Due any particle or body follow the same path, when starting from the same point in the same direction? This is not the case. The straightest reachable path is with photons, they have the maximum possible velocity, but still are influenced by the curvature of space.
For all other body the path is more bended under the influence of gravitational masses. It is possible to answer a question about does the light travel with different speed in space.
Near a black hole the photon runs slower from the point of view of a far away from this hole observer. So it is never possible to change the light speed in vacuum, which is the absolute upper limit for everything. In a strong gravitational field, the time passes slower, according to observers far away from the field. For observers affected by the field it is still c 0 though. And the space in this field is expanded, stronger the closer we get to the center of the field.
If we imagine space as 2D plane, we could say that it gets a deep dent where the mass is. The light ray that travels through this dent now travels perfectly straight in his view, but observers far away see a curved path because the space is curved. The noticeable "gravitational redshift" if light travels from an observer into a gravitational field or "blueshift" if light comes out of a gravitational field to an observer for external observers has its cause because the photon gathers energy while entering the gravity well while it loses energy when it leaves it.
This is potential energy, depending on the gravity potential the photon is located at. As masses create gravity wells with low potentials, the "absence" of a strong gravity field can be called high potential. This energy difference can't express itself in a speed difference kinetic energy , because we already said that light speed is constant. That means the photon's energy is proportional to its frequency.
An increase of the electromagnetic energy of the photon, because it enters a lower gravity potential and converts its potential energy, therefore results in a higher frequency, which is visible as a blueshift. What is happening is naturally quite relativ to the observer. Suppose you are sitting on the photon, travelling past the gravity source with the speed of light.
As has been argued above you would experience the force of the gravitational pull as an acceleration toward the source. Also, if you were to observe the passage of time during the journey, you would find that your clock is running slower than the clock of an observer travelling further away from the gravity source.
To this "further away traveller" you would therefore appear to be travelling faster, even though your both travelling at the speed of light. Ultimately, what this means is, while the gravity-source affects the path of the photon, the speed isn't affected due to the relative change in time. Sign up to join this community.
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Learn more. When you have a very fast particle traveling through a medium, that particle will generally be charged, and the medium itself is made up of positive atomic nuclei and negative electrons charges. The charged particle, as it travels through this medium, has a chance of colliding with one of the particles in there, but since atoms are mostly empty space, the odds of a collision are relatively low over short distances.
Instead, the particle has an effect on the medium that it travels through: it causes the particles in the medium to polarize — where like charges repel and opposite charges attract — in response to the charged particle that's passing through.
Once the charged particle is out of the way, however, those electrons return back to their ground state, and those transitions cause the emission of light. Specifically, they cause the emission of blue light in a cone-like shape, where the geometry of the cone depends on the particle's speed and the speed of light in that particular medium.
This animation showcases what happens when a relativistic, charged particle moves faster than light The interactions cause the particle to emit a cone of radiation known as Cherenkov radiation, which is dependent on the speed and energy of the incident particle. Detecting the properties of this radiation is an enormously useful and widespread technique in experimental particle physics.
Neutrinos hardly ever interact with matter at all. However, on the rare occasions that they do, they only impart their energy to one other particle. We can shield it very well from cosmic rays, natural radioactivity, and all sorts of other contaminating sources. And then, we can line the outside of this tank with what are known as photomultiplier tubes: tubes that can detect a single photon, triggering a cascade of electronic reactions enabling us to know where, when, and in what direction a photon came from.
With large enough detectors, we can determine many properties about every neutrino that interacts with a particle in these tanks. A neutrino event, identifiable by the rings of Cerenkov radiation that show up along the This image shows multiple events, and is part of the suite of experiments paving our way to a greater understanding of neutrinos.
The discovery and understanding of Cherenkov radiation was revolutionary in many ways, but it also led to a frightening application in the early days of laboratory particle physics experiments.
A beam of energetic particles leaves no optical signature as it travels through air, but will cause the emission of this blue light if it passes through a medium where it travels faster than light in that medium. Needless to say, this process was discontinued with the advent of radiation safety training. Still, despite all the advances that have occurred in physics over the intervening generations, the only way we know of to beat the speed of light is to find yourself a medium where you can slow that light down.
We can only exceed that speed in a medium, and if we do, this telltale blue glow — which provides a tremendous amount of information about the interaction that gave rise to it — is our data-rich reward. Until warp drive or tachyons become a reality, the Cherenkov glow is the 1 way to go! This is a BETA experience. You may opt-out by clicking here. The water waves are already traveling at their nominal speed the moment you start creating them. That is how waves behave.
Waves are created because a deformation in the material medium or in the field medium causes the medium to snap back towards the equilibrium state, but overshoot this state, and therefore end up oscillating back and forth, all the while yanking neighboring regions into the same motion. The wave speed is therefore determined by the medium's ability to snap back, and not by an external agent pushing the wave to accelerate it to different speeds.
Pushing harder on the medium just makes the crests of the waves taller. It does not make the wave travel faster through space. If the medium is constant across a region of space and across all frequencies of motion, then the wave speed will be constant through this region. In a region of uniform medium, a wave cannot accelerate. Your two values for the speed of the ball will be different; both correct for your frames of reference. Replace the ball with light and this calculation goes awry.
If the person on the train were shining a light at the opposite wall and measured the speed of the particles of light photons , you and the passenger would both find that the photons had the same speed at all times.
In all cases, the speed of the photons would stay at just under , kilometres per second, as Maxwell's equations say they should. Einstein took this idea — the invariance of the speed of light — as one of his two postulates for the special theory of relativity. The other postulate was that the laws of physics are the same wherever you are, whether on an plane or standing on a country road. But to keep the speed of light constant at all times and for all observers, in special relativity, space and time become stretchy and variable.
Time is not absolute, for example. A moving clock ticks more slowly than a stationary one. Travel at the speed of light and, theoretically, the clock would stop altogether. How much the time dilates can be calculated by the two equations above. In our example above, this would be the person in the train.
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