we need a *physics channel

*promote

Promoting this video and sending it back into the queue for one more try; last queued Thursday, October 28th, 2010 4:05am PDT - promote requested by kulpims.

Surely that just falls under the "science" channel as a whole... otherwise we'll need chemistry and biology too >> ^kulpims:

we need a physics channel

I hope with more accuracy it still comes out flat. It would be so nice to have our entirety as Euclidean, makes the maths soooo much easier and gives my perception a break from all that 'curved space' mind bending.

*spacy <-- There's your astronomy channel.

Adding video to channels (Spacy) - requested by thegrimsleeper.

...I did that math in my head years ago, I just didn't feel the need to write it down and show people!

I got a feeling his discussion was unravelling around 2m30s into the video

[redacted]

>> ^Mcboinkens:

Misleading. He is saying density is directly related to shape. What exactly qualifies as flat in the view of shapes? That implies that the Earth if flat too. I have a feeling there is quite a bit of debate about the process used here to determine it is flat and not saddled.


More over, what is it say it isn't changing or is due to change, or is always in a state of flux. There might be some other more fundamental rule governing that overall shape...or what if the same isn't consistent through the galaxy. And is shape something you need to confine to matter and not the container in which mater is in? If both have a shape, and ones shape is affecting the others shape, what does shape even mean anymore. Is the shape the thing you have, or is it the thing you have after the thing above you is taken into account. What is shape?

My metaphysical interpretation of the universe is non-dimensional. Space having depth, IMO, is a result of the minds interpretation of the details of the universe. While the elements (heheheh) of Euclid's geometry are completely sound, and thus, trying to talk about the shape of the universe as humans experience it will be a question that has an answer, it doesn't answer the more important question, does existence itself have dimension. In the same way that I don't believe color is a property of light, I think you can reduce space and time (though time gets interesting) to an experience of minds.

Even without my own metaphysical framework built up, all interpretations of space (lines, squares, rays) derive their existence from one essential element, the point. A point has no dimension. A line is essentially a collection of dimensionless points. It is not necessary to interpret them as something with dimension. For example, y=x. Algebra, in general, allows for a dimensionless explanation for the interaction of points. Y=x doesn't have to look like anything, per say, for it to be solved in algebra. While humans will retain the contextual information of space and shapes when working for algebra, those are interpretations that correlate back on the human reality. In other words, much akin to a computer program, the universe could (and I believe does) operate without a property of space. Space is a result of minds in the same way monitors construct visual images from a computer. Both are interpretations of dimensionless data.

Seeing in spaces helps us be better hunters, but as that confers to the ultimate truth of reality, I am less certain. The real story might be less about space and gravity, but the overall governing dynamics which exist as a simple set of seemingly arbitrary rules. The reality of the universe might be very closely understood as a computer program or a very sophisticated algebra expression.

It isn't misleading. He's just using the best language available for a popular description of the issue. The universe's mean density determines directly the curvature of the spacetime manifold; so it isn't so much describing shape as geometry. A triangle's still a triangle in a curved spacetime but the geometric properties (sum of the angles) changes. 'Flat' as we think about it doesn't work terribly well in describing a 4-dimensional manifold but still accurately describes the flat spacetime as being one without curvature - or asymptotically Euclidean.

>> ^Mcboinkens:

Misleading. He is saying density is directly related to shape. What exactly qualifies as flat in the view of shapes? That implies that the Earth if flat too. I have a feeling there is quite a bit of debate about the process used here to determine it is flat and not saddled.

[redacted]

I get the feeling this is dumbed down to the point where it can be argued about - maybe the real information is indisputable. But anyway - this might be completely unrelated, but i was shown today by my maths lecturer that if you're "infinitely" far away from a curve, you're equidistant from each point on that curve, so a curve is actually a straight line.

Maybe i didn't follow the video well enough, but it seemed to show a satellite looking out at a section of the sphere we draw around ourself and label "the earliest radiation". How can we look at a surface that is billions of light years away and tell whether or not it has curvature? And if i assume that we CAN see a difference in distance to see whether it's flat or not, surely our error margins are comparatively so large that we couldn't state either way for certain?

I'm going to assume that it's visually extremely hard to demonstrate the principle visually, and that ^ isn't the point.

Your points are both well made and entirely pointless regarding the video. I say that not as an insult but as someone who sees things much as you suggest. The crux is, though, that the same can be said for all of science together. The dissecting of space into abstracts of meaning is no different from any other abstraction that people do. The trouble is, and where I think your description is too simple is that the abstraction and the dynamics are one in the same. The geometry they're trying to get down to in the video here describes the base dynamics of gravity throughout the universe. In that sense, it isn't just a structure applied to the universe by human minds but something fundamental. Describing gravity as a curvature in space time could be considered a human abstraction (like the electromagnetic field or the wave function in quantum mechanics) but the issue of whether the mean gravitational background of the universe is flat or not goes beyond that. Just like the mass and charge of the electron. It's a fundamental; it is the dynamics, the flow.


>> ^GeeSussFreeK:

More over, what is it say it isn't changing or is due to change, or is always in a state of flux. There might be some other more fundamental rule governing that overall shape...or what if the same isn't consistent through the galaxy. And is shape something you need to confine to matter and not the container in which mater is in? If both have a shape, and ones shape is affecting the others shape, what does shape even mean anymore. Is the shape the thing you have, or is it the thing you have after the thing above you is taken into account. What is shape?
My metaphysical interpretation of the universe is non-dimensional. Space having depth, IMO, is a result of the minds interpretation of the details of the universe. While the elements (heheheh) of Euclid's geometry are completely sound, and thus, trying to talk about the shape of the universe as humans experience it will be a question that has an answer, it doesn't answer the more important question, does existence itself have dimension. In the same way that I don't believe color is a property of light, I think you can reduce space and time (though time gets interesting) to an experience of minds.
Even without my own metaphysical framework built up, all interpretations of space (lines, squares, rays) derive their existence from one essential element, the point. A point has no dimension. A line is essentially a collection of dimensionless points. It is not necessary to interpret them as something with dimension. For example, y=x. Algebra, in general, allows for a dimensionless explanation for the interaction of points. Y=x doesn't have to look like anything, per say, for it to be solved in algebra. While humans will retain the contextual information of space and shapes when working for algebra, those are interpretations that correlate back on the human reality. In other words, much akin to a computer program, the universe could (and I believe does) operate without a property of space. Space is a result of minds in the same way monitors construct visual images from a computer. Both are interpretations of dimensionless data.
Seeing in spaces helps us be better hunters, but as that confers to the ultimate truth of reality, I am less certain. The real story might be less about space and gravity, but the overall governing dynamics which exist as a simple set of seemingly arbitrary rules. The reality of the universe might be very closely understood as a computer program or a very sophisticated algebra expression.

To McBoinkens:
The 4th dimension didn't play into what they are saying directly but it is inseparable from the physics. I was merely pointing out that you were taking their language regarding 'shape' and 'flatness' too literally. Your point regarding reworking of our understanding of gravity is a perfect example. The real question addressed by this video is what is the overall curvature of the universe? The local behavior will be dominated by the local distribution of mass, but what shape does it take asymptotically as you move away from local sources? It doesn't require a re-working of our current theory of gravity and is, in fact, inextricably tied to it. If gravity is related to a bending in the manifold of spacetime than what is the background geometry of the universe? Is it flat or something else? Their analysis did involve the fourth dimension (time) because you can't separate it from any discussin of gravity (or physics in general for that matter). The microwave radiation they measured travelled through both space and time to arrive at the satellite acquiring the data. In that way, it is a measure of the spacetime that it travelled through along the way and they use it to determine the basic geometry of the universe.

To dannym:
I didn't think it was dumbed down that badly. In fact, I thought it was quite well presented. Here again, the curvature they're measuring is the baseline for the universe at large. There are a number of reasons to expect the universe to be flat; not the least of which because it's the most intuitively pleasing. The point is if the universe has a mean curvature to it than that curvature is everywhere including right in front of your face. They aren't measuring the curvature of some incredibly distant point but looking at the most ancient radiation within the universe and the distribution of it to determine the basic geometry of all that is.

>> ^Mcboinkens:

>> ^crotchflame:
It isn't misleading. He's just using the best language available for a popular description of the issue. The universe's mean density determines directly the curvature of the spacetime manifold; so it isn't so much describing shape as geometry. A triangle's still a triangle in a curved spacetime but the geometric properties (sum of the angles) changes. 'Flat' as we think about it doesn't work terribly well in describing a 4-dimensional manifold but still accurately describes the flat spacetime as being one without curvature - or asymptotically Euclidean.
>> ^Mcboinkens:
Misleading. He is saying density is directly related to shape. What exactly qualifies as flat in the view of shapes? That implies that the Earth if flat too. I have a feeling there is quite a bit of debate about the process used here to determine it is flat and not saddled.



I don't se how the 4th dimension even played into their analysis. It's not like they measured time through density. It seemed to me like they were trying to describe the observable 3 dimensional literal space as flat, which is why I thought it was misleading. If they were saying spacetime was flat, I disagree even further because that would completely screw up our current theory of gravity as a function of spacetime. Which is fine in itself, but not without coming up with a replacement for that idea first.


>> ^dannym3141:

I get the feeling this is dumbed down to the point where it can be argued about - maybe the real information is indisputable. But anyway - this might be completely unrelated, but i was shown today by my maths lecturer that if you're "infinitely" far away from a curve, you're equidistant from each point on that curve, so a curve is actually a straight line.
Maybe i didn't follow the video well enough, but it seemed to show a satellite looking out at a section of the sphere we draw around ourself and label "the earliest radiation". How can we look at a surface that is billions of light years away and tell whether or not it has curvature? And if i assume that we CAN see a difference in distance to see whether it's flat or not, surely our error margins are comparatively so large that we couldn't state either way for certain?
I'm going to assume that it's visually extremely hard to demonstrate the principle visually, and that ^ isn't the point.

@crotchflame i seem to be being misunderstood everywhere today. I didn't mean they'd dumbed it down too much and it was thus bad, i meant that even to someone who's not completely uninitiated, it was difficult to follow the explanation, whereas i imagine a demonstration of the principle with a bit of the maths would explain it much better.

As for the rest of your comment - as i said before, that's the impression i got from the video which showed a satellite looking at a flat surface. Was that a poor representation of the principle, then? I thought the whole point was that they were looking at a 'surface' - whatever that surface is - and seeing if it was flat or not.