Questions tagged [special-relativity]
Questions regarding Albert Einstein's theory that posits, among other things, the equivalence of mass and energy.
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If astronomers didn't know about redshift could we still determine the universe is expanding?
What other evidence is there for the expansion of the universe?
Would the equations of physics look wrong without it?
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What does it exactly mean for spacetime to have no global symmetries?
Are there spacetimes or metrics with no global symmetries? Spacetimes/metrics with no global Poincaré, Lorentz, diffeomorphism, CPT, translational and gauge invariances?
And if there are, what does it ...
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Non-homogeneous and anisotropic metric and laws of physics...?
In this popular science article, they say that if our universe resulted to be non-uniform (that is highly anisotropic and inhomogeneous) then the fundamental laws of physics could change from place to ...
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Other Hubble spheres with no Lorentz symmetry?
Perhaps this may be a stupid question but anyways here it goes...
If the Lorentz symmetry is not global but rather local, wouldn't that mean that is possible that other Hubble spheres outside our ...
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Stellar aberration without relative motion between source and observer
According to SR, there should be no aberration if source and observer move uniformely (as would be the case in terrestrial aberration). In this case we should find at least some celestial bodies that ...
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Parker Solar Probe and clock correction
Due to the dynamic changes in speed and the value of the gravitational field in which the Parker Solar Probe stays, the clocks should have the errors due to relativistic effects.
https://physics....
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Measurement of Planetary Aberration (similar to stellar aberration)
It is often stated that, "Planetary aberration is a combined result of the observer's motion and the time taken for light to travel from a body in the Solar System to the observer". I am not ...
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It takes light roughly 8 minutes to travel to Earth from the Sun, but based on which perspective?
The passage of time is relative depending on whether one is the stationary observer or the object/particle traveling at the speed of light (or close to it). I get this, kind of. But, when we talk ...
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Do Einstein's ten field equations use 20 or 40 variables? (2 or 4 for each tensor equation?)
One site I came across says Einstein's 10 Field Equations use 20 variables, while another said 40.
There are four variables in spacetime - three for space and one for time, right?
But there are two ...
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Does one need to consider relativistic effects when simulating the (or any) Solar system?
There was a question over at Physics asking how to improve a home-brew numerical simulation of the Solar system.
Even though in that case the defects were likely numerical, I started to wonder whether ...
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Lunar Eclipse and relativity
I am currently working on A Depth Study for my year 12 Physics class, and am looking at relativity and time dilation of a lunar eclipse experience on the moon compared to as seen from on Earth. From ...
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Do relativistically measured rotation speeds (Special Relativity) change planetary mass slightly through Lorentz transformation?
Thanks @ConnorGarcia for your Answer. Avoiding 'Tidal Locking' for now - the rotational angular momentum Lrot is 10,000,000 times smaller, so negligible, but could it still be a factor in eccentricity?...
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Time of lunar eclipse relativity
Would there be a change in time in terms of the length of time it take for a lunar eclipse to cross the moon as seen from earth compared to as what would be experienced from the moons surface?
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Does the twin paradox work in an almost empty universe?
Background
The twin paradox is the popular thought experiment involving twins, one of whom makes a journey to a nearby star in a high-speed rocket (travelling at a velocity close to the speed of light)...
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Stellar Aberration and Lorentz Transformation
The aberration of starlight is claimed to result from the Lorentz transformation of Special Relativity, but I am having problems to understand this. Assume we have two reference frames $x,y,z$ (the ...
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What is the age of the universe if you were standing in a galaxy far far away such as GN-Z11?
If we agree with the universe starting from a Big Bang, 13.8 billion years ago, expanding at different rates governed by the Hubble constant of 67.4 km/s/Mpec, somewhere about 13.4 billion light years ...
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Faster than light?
From what popular science tells us, if I travel at close to the speed of light, I'd age slower.
So if I travel at 99% of SOL and travel the distance of one light year, for other people one year has ...
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Does time also pass more slowly for a galaxy that is traveling at relativistic speeds, where the speed difference is due to Hubble expansion?
If time passes more slowly, relative to Earth, for a traveler at relativistic speeds, say at .8c, traveling between stars inside this galaxy, does time also pass more slowly for a distant galaxy that ...
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Thinking about the Twin Paradox, what would a Twin Traveling at .8c, calculate as the amount his EBT aged at the mid-point in a 4 lightyear trip? [closed]
Referring to the twin paradox, where we have an Earth Bound Twin “EBT” and a Traveling Twin “TT” who travels away from Earth at velocity= .8c, lets say to Alpha Centauri, when the TT is half way ...
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How much time passes in the outside universe when falling into a black hole?
If someone were to jump into a black hole, looking back at Earth, how far into the future would they see of Earth? As I understand it, time would dilate approaching infinity as you approach the event ...
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Absolute zero speed in space [closed]
I have read multiple posts in here about the concept of an absolute zero speed definition in space. However, I have some arguments FOR absolute zero speed, which I would like to write here, and have ...
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Catching up with Hubble domain galaxy at constant acceleration: is it possible? If yes, what time will it be when I arrive?
An elf gave me a magic spaceship for Christmas: it can maintain a thrust of $\alpha = 10\ \mathrm{N/kg}$ indefinitely. Otherwise, I'm still constrained by physics. I plan to set out on a journey into ...
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How does time work beyond the cosmic event horizon?
The faster you move through space, the slower you move through time - the calculations show that as you approach lightspeed, time comes to a standstill.
How does time work beyond the cosmic event ...
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Lorentz transformation for stars
If a star that has regular pulses(standard candle) is flying away from us at relativistic velocity(very distant), would that pulses look like very sluggish compared to a non-relativistic velocity(...
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Is it possible to know if you are travelling close to the speed of light if you have nothing to compare your speed with?
This is a question that has been bugging me for some time. Let's see if I am able to make me understood!
Imagine you are travelling in a spaceship at 99.9999999999% the speed of light and you are ...
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Can anyone one show how speeds greater than c cause a paradox on a space time diagram?
So according to Relativity, time moves at different rates for different observers, and distant observers will actually disagree on the order of events. Now from what I gather this gets sorted out for ...
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Dropping a pebble into a black hole [duplicate]
If one were to drop, say, a pebble, from a sufficient distance, into a black hole. The pebble would continue to accelerate until it were just short of the speed of light. In the next moment it's speed ...
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Are there any examples where the transverse doppler effect is applied in astronomy?
Are there any astronomical examples where the transverse doppler effect(Horizontal doppler effect) is applied (Derives a meaningful result)?
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What exactly is the cosmic definition of ‘now’ is?
There is no cosmic definition of now because of special relativity, because of rate at which time flows for a particular object depends upon your point of view and your velocity. For a rocket ...
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Do gravitational waves have distinct bands or parameters from which a source redshift can be inferred? [duplicate]
In optical astronomy, much (most?) electromagnetic radiation is emitted at well defined frequencies, and this can be used to infer a redshift for the source, and hence its recessional velocity, age, ...
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Information speed and our view of the cosmos
It is common knowledge that when we look at the stars we look back in time. And most stars are thousands of lightyears away from each other. The information that photons cary about the position of a ...
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Does Absolute Velocity Exist?
It seems everyone is on the same page about there being no "absolute velocity" due to the fact that everything is relativistic. However, this leaves me confused. This seems to be disconnected with the ...
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is this really true that speed of light is same as we look from different parts of universe?
According to the theory of relativity. The speed of light is same for every observer. But how can we know that this applies to more than a local region? What if light travelled to us from a distant ...
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Contradiction of special theory of relativity and quantum mechanics
Why do special theory of relativty (with the core message of E=mc²) and quantum mechanics do not go together? Why is the special theory of relativity in the quantum model not valid?
Can anyone list ...
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Does a 4-manifold universe imply zero net energy?
If our universe is a 4-manifold (i.e. with every point in space-time already existing) does this imply that there is zero net energy (as net energy would do work and so change the universe)?
If so, ...
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How old would I be if I travelled 1000 light years in one year
If I were to travel 1000 light-years, and witness only 1 year elapse in my frame of reference, how much time would have passed in the frame of reference of the Earth?
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What is length of the universe on lights perspective
According to Einsteins theory of special relativity, when something is travelling close to light speed, travel path is contracted. When the traveller is light itself, does it see the travel path ...
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Have we Observed Continuum Emission from Neutron Stars?
Have we detected continuum optical emission from any rotating neutron stars that do not have an accretion disk dominating the light? I ask because I know we have observed Doppler broadening of ...
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Relative black hole?
When some object is moving, it appears smaller and more massive. What if it's moving so fast it should become a black hole? Some calculations:
Let observed radius $R_0\gamma$ ($R_0$ - radius at rest) ...
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How fast would we have to go for the red(/blue)shifts of galaxies ahead of us to differ from those behind us with statistical significance?
Here, we are looking for a statistically significant difference between the mean redshifts of galaxies ahead and those behind, with reference to a prior-specified direction. For example, suppose that ...
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Black hole darkness a result of gravity or temporal distortion?
Please correct me if I am wrong as I may have made some incorrect assumptions.
Okay so we know that at some stage of "nearness to a black hole", light is no longer reflected back at us from the black ...
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What is the equation of state for a relativistic fluid/gas?
Say we have a relativistic fluid/gas, as we have in some astrophyical systems.
Now let us write:
$e$ - energy density in the fluid's rest frame.
$P$ - pressure in the fluid's rest frame.
$n$ - ...
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How long would it take to reach the edge of the reachable universe?
How long would it take to reach the current edge of the reachable portion of the universe, with the following bounds in mind:
We figure out a way build a space ship to provide a constant 1 G ...
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Photon Paradox?
Imagine a photon reaching the Hubble Space Telescope today had originally been emitted from a star in the early universe 13 billion years ago. Einstein’s Special Relativity tells us, traveling at the ...
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Light that travels eternally because of inflation?
What happens with electromagentic waves that are emitted into
intergalactic space, but reach not any object because of inflation? Lets assume that photon A and photon B are emitted. Photon B hits ...
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How far into the future can we go by traveling close to a black hole?
If we sent someone on a path that passed as near as possible to a black hole without getting pulled in, how far into the future would they go due to time dilation? Let's assume the black hole is 5 ...
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Special Relativity as Applied to an Interstellar Starship?
I'm once again confused by the twin paradox. Let's say I am on an interstellar starship flying at 0.6c from a star 30 light years away from Earth to a star 50 light years away from Earth and 40 light ...
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Observing a point 13.82b ly away, 1b years ago
I understand that we can observe far away galaxies to get an idea how the universe looked like in the past.
Assuming the universe is 13.82b years old, would it be correct to say that if we looked at ...
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Gravity assist: why is the velocity doubled? [closed]
The Wikipedia article has this terrestrial analogy:
Imagine standing on a train platform, and throwing a [tennis] ball at 30 km/h toward a train approaching at 50 km/h. The driver of the train sees ...
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What is the bulk Lorentz factor?
When we are talking about relativistic motions, say from a relativistic jet, what is meant by the term "bulk Lorentz factor", and the bulk speed, $\beta$?
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