F L A T E A R T H
“There ought to be something very special about the boundary conditions of the universe and what can be more special than that there is no boundary?”
STEPHEN HAWKING
STEPHEN HAWKING
It seems that Galeleo was giving the poor old Inquisition all that hasstle for nothing.
The truth is that they were both right; and their little difficulty was almost certainly founded on a confusion of terminology. To the great astronomer 'world' equated to 'planet' whereas it meant 'universe' to the theologians. The Inquisition, it turns out, was simply thinking bigger picture.
According to no less an authority than NASA the universe is absolutely flat. Which doesn't help with the pre-copernican mariner's question...
"What happens if your ship (or space ship) gets too close the edge?"
Here's what NASSA says on the subject...
The truth is that they were both right; and their little difficulty was almost certainly founded on a confusion of terminology. To the great astronomer 'world' equated to 'planet' whereas it meant 'universe' to the theologians. The Inquisition, it turns out, was simply thinking bigger picture.
According to no less an authority than NASA the universe is absolutely flat. Which doesn't help with the pre-copernican mariner's question...
"What happens if your ship (or space ship) gets too close the edge?"
Here's what NASSA says on the subject...
The density of the universe determines its geometry. If the density of the universe exceeds the critical density, then the geometry of space is closed and positively curved like the surface of a sphere. This implies that initially parallel photon paths converge slowly, eventually cross, and return back to their starting point (if the universe lasts long enough). If the density of the universe is less than the critical density, then the geometry of space is open (infinite), and negatively curved like the surface of a saddle. If the density of the universe exactly equals the critical density, then the geometry of the universe is flat like a sheet of paper, and infinite in extent.
The simplest version of the inflationary theory, an extension of the Big Bang theory, predicts that the density of the universe is very close to the critical density, and that the geometry of the universe is flat, like a sheet of paper.
The WMAP spacecraft can measure the basic parameters of the Big Bang theory including the geometry of the universe. If the universe were flat, the brightest microwave background fluctuations (or "spots") would be about one degree across. If the universe were open, the spots would be less than one degree across. If the universe were closed, the brightest spots would be greater than one degree across.
Recent measurements (c. 2001) by a number of ground-based and balloon-based experiments, including MAT/TOCO, Boomerang, Maxima, and DASI, have shown that the brightest spots are about 1 degree across. Thus the universe was known to be flat to within about 15% accuracy prior to the WMAP results. WMAP has confirmed this result with very high accuracy and precision. We now know that the universe is flat with only a 0.5% margin of error.
This suggests that the Universe is infinite in extent; however, since the Universe has a finite age, we can only observe a finite volume of the Universe. All we can truly conclude is that the Universe is much larger than the volume we can directly observe.
The simplest version of the inflationary theory, an extension of the Big Bang theory, predicts that the density of the universe is very close to the critical density, and that the geometry of the universe is flat, like a sheet of paper.
The WMAP spacecraft can measure the basic parameters of the Big Bang theory including the geometry of the universe. If the universe were flat, the brightest microwave background fluctuations (or "spots") would be about one degree across. If the universe were open, the spots would be less than one degree across. If the universe were closed, the brightest spots would be greater than one degree across.
Recent measurements (c. 2001) by a number of ground-based and balloon-based experiments, including MAT/TOCO, Boomerang, Maxima, and DASI, have shown that the brightest spots are about 1 degree across. Thus the universe was known to be flat to within about 15% accuracy prior to the WMAP results. WMAP has confirmed this result with very high accuracy and precision. We now know that the universe is flat with only a 0.5% margin of error.
This suggests that the Universe is infinite in extent; however, since the Universe has a finite age, we can only observe a finite volume of the Universe. All we can truly conclude is that the Universe is much larger than the volume we can directly observe.