How fast are we moving when standing still?
Earth is moving around sun in an orbit with mean radius 1AU. Time of one revolution is 1 year . Thus, its speed is $$ v \approx 2 \pi \dfrac{1AU}{1year} = 30km/sec $$ Sun moves around galactic center at a speed of $ v'=220km/sec$. Thus, when you are standing still on Earth,you can have a velocity of $v'+v$ $\textit{with respect to center of Milky way galaxy}$. This value lies in the range of $[220-30,220+30] km/s$ (since velocities are added vectorially). This value is used when you can make an assumption that our galaxy is at rest.
From cosmological point of view, our galaxy is moving around other galaxies. An absolute frame of reference can be $\textit{ Cosmic background radiation}$, which is supposed to be constant throughout the space. With CMBR as reference frame, the speed of Earth measured by COBE(cosmic background explorer), is $360+/- 20 km/s$.
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Geruta
Updated on January 12, 2020Comments
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Geruta almost 4 years
The Earth rotates around itself and revolves around the Sun. Our solar system revolves around the center of our galaxy and our galaxy is moving in some way throughout the universe. If you took into account all this, how fast would you be going just standing still? Can we even calculate such a value giving that there is no static point in the universe to which we can measure ourselves against?
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SchrodingersCat about 8 yearsFast with respect to what?
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Geruta about 8 yearsI'm looking for a quantifiable value. Either KM/H or MPH
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Geruta about 8 yearsI also know that at certain times, these values would counter each other or enhance each other. So while there isn't one specific value of speed we move it, there is a range that should be able to be averaged into a generic speed.
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SchrodingersCat about 8 yearsPerhaps you misunderstood me. Its not the unit I am talking of. There is nothing known to be in absolute rest in this universe. So we can only measure things relative to other things. So I was asking "fast relative to what?"
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Geruta about 8 yearsSo then it's not possible? I added that bit of my question at the end "is it even possible to measure such a value given that there is no absolute static point with which to measure ourselves against?"
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Geruta about 8 yearsWhat about measuring yourself against the constantly receding edge our our universe (background radiation)? Could you determine the center of an object by where and how fast it's edges grow away from the center?
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CoilKid about 8 yearsThe problem with that, we don't really know where the edge of the universe is, let alone whether it has one. Also, your ruler would be expanding as well, so any measurement would stay constant.
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Qmechanic about 8 yearsPossible duplicates: physics.stackexchange.com/q/4493/2451 , physics.stackexchange.com/q/154426/2451 and links therein.
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Geruta about 8 yearsIs it safe to say then that we will never visit the same point in the universe more then once? What I mean is, if you could plot an x,y,z graph of our universe and the distance between each point was the size of one average sized human being, you would never visit the same exact point more then once because we are always moving around the earth, sun, Galaxy, and throughout the universe.
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WillO about 8 yearsWhat does "same point" mean?
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seeking_infinity about 8 years@Geruta This question is not valid. Let's say you are at a point A(x,y,z) in universe at some time t1. Now, universe is expanding. After some years, that A is not a point anymore but has been stretched over to make some volume. The point I want to make is, universe is changing every sec. So, you can never return to the same point because it will not exist anymore.
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Gert about 8 years@seeking_infinity: $v= \dfrac{1AU}{1year} = 30km/sec$ is a misleading formula, even though you have the right outcome. I strongly suggest to edit.
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Admin almost 8 yearsthe CMB is absolutely not an absolute background
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seeking_infinity almost 8 years@igael To calculate velocity, we need a reference frame as velocities are always relative. I have chosen two frames and calculated velocities wrt them. I didn't say that any of them is absolute rest frame.
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Admin almost 8 yearsit is what I understood, but the sentence is a little ambigous. TY