Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: benm on 29/03/2019 15:22:53

Salman wants to know:
It seems every object in the universe is in motion.Why motion is so embedded fundamentally in spacetime fabric? Is they any object in the cosmos that is standstill?
Can anybody help?

Motion is relative to the observer, so whether an object is standing still or not depends on the defined reference frame.

The big bang created a universal motion nothing standstill.

Motion is relative to the observer, so whether an object is standing still or not depends on the defined reference frame.
Why is it that light (in a vacuum presumably) has no reference frame?
An observer moves wrt to a beam of light but the beam of light does not move wrt to the observer?
Mightn't one imagine that one would imply the other ?
Or is it simply that a reference frame of light would involve infinities and so is mathematically unmanageable?

Vector every piece of mass energy in the universe, relitavley speaking there has to be a stationary.

...... relitavley speaking there has to be a stationary.
Relative to what?

An observer moves wrt to a beam of light but the beam of light does not move wrt to the observer?
A beam of light does move relative to the observer. Switch on a torch and the leading edge of the beam moves away at the speed of light.

Motion is relative to the observer, so whether an object is standing still or not depends on the defined reference frame.
I think the OP refers to motion with respect to a point in space or kinetic energy for the object equals zero.

I think the OP refers to motion with respect to space.
If there is nothing else in that space, you can't know whether you are moving at a constant speed or are at rest.

I think the OP refers to motion with respect to space.
If there is nothing else in that space, you can't know whether you are moving at a constant speed or are at rest.
Supposing gravity extends to infinity no object is at stationary with respect to a point in space.
I have an opinion that gravity is limited even though the big bang gave motion to every object.

Supposing gravity extends to infinity no object is at stationary with respect to a point in space.
It isn't meaningful to say that something is moving or stationary with respect to a point in space. You can only measure your motion relative to other objects.

Supposing gravity extends to infinity no object is at stationary with respect to a point in space.
It isn't meaningful to say that something is moving or stationary with respect to a point in space.
What do you call an object with kinetic energy equals zero?
Or with relativistic mass equals rest mass.

What do you call an object with kinetic energy equals zero?
The measured kinetic energy of an object is relative to the observer. If you measure it to be zero, then that means it is stationary in your particular reference frame. It wouldn't be zero in a different reference frame.

What do you call an object with kinetic energy equals zero?
The measured kinetic energy of an object is relative to the observer. If you measure it to be zero, then that means it is stationary in your particular reference frame. It wouldn't be zero in a different reference frame.
You mean an object at stationary on earth has kinetic energy equals zero?No since it is in motion with the earth movement.

You mean an object at stationary on earth has kinetic energy equals zero.No since it is in motion with the earth movement.
It would have zero kinetic energy as measured in the reference frame of Earth's surface. As measured by someone on the Sun, it would not have zero kinetic energy.

You mean an object at stationary on earth has kinetic energy equals zero.No since it is in motion with the earth movement.
It would have zero kinetic energy as measured in the reference frame of Earth's surface. As measured by someone on the Sun, it would not have zero kinetic energy.
How you would measure kinetic energy twice differently? kinetic energy is what energy an object contains, So what is the actual kinetic energy the object contains?

How you would measure kinetic energy twice differently?
By moving between two different reference frames.
kinetic energy is what energy an object contains,
That value changes between reference frames.
So what is the actual kinetic energy the object contains?
That depends on what reference frame you are measuring it from.

...... relitavley speaking there has to be a stationary.
Relative to what?
Relative to the entireity, the universal total.

An observer moves wrt to a beam of light but the beam of light does not move wrt to the observer?
A beam of light does move relative to the observer. Switch on a torch and the leading edge of the beam moves away at the speed of light.
Yes,don't know what I was thinking.

There is an ongoing experiment in the UK to create a complete lack of motion. It is conducted in a tunnel under London. One surprising finding is that, although clocks/watches work as normal, observers perceive time to be standing still. I think it's called the northern line.