What is the general level of math knowledge on these forums?

Place all non-origami related posts in here; films, food, your life etc.

What is your math background? (Please only mark the highest)

Elementary calculations
10
8%
High School Algebra and/or Geometry
45
37%
Calculus
23
19%
College level math and beyond
41
34%
None
3
2%
 
Total votes: 122

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Razzmatazz
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Re: What is the general level of math knowledge on these for

Post by Razzmatazz »

According to M-theory, space can expand much faster than c. I know that. But that isn't matter. Well I guess you could call it "nothing".
the modern einstein

Re: What is the general level of math knowledge on these for

Post by the modern einstein »

if space could expand faster than light, then we would never be able to see the galaxies in the hubble deep field shot, and most stars would be invisible to us, as the light would never be able to reach us.
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Falcifer
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Re: What is the general level of math knowledge on these for

Post by Falcifer »

the modern einstein wrote:if space could expand faster than light, then we would never be able to see the galaxies in the hubble deep field shot, and most stars would be invisible to us, as the light would never be able to reach us.
The only reason I'm replying to this is because your username is "the modern einstein"...

Space can expand faster than light. And it does. Not everywhere, though. Not all parts of the universe are moving away from each other faster than light.

Also, we're not at the center of the universe (or even our own galaxy), so even if the universe were expanding faster than light, galaxies and stars "close" to us wouldn't necessarily be moving faster than light relative to us, which means we'd still be able to observe them.

But there are very distant parts of the universe which move away from each other faster than the speed of light. And there are parts of the universe which are now expanding FTL, which haven't always been doing so.

And even though space is expanding, the galaxies themselves don't increase in size. Just the distances between them. So, since the stars that we see at night (excluding those observed by other means) are part of our galaxy (the Milky Way), we should always be able to observe them from Earth, regardless of how fast the universe expands.
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Razzmatazz
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Re: What is the general level of math knowledge on these for

Post by Razzmatazz »

the modern einstein wrote:if space could expand faster than light, then we would never be able to see the galaxies in the hubble deep field shot, and most stars would be invisible to us, as the light would never be able to reach us.
Space is considered "nothing" and therefore is not constricted by the laws of matter. It still contains the 7 other dimensions though, I believe. Which is how the BBT is suppsoed to play out. Assuming the universe is flat and such. But I don't believe in BBT :P
the modern einstein

Re: What is the general level of math knowledge on these for

Post by the modern einstein »

OK lets have a little diagram > < these two arrows represent light coming towards the end of this line, and space, expanding away from it. Space is like a balloon, and the distance between the light and the end of the line is expanding constantly. If the expansion is faster than the light coming towards the end of the line, then the space between the end of the line and the light will be expanding constantly, proving, that if this were true, then we would not be able to see quite a few galaxies in the universe. if this were the case, then there would be huge gaps between each of the galaxies we can see, due to the expansion of space hiding ones from us. This is not the case - there are no such gaps in what part of the universe is visible, using all technology known to mankind. On the contrary, the universe expands at a constant rate - read "Bang", the complete history of the universe for confirmation. this rate is slower than what light travels at, and there are no spaces where the universe expands faster. If you read more of the book mentioned, it says positively, that due to research on star magnitude, space is expanding at a constant rate throughout, and that rate is increasing, at a constant rate.
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Falcifer
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Re: What is the general level of math knowledge on these for

Post by Falcifer »

the modern einstein wrote:space is expanding at a constant rate throughout, and that rate is increasing, at a constant rate
This year's Nobel prize in physics is going to a team for "the discovery of the accelerating expansion of the Universe through observations of distant supernovae", so I don't dispute the claim that the rate is increasing. (The discovery was made in the mid-90s, though).

However, there seems to be some confusion elsewhere.

It should be made clear that nothing is actually travelling faster than the speed of light. But when it comes to the expansion of space, the laws of physics are not the same.

You also have to remember that the universe isn't really expanding like a balloon. That would imply that the universe is expanding into a space outside itself (like the way a balloon fills the space outside itself when you blow it up).
Instead, the space between galaxies is stretching.

I would suggest reading a few things;
"Distance" in the universe
Is the universe expanding faster than the speed of light?
Travelling faster than light

I'm sure they will help more than I would trying to explain.

It might be worth noting, though, that the Hubble constant is in units of (km/s)/Mpc, which means that for every million parsecs that you move away from Earth, the rate of expansion of space increases by about 70 km/s. Which means that space is not expanding at a constant rate throughout the universe.

Things are complicated further due to the fact that the Hubble constant isn't constant...

the modern einstein wrote:If the expansion is faster than the light coming towards the end of the line, then the space between the end of the line and the light will be expanding constantly, proving, that if this were true, then we would not be able to see quite a few galaxies in the universe. if this were the case, then there would be huge gaps between each of the galaxies we can see, due to the expansion of space hiding ones from us.
Actually, there's no reason why there would be huge gaps between observable galaxies.

There are, obviously, gaps between galaxies, due to the distance between them, but deep field images show that even the "empty" regions of space are filled with thousands of galaxies. Presumably, the gaps between those galaxies also contain similar images, which we don't yet have the technology to observe.

In any case, given that the universe is expanding at a rate of roughly 0.007% every million years, and that the light we see now is from galaxies millions (and sometimes billions) of years ago, there's not much of a distance to be seen. Not significant, anyway.

At this very moment, there may indeed be (and probably are) much larger distances between galaxies. But because we only have the (very old) light to tell us where things are, the gaps won't appear for millions/billions more years to come.

In fact, because the rate of expansion increases as the distance increases, over billions of years, galaxies will begin disappearing altogether (they won't actually cease to exist, but we won't be able to see them anymore), creating even larger gaps.

I don't see any reason why the expansion of space would "hide" galaxies. Beyond a certain distance, the universe won't be observable, that's true. But everything else that has yet to pass that "horizon" could still be observed. And even galaxies which have now passed it may have, at one time, emitted light which will reach Earth.
It doesn't stop us from being able to see other galaxies which are closer, though.
the modern einstein

Re: What is the general level of math knowledge on these for

Post by the modern einstein »

What you have quoted is my theory IF space expanded faster than light, and it doesn't. this I know not to be true. You are just reiterating books I have already read - most of what you say is all good, and I already knew it, but some of it - you've misunderstood my meaning. The balloon is just a visual model - to help understand things better, as well as that, I know we can see most of the universe, and there are no huge gaps, but there would be if space expanded faster than light. http://www.bing.com/images/search?q=red ... ORM=IDFRIR might be a good image to help, even if it's about redshift. I'm saying that IF space expanded faster than light, then the space between the sun/galaxy, and human would be increasing constantly, faster than the light could travel, and the human would never see it.
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Falcifer
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Re: What is the general level of math knowledge on these for

Post by Falcifer »

the modern einstein wrote:What you have quoted is my theory IF space expanded faster than light, and it doesn't. this I know not to be true.
Can I ask how you know it's not true? And how you came to the conclusion?
the modern einstein wrote:some of it - you've misunderstood my meaning
I'd like to know where, and also for you to clarify, because I've been reading up on the subject and I thought I had a good grasp of the basics.
In any case, it fascinates me, so I would like to know where I'm misunderstanding.
the modern einstein wrote:there are no huge gaps, but there would be if space expanded faster than light
Again, space expanding faster than light only applies at extreme distances.

As I understand it, the gaps that you're talking about won't appear to us for billions of years, when the light from the (now) very distant galaxies reaches us, and the light from the even more distant galaxies is unable to do so.

What we see now is a snapshot from billions of years ago, before the galaxies moved significantly apart.

With subjects that are relatively new to me, I tend to do a lot of searching for articles and information, which is why I'm so adamant about this. For me, I understand it well enough to know that space can (and does) expand faster than light.
Nothing that you've said has led me to believe otherwise. And I've linked where I got most of my information, which you tell me is correct, but you still insist on saying that you know for a fact that space can't expand faster than light. So I'm confused about where the misunderstanding is.

As I said, though, I'm confident enough about my own interpretation of what I've read, so I'm going to give up trying to explain.

If you can link me to anything, or if there are any books on the subject that you'd recommend, I'd appreciate that.
the modern einstein wrote:I'm saying that IF space expanded faster than light, then the space between the sun/galaxy, and human would be increasing constantly, faster than the light could travel, and the human would never see it.
I'll leave you with this article which shows "that we can observe galaxies that have, and always have had, recession velocities greater than the speed of light."
the modern einstein

Re: What is the general level of math knowledge on these for

Post by the modern einstein »

Ok; I just had little read up on some other websites that i trust - they confirm what you say - but they still say that the light that is leaving the galaxies right now will never reach us, exactly what i was saying, the websites you posted up are saying, the websites I had a look at are saying, etc, etc. I was half right at least. I have a fairly old fashioned view of physics, because I use books instead of the internet, and they were all reiterating what I was arguing for - but they are not as up to date as most websites. :cry:
likeaboss
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Re: What is the general level of math knowledge on these for

Post by likeaboss »

Light will reach us eventually from other galaxies
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Axel´s Origami
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Re: What is the general level of math knowledge on these for

Post by Axel´s Origami »

But some galaxies ar so far away that when the light gets here the sun will have swallowed the earth and we'll be dead. so we'll never see them.
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Re: What is the general level of math knowledge on these for

Post by phillipcurl »

Theoretically, the creation of new galaxies and even universes, possibly, is always going on. therefore, there is a ever increasing number of galaxies so the light from some at the farthest reaches of this universe would never reach earth, if you think about it the way you guys are. but, if you think about the universe as a soccer ball, all light would exit one side and enter in through the "mirror" of it on the other side. Lets think that our galaxy is near the edge of the "soccer ball" . light from one side of the universe could reach our planet within a few years. this would, though, make it look like the other galaxy could be closer than it actually is to ours.

but, who knows if this is actually the case. hell, i don't even know if what i'm saying makes sense.
thats my somewhat stupid theory.
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