expanded in the past and that is what scientist see. Perhaps space is no longer expanding.

The Instructor

The latest is not only is the universe expanding but starting about 5 billion years ago it started into a new regime where it started expanding even faster. That is one of the ongoing mysteries of the universe right now, the reason for that sped up expansion.

Originally posted by sonhouse
The latest is not only is the universe expanding but starting about 5 billion years ago it started into a new regime where it started expanding even faster. That is one of the ongoing mysteries of the universe right now, the reason for that sped up expansion.

But they claim they are just now seeing things that were happening millions and billions of years ago depending on how many light years away what they are viewing is. If that is so, then how can they know how fast it is expanding today or even if it is still expanding? It may have long ago stopped expanding.

The Instructor

Originally posted by RJHinds
But they claim they are just now seeing things that were happening millions and billions of years ago depending on how many light years away what they are viewing is. If that is so, then how can they know how fast it is expanding today or even if it is still expanding? It may have long ago stopped expanding.

The Instructor

They measure the expansion with what are called 'standard candles'. It was found a few decades ago there is a kind of supernova explosion that happens to give off about the same energy whether it is one in our galaxy or one in a galaxy a billion light years away.

So using that discovery, they can tell how far away things are (among other techniques which also converge on a common date) by just measuring how strong the light from such a standard candle is.

Because light from a star or nova or supernova expands in all directions pretty much the same, just using the inverse square law allows a measure of the distance to a supernova and that in turn tells the distance to the galaxy which it is embedded which is what they really want, the distance to galaxies.

So with that in mind they started measuring the standard candles and found the measured intensities didn't add up right and what fit the new pattern found was 6 billion years ago the universal expansion actually started speeding up.

Of course it is normal to take such measurements with a grain of salt, all scientists do that but so far the expansion hypothesis fits the facts.

Like Humy says, the first indication of the expansion of the universe was doppler shift which if you don't know what that is, google it. Next time you get a ticket for speeding you can thank doppler shift for measuring YOUR personal expansion into space along the highway.

Originally posted by RJHinds
But they claim they are just now seeing things that were happening millions and billions of years ago depending on how many light years away what they are viewing is. If that is so, then how can they know how fast it is expanding today or even if it is still expanding? It may have long ago stopped expanding.

The Instructor

how can they know how fast it is expanding today or even if it is still expanding?

isn't it obvious how? SURELY, even you must have heard of the Doppler shift!? This is very common knowledge:

http://en.wikipedia.org/wiki/Doppler_effect

all the furthest and most distant galaxies are observed to be moving away from us via the Doppler shift so there is absolutely no doubt that the universe is expanding.

The Doppler effect has also been measured in the lab using moving lasers and has been confirmed to be a real effect that can be used to accurately measure relative speed exactly as relativity predicts. Doppler radar relies on it and much of our technology wouldn't work without it!:

http://en.wikipedia.org/wiki/Doppler_radar

If the Doppler shift does not reliably and accurately measure relative speed, Doppler radar wouldn't work! And yet Doppler radar does work.

The standard candles sonhouse has just mentioned greatly increase both the reliability and accuracy of our estimates of the speed of the expansion of the universe.

Originally posted by humy

how can they know how fast it is expanding today or even if it is still expanding?

isn't it obvious how? SURELY, even you must have heard of the Doppler shift!? This is very common knowledge:

http://en.wikipedia.org/wiki/Doppler_effect

all the furthest and most distant galaxies are observed to be moving away from us via the Dopple ...[text shortened]... accurately measure relative speed, Doppler radar wouldn't work! And yet Doppler radar does work.

Of course, I know that. However, they can't be sure any expansion of space is still happening. They can only determined that it happened sometime in the past. They can not even be sure when it happened, even though they believe it was so and so years ago.

The Instructor

Originally posted by RJHinds
Of course, I know that. However, they can't be sure any expansion of space is still happening. They can only determined that it happened sometime in the past. They can not even be sure when it happened, even though they believe it was so and so years ago.

The Instructor

All that noise from you about 'they can't know this, they can't know that' is just that: NOISE from you.

You have no scientific credibility to say one way or the other whether scientists can 'know' something.

All you can do is bleat one more time about how GODIDIT and how evil science is.

Imagine the nerve, scientists actually using the intelligence, actually a LOT more intelligent than either you OR me, using the intelligence supposedly given to us by your god to come up with solid scientific conclusions.
That must tick you off no end.

Originally posted by RJHinds
Of course, I know that. However, they can't be sure any expansion of space is still happening. They can only determined that it happened sometime in the past. They can not even be sure when it happened, even though they believe it was so and so years ago.

The Instructor

they can't be sure any expansion of space is still happening. They can only determined that it happened sometime in the past.

NO, they CAN be rationally sure it is expanding now. There reason being is because of the known laws of physics which have been repeatedly confirmed to be correct both experimentally and by just observations.

Physics (actually, more like basic logic to be more precise ) tells us the expansion of space must continue to happen unless something causes it to stop expanding. There is nothing known that could have conceivably stopped such an expansion of this gigantic magnitude so the default assumption must be it is continuing and it would be idiotic to assume otherwise because, to assume otherwise would be analogous to assume that it is credible that the Earth is no longer spinning on its axis in the present second as opposed to the last second -you can adapt the same kind of flawed reasoning you are using here above to “they can't be sure any rotation of the Earth is still happening. They can only determined that it happened sometime in the past (the last few seconds ). “. I hope you can now see the flaw in your reasoning: -in both cases, you must explain WHAT could have credibly and conceivably CAUSED it to stop doing what it did in the past! -else you have no argument.

Originally posted by humy

they can't be sure any expansion of space is still happening. They can only determined that it happened sometime in the past.

NO, they CAN be rationally sure it is expanding now. There reason being is because of the known laws of physics which have been repeatedly confirmed to be correct both experimentally and by just observations. Physi ...[text shortened]... ning. They can only determined that it happened sometime in the past (the last few seconds ). “.

Well flawed reasoning and logic is RJ's modus operandi.

Originally posted by humy

they can't be sure any expansion of space is still happening. They can only determined that it happened sometime in the past.

NO, they CAN be rationally sure it is expanding now. There reason being is because of the known laws of physics which have been repeatedly confirmed to be correct both experimentally and by just observations.

P ...[text shortened]... bly and conceivably CAUSED it to stop doing what it did in the past! -else you have no argument.

The scientist are the ones that should be making explanations that are credible. How can they be credible when they assume this and assume that. You know what happens when we ASSUME don't you? It just makes an ASS out of U and ME.

The Instructor

Originally posted by RJHinds
The scientist are the ones that should be making explanations that are credible. How can they be credible when they assume this and assume that. You know what happens when we ASSUME don't you? It just makes an ASS out of U and ME.

The Instructor

Mostly you. The fact you refuse to accept most anything in science is just the result of your inability to think for yourself, instead letting other people do your thinking for you.

You gave up the ability to reason for yourself decades ago.

Originally posted by sonhouse
Mostly you. The fact you refuse to accept most anything in science is just the result of your inability to think for yourself, instead letting other people do your thinking for you.

You gave up the ability to reason for yourself decades ago.

U are the 1 that ASSUME what the scientist ASSUME is true, when it could very well be false. I am smart enough to accept what the scientist PROVE, but not what they ASSUME.

The Instructor