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• #### A reply onConversation: If gravity bends light, how do we know we're not looking at the same old light going round and round in circles?

Jul 24 2013: How rude!

You have some very deep misconceptions about mathematics if you think it can be used as evidence of anything. It's a description of a model, nothing more. It can be used to make predictions, but even that's not real proof. It's impossible to prove a theory right. It can only be proved wrong. All you can do is say that the data matches the model. To do that the model needs to be unambiguous. That's what mathematics is for.

You need to forget schooling because it obviously didn't work properly and learn to think for yourself. Good luck.
• #### A reply onConversation: If gravity bends light, how do we know we're not looking at the same old light going round and round in circles?

Jul 22 2013: What? Mathematics isn't proof of anything. It's just a way to tighten a description because maths is totally unambiguous and isn't open to interpretation.

Are you talking about the mathematics of a hypersphere? That's already known. If you're talking about the difference between the mathematics of describing the universe in this way vs the maths of describing it beginning from a gravitational singularity then there's no difference because from our perspective the universe does shrink into a singularity as we look back into the past, because it's a sphere. It's not just what it looks like from our perspective, it's what actually happened from our perspective, but that's not what it would look like if we were there. It would look just like this.

It makes so much more sense than thinking the universe is actually smaller in the past. As we look across the curved surface objects get more red-shifted as we're looking across more of a curved surface. If we look far enough in any dimension then everything funnels into a singularity. Look up dark flow.
• #### A reply onConversation: If gravity bends light, how do we know we're not looking at the same old light going round and round in circles?

Jul 9 2013: "Yes but that does not state, nor prove, in anyway shape or form that the universe is of that nature."

No it doesn’t. You were saying you were having trouble visualising it. String theory isn’t needed for the universe to be spherical. That’s the only way it can make sense imo. I don’t believe in infinity in any real sense and I don’t see the universe having edges somehow, so that’s the only way I think it can work. Relativity doesn’t prove it but it definitely suggests it.
• #### A comment onConversation: How do you overcome a lapse in creativity?

Jul 9 2013: True creativity can’t be forced. When it’s working it’s no effort at all. The more you try to force it the further away it gets. It feels like I’ve got cotton wool stuffed in my head when that happens. Do something completely non-creative until you feel clear headed again. Sometime it takes days. That’s how it works with me anyway.
• #### A reply onConversation: If gravity bends light, how do we know we're not looking at the same old light going round and round in circles?

Jul 8 2013: I'm going to try explain it more clearly. Feel completely free to not reply to this post if you've had enough, I'm doing it for myself and for anyone reading this thread who might be interested. Please don't think I'm being condisending. I know that it can hard to get your head round this if you're not used to thinking in those terms and I'm trying to simplify and condense something that is unlike anythink we're used to in every day life, but it is actually very simple. I'm not trying to show off or anything by saying that. It really is simple, but it's sometimes very difficult for us to rap our heads around a concept that our normal lives haven't conditioned us to understand.

I never said in two dimensional space. I think the problem is still that you're thinking flat means two dimensional. Flat in this context is how people normally think of space and time, ie every observer agrees on the distances between objects and the passage of time moves at the same rate for everyone. Curved means that there's a mass and observers closer to that mass measure distances between the same objects as shorter than those who are further away from the mass and also observers closer to the mass measure time moving at a slower rate, so those closer to a mass will appear to be moving through time at a slower faster rate from the perspective of a more distant observer and those further away will appear to be moving through time at a faster rate from the perspective of an observer closer to the mass. One very pretty way of describing this is objects following straight paths through curved space-time. I hope that helps a bit.
• #### A reply onConversation: If gravity bends light, how do we know we're not looking at the same old light going round and round in circles?

Jul 8 2013: Just imagine that straight lines eventually lead back to their starting point if you travel far enough. If it's spherical then it's the same distance in every direction until you arrive back at the starting point, including in time if it's a four dimensional sphere (hypersphere).
• #### A reply onConversation: If gravity bends light, how do we know we're not looking at the same old light going round and round in circles?

Jul 8 2013: No of course I don't deny that. What does it have to do with this?

The point is that in flat space-time all observers will agree on the distances between objects and in curved space-time they won't. If an observer draws a grid of squares in one flat pain and then does the same at a right angle to it they would get a three dimensional grid of cubes and in flat space-time all observers would agree. They'd all say they were all cubes, but that's not true in curved space-time. If an object close to a gravitational source did this then an object further away from it would see the same grid as warped because the distance in space-time is shortened for the object closer the mass, so they'd also be moving through time at a slower rate compared to the further object, but the closer one wouldn't notice anything unusual because it's relative.

Distances aren't absolute. Observers measure different distances in the same space and time depending on the frame of reference. Space and time aren't a fixed background. They're an interconnected and dynamic background that are defined by the objects in it and measured differently by different observers depending on their point of view, and no-one is more or less right than anyone else. They're all right from their own perspective. Pretty isn't it.
• #### A reply onConversation: If gravity bends light, how do we know we're not looking at the same old light going round and round in circles?

Jul 7 2013: No, space-time is four dimensional (at least), whether it's flat or not. You're misunderstanding slightly what flat and curved means in this context. Flat simply means free of gravitaional acceleration in gr and curved means it isn't. Space-time is curved towards mass, which is another way of saying that gravity is a shortening of the distances in space and time (length contraction and time dilation) and the effect falls off as a inverse square of the distance. In zero dimensions it would be infinite, in one it wouldn't weaken with distance, in two if you double the distance it would be halved, and in three spactial dimension it's an inverse square (if you double the distance it's devided by four). It's simply the way it spreads out and becomes more difuse as it covers a larger volume.
• #### A comment onConversation: a quit smoking commercial that mocks the idea that cigarettes are cool

Jul 7 2013: How about a pro smoking advert that mocks the idea that smoking = an automatic death sentance and highlights the benifits of stress relief?
• #### A reply onConversation: If gravity bends light, how do we know we're not looking at the same old light going round and round in circles?

Jul 7 2013: If the space-time is flat then the light will expand in all directions at the same rate, which makes an expanding sphere with the light source at the centre. If the space-time is curved then the light will move at the same speed in all directions but not at the same rate in all directions from a non-local perspective because time dilation and length contraction will cause distance in that direction to decrease (that's what curved space-time means), so you get a warped bubble of expanding light.

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