caharris

That's what I get for only being halfway done with his book, eh?

I might be able to answer this, actually. (And if not, I have Guth's book, so I could look it up upon further inquiry.) The universe would have started in a false vacuum in the Higgs field, which is where it got the negative pressure, and thus repulsive gravity. After a certain point, though, the Higgs field would have changed values (to the current energy density, that of the vacuum), and so inflation wouldn't occur again. Of course, I could have just explained that terribly, so who knows if that makes any sense to you.

Yes I think it was a glitch. I was unaware that two threads were created, sorry for the inconvenience. As for everyone else, thank you for the explanations, and I will let you know how any further explanation goes.

Well I think the way that he is picturing the universe is like we were inside of a sphere or something. He thinks that because the universe may be finite, that this means the universe has a center, or middle, like a sphere has a radius. I don't know how much it will help to use the balloon analogy, because he thinks the expansion of the universe is irrelevant to whether there's a center, sort of like if you lengthen the radius of a sphere there is still a center.

I consider myself to be fairly up-to-date when it comes to astronomy and cosmology, given that I've never taken an official class on either subjects. I read the popular science books, and I have a few text books about it. So the basic concepts of how the universe works are things that I decently understand. I was having a conversation with a person the other day about the center of the universe. I tried to explain how the universe is isotropic and homogeneous, and how we observe space expanding, and how this suggests that there is no center or middle of the universe. However, he insisted that the expansion of the universe and how the things inside it have nothing to do with whether there is a center of the universe or not. He said that when he means center, he is not talking about a source or origin, but 'middle.' I've used the balloon analogy, I've used FAQs from Sean Carroll and Ned Wright, I used part of a lecture from Lawrence Krauss... Yet, either something isn't clicking with this guy, or I just completely misunderstand the question. So I thought I'd ask you guys (and gals). I'm thinking the reason he might not understand is he is thinking of the universe as if it were some shape and we just live inside of it (e.g. fish living in water). So the question is, What does it mean when physicists say there is no center of the universe? Thank you for your time, caharris

I consider myself to be fairly up-to-date when it comes to astronomy and cosmology, given that I've never taken an official class on either subjects. I read the popular science books, and I have a few text books about it. So the basic concepts of how the universe works are things that I decently understand. I was having a conversation with a person the other day about the center of the universe. I tried to explain how the universe is isotropic and homogeneous, and how we observe space expanding, and how this suggests that there is no center or middle of the universe. However, he insisted that the expansion of the universe and how the things inside it have nothing to do with whether there is a center of the universe or not. He said that when he means center, he is not talking about a source or origin, but 'middle.' I've used the balloon analogy, I've used FAQs from Sean Carroll and Ned Wright, I used part of a lecture from Lawrence Krauss... Yet, either something isn't clicking with this guy, or I just completely misunderstand the question. So I thought I'd ask you guys (and gals). I'm thinking the reason he might not understand is he is thinking of the universe as if it were some shape and we just live inside of it (e.g. fish living in water). So the question is, What does it mean when physicists say there is no center of the universe? Thank you for your time, caharris

Sorry, I just never check wiki I figured I would ask here since I can get the formula (reliably) and ask questions about it if I don't get something.

This should be a relatively simple question (pun intended): is there a single formula combining the time dilation from both gravity and velocity? Or is there a series of equations to combine them? (And what is it/are they?)

By the way, does the figure we get, 13.7 billion, take into account the different accelerations?

Thank you for clearing everything up, I do appreciate it. I'm getting ready to start my first year of college this fall (majoring in physics, of course ), so even though your recommended books may be over my head, I can always google it

So it's measured by an object that moves with the expansion of the universe (so it looks like it isn't moving)? Also, what is a good book/website that explains this in a more in-depth/mathematical detail?

No agenda, I still state that the universe is 13.7 billion years old and came from natural causes. I just thought it would be wiser to put it in 'Speculations' since it could lead to speculations (For example, if we get 13.7 billion years old from our sense of time (from our gravity and speed) couldn't we say that the universe is only a second old from another perspective, and still be factually correct?) But if you think it should be moved, by all means, let's get it moved

I've probably misunderstood something, so if you could help me understand I would appreciate it. If time is relative, how can we actually say how old the universe is? It may be 13.7 billion years old for us, but couldn't it be different somewhere else? These are the questions that haunt me

Well, if we can't tell the difference, why not just apply Occam's Razor and say it's just real?

If we can dismiss what atheists say as long as they don't have a grad degree in math or physics, does that mean we can dismiss religious people as long as they don't have a grad degree in math or physics? O'Rielly, and in fact most religious people (that I know, at least) don't have a firm background in math or science, should we henceforth ignore absolutely everything they has to say?

How could we tell the difference between an illusion as reality, and plain ol' reality?

Red pill or blue pill? (Matrix reference. Couldn't help myself.)

Sounds about right, then. Thank you guys for the help! If anything else comes to mind let me know, if you would please. Edit: I looked at the book as a PDF, and it's exactly what I'm looking for. I will most certainly buy it. Thanks again!

I'm in 12th grade, getting ready to go into college to get my major in physics, getting ready to take the placement exams for my classes, and I'm sitting here thinking: Man my school gives really crappy math education. (The physics teacher is awesome, though.) So this is the predicament I find myself in. I really don't want to take college algebra. For me, that's just unacceptable. While I have a really good understanding of algebra, my knowledge in trig suffered tremendously because of the terrible work ethic of my teacher. (We talked about polar coordinates for about three weeks longer than needed.) So I'm looking for a good trig (and algebra, if you don't mind) review book. Nothing too detailed, because I kept all of my notes and understood it the first time. I just need something to keep on my bookshelf for refreshers. But I would also like a good pre-calculus book, and most importantly a self-teaching calculus book. I have "Calculus Made Easy" by Silvanus P. Thompson on my Kindle (math books are terrible on the Kindle, by the way) which is good, and "Calculus for Dummies" which isn't bad. But I'm looking for something rigorous and comprehensive. I looked at the 'Master Math' series of books, but I don't know how good they are. I also thought about "Calculus: An Intuitive and Physical Approach" by Morris Kline to teach myself. Are these books any good, and what books would you recommend? Thank you for you time and help, Chris

Lawrence Krauss wrote it. The Black Hole War by Leonard Susskind On the Shoulders of Giants by Stephen Hawking (just for convenience). The Greatest Show on Earth by Richard Dawkins

The Moral Landscape by Sam Harris Excellently written. Sure his ideas may not be completely original or you may not agree, but he presents his ideas in a very accessible way. The Greatest Show on Earth: The Evidence for Evolution by Richard Dawkins Need I say anything? Perfection. The Blind Watchmaker: Why the Evidence of Evolution Reveals a Universe Without Design by Richard Dawkins Good, but I got bored with it. Why Evolution is True by Jerry Coyne After reading The Greatest Show on Earth, this was a tad redundant. Well written, but don't read these two back-to-back. A History of Western Philosophy by Bertrand Russell Still in the process of reading, but it's a great text about the progression of ideas in western philosophy. The Grand Design by Stephen Hawking and Leonard Mlodinow Meh. It isn't that I disagree with any of it, it's just that it's so watered down for the mass public. God The Failed Hypothesis: How Science Shows that God Does Not Exist by Victor Stenger Probably one of the best books I've ever read. The Non-Existence of God by Nicholas Everitt Useful, but not something you read for thrills. The Black Hole War by Leonard Susskind Excellent book. I enjoy his thought experiments and presentations, and I think he did a fine job of putting emotion into the story. Godless by Dan Barker Excellent book, but his personally story is sad. Wow, my reviews are terrible compared to the above posts

To be honest, I have no idea. That's why I asked

That's why I wanted to make the distinction between in practice and in principle. You voted that time is infinite in the past and future. If this is the case, then aren't you disagreeing with the principle of your own objections? (Not calling you out, just trying to understand.) Do you think that something like a quantum field could have existed for infinite time?

I'm sure that the guy knows how tides work now; he probably went home and googled it. He probably knew what it was before he ever heard of Mr. O'Reilley, but a question that random probably threw him off-guard. But the fact of the matter is that atheists don't have to be smart or educated or know how things work. Like ydoaPs said, atheism is just the lack of belief in a god. Just because someone likes to talk about religion or debates religious people or anything like that, doesn't make them religious. If it did, then that would mean everyone is religious about anything they find interesting. Even though you said you would only call atheism a religion because it talks about God, it could easily be said that anything a person holds of great importance is their god. (In fact, I've seen christians say this first-hand.)

Well yeah, but isn't 'infinity' made of a bunch of finite things? Infinity may be a never ending number, but it still has the finite number 'one' in it... It would be finite because you would be dividing up that distance into fractions, not adding distance to the total displacement of my hand. I'm not trying to defend, what's it called, Zeno's paradox? Where a runner travels half the distance of a field, then half again, then half of that... What I'm saying is that all of those distances are a part of the total finite distance. But again, I could only prove this in principle, not practice. I think it is reasonable to say that since we can divide a centimeter into a millimeter, we could continue to divide that centimeter up into smaller and smaller segments. How would I reconcile the addition of another centimeter? Well, wouldn't the answer just be that there is an infinite number of infinitely small distances in between the two centimeters? I would think you couldn't, simply because you wouldn't keep the original point (in this case 1/8), but you would break up the original centimeter into 1/16. Eventually, you would just get an infinite number of infinitely small distances. (I've just started getting into the math of infinity, so forgive me if I'm making an error. I'm not trying to argue with you, I'm just trying to understand.)