# Gravitational waves analogous to photons and EM radiation?

• keepit
In summary: Not to be argumentative or semantic but if spacetime can curve how can it be nothing.Is "curvature" just a figure of speech?No, "curvature" is a real physical phenomenon.

#### keepit

Are gravitons and gravitational waves analogous to photons and EM radiation?

In a sense yes. Keep in mind that gravitational waves are dominated by higher order multipole terms than electromagnetic waves are.

Since gravity bends EM radiation, why would it not also slow down EM radiation?

All kinds of weird effects can happen to EM radiation on a global scale due to curvature of space-time. It only travels at ##c## relative to inertial observers on a local scale.

Not to be argumentative or semantic but if spacetime can curve how can it be nothing.
Is "curvature" just a figure of speech?

keepit said:
Not to be argumentative or semantic but if spacetime can curve how can it be nothing.
Is "curvature" just a figure of speech?

The curvature is most certainly not a figure of speech - it's real.

You can detect curvature by looking for things like parallel lines that intersect (if I draw two parallel lines at the equator and pointing due north they'll intersect at the north pole) and triangles whose interior angles don't add to 180 degrees.

It's something of a jump to conclude that the presence of these curvature effects means that spacetime has to be "something" instead of "nothing". All we really have is a mathematical object (the "metric tensor") that tells us the distance between two nearby points; large-scale effects like the intersecting or not of parallel lines are derived from the metric. Some metrics correspond to flat manifolds and others to curved ones; neither tell us much about whether there's something there to curve.

keepit said:
Not to be argumentative or semantic but if spacetime can curve how can it be nothing.
Is "curvature" just a figure of speech?

This is highly dependent on what "nothing" means.

Consider that we cannot detect spacetime, we cannot measure it, cannot touch it, etc. We can only detect and interact with things within spacetime, which is why its called the "framework" that everything sits within. If you want to go ahead and say that spacetime is "something", then feel free. Just realize that your definition of "nothing" and "something" may be different than someone else's. In the end whether you call it nothing or not changes, well, nothing. It's just arguing over definitions.

## 1. How are gravitational waves similar to photons and electromagnetic radiation?

Gravitational waves, like photons and electromagnetic radiation, are a form of energy that travels through space at the speed of light. They also have a wave-like nature and can be described by a mathematical equation known as the wave equation.

## 2. What is the source of gravitational waves?

Gravitational waves are produced when massive objects, such as black holes or neutron stars, accelerate or change their motion. This causes ripples in the fabric of space-time, similar to how a stone creates ripples in a pond when thrown in.

## 3. Can we detect gravitational waves?

Yes, gravitational waves have been detected through the use of advanced technology such as the Laser Interferometer Gravitational-Wave Observatory (LIGO). This involves measuring extremely small changes in the length of two perpendicular laser beams caused by passing gravitational waves.

## 4. How are gravitational waves different from photons and electromagnetic radiation?

One major difference is that photons and electromagnetic radiation can travel through a vacuum, while gravitational waves require a medium, such as space-time, to propagate. Additionally, gravitational waves are affected by the curvature of space-time, while photons and electromagnetic radiation are not.

## 5. What can we learn from studying gravitational waves analogous to photons and EM radiation?

Studying gravitational waves can provide us with a deeper understanding of the universe and the laws of physics. It can also help us to detect and study some of the most extreme and energetic events in the universe, such as the collision of black holes or the formation of galaxies.