Flat Definition and 469 Threads

Is it possible to get a near perfect flat surface with the roughness no more than 1-10 nm at any point? If it is, then how difficult is it?

what does it mean for the universe to be "flat"? What is the difference if the universe was flat or curved at all?

determine the minimum height of a vertical flat mirror in which a person 5'0'' in height can see his or her full image. I have absolutely no idea how to solve this type of problem... Since we don't know the distance between the object and the mirror, how in the world can we calculate the...

Inside a shell of matter I would experience a flat gravitational potential and hence no gravitational force. Is there any experiment I can do, short of leaving the shell, that could allow me to determine the existence of the potential? For example would my extra potential energy show up...

Have I got it right this time? Red-shifting is determined by the difference between the space-time curvature at the light source and the observer's space-time curvature. For the light source, all that matters is the distance from the center of gravity -- I think the motion of the source...

Closed spacetime with its dispersed masses and open spacetime under dark energy interfere dynamically at the Euclidean boundary. This zero curvature surface distinguishes where the cosmic geometry contracts from where it expands, and represents a significant unexplored structure within familiar...

My first post here, this question may have been asked before and answered already, if so a link would be appreciated. When we measure interstella distances are we measuring curved space distances or flat space distances? Putting it another way... Are we able to determine the curvature...

Studies of black hole physics by people like Hawking and Bekenstein suggests that our perceptual universe, which is perceived to have three spatial dimensions, might instead be "written" on a two-dimensional surface, analogously to a computer generated holographic projection. The everyday...

Just wondering what the general scientific community thinks about this topic.

We're doing a project for my engineering tech class, and i need to conduct a survey, we'd be really obliged if u could answer the survey questions. 1. When thinking about bridges, what is the first bridge that to your mind? 2. Why? 3. If crossing a bridge, do you look over the edge? 4...

Hi, I'm working on a kinematics problem of rolling a golf ball on a flat plane (4-position infinitesimally separated solution). The solution sought is to be planar, so we're working in 2D only. This is largely irrelevant though, as I'm facing a rather undergraduate puzzler. I need to...

The question is : A car travel in a flat circle of radius R. At a certain instant the velocity of the car is 18 m/s west and the total acceleration of the car is 2 m/s2 at 46 degrees north of west. What is R? I simply used a = v2/R and obtained 162 m. I suspected the question should be...

A car traveling on a flat circular track accelerates uniformly from rest with a tangential acceleration of 1.7m/s^2. The car makes it one quarter of a way around the circle before it skids off the track, Determine the coeficient of static friction between the car and track? I really have no...

Very interesting.

What exactly is the problem with a flat, finite universe? I've often heard it quoted that a flat universe must be infinite... but it's easy enough to design space-times that are perfectly flat yet are bounded. For example, S^1*S^1*S^1. What additional information is used to suggest a flat...

in this link Dr paul marmet states----- the universe is flat there is no space contraction there is no time dilation. http://www.Newtonphysics.on.ca/faq/flat-universe.html confirmation of non time dilation...

Just stumbled on the fact that Russia adopted a flat tax system about two years ago. Productivity rose rapidly afterwards and now at 10% growth per year. I reviewed Dick Armey's proposal wherein he uses a flat rate of 17% for all tax payers, but includes savings for being married, number of...

Most of the matter in our solar system lies roughly in a plane. I always wondered why. I imagine that there is a well understood reason for this, but I never came across it. I came up with this: Assume we have a large star nearing nova. It spins rapidly, and has a large magnetic field...

As far as I am aware scientists agree that the universe is flat, open or closed. However, if galaxies get further away from each other the gravitational attraction between them would decrease as the universe expands. Why is the universe speeding up not a real possibility?