Here is a good read on stealth: It's relatively small, under kg and can be retrofit to existing aircraft - Kirk can steal one! Or other series where they "install the cloaking device"? If it was this gravitational field generator inside the ship what would happen to the ship?
The intricate cosmic web of dark matter and galaxies spanning more than one billion light years. The pink-yellow plumes seen with gravitational lensing show us where the dark matter is.
What is Gravitational Lensing? Cosmology is the branch of astronomy which asks the biggest questions of all — what is the Universe made of?
How did it form?
How old is it? What will happen to our Universe in the distant future?
How and why do the biggest structures in the Universe come about? Humanity has been asking questions like this for millennia, but it is only in the past century that modern telescopes have been powerful enough to start providing meaningful answers.
Our understanding of the Universe today can be summarised in one simple pie chart: Mass-energy equivalence means that we can equate the two; mass is just a measure of the internal energy content of an object.
The other two pieces of the pie are dark matter and dark energyand together they make up almost all of the known Universe. It might seem strange to claim that most of the Universe is invisible and unknown to us, but the evidence for these mysterious entities is compelling.
To learn more about dark matter and dark energy, follow the links on the left hand side. When astronomers refer to lensing, they are talking about an effect called gravitational lensing. Normal lenses such as the ones in a magnifying glass or a pair of spectacles work by bending light rays that pass through them in a process known as refraction, in order to focus the light somewhere such as in your eye.
The gravitational field of a massive object will extend far into space, and cause light rays passing close to that object and thus through its gravitational field to be bent and refocused somewhere else. The more massive the object, the stronger its gravitational field and hence the greater the bending of light rays - just like using denser materials to make optical lenses results in a greater amount of refraction.
Even the mass of our own bodies will lens light passing near us a tiny bit, although the effect is too small to ever measure. So what are the effects of lensing? The kind of lensing that cosmologists are interested in is apparent only on the largest scales — by looking at galaxies and clusters of galaxies.
When astronomers take a telescope image of a part of the night sky, we can see many galaxies on that image. However, in between the Earth and those galaxies is a mysterious entity called dark matter. This means that light rays coming towards us from distant galaxies will pass through the gravitational field of dark matter and hence will be bent by the lensing effect.
For example, a large galaxy cluster will contain a very great amount of dark matter, which exists within and around the galaxies that make up that cluster. Light coming from more distant galaxies that passes close to a cluster may be distorted — lensed — by its mass.
It is the dark matter in the cluster that does almost all of the lensing as it outweighs regular matter by a factor of six or so.
The effects can be very strong and very strange; the images of the distant, lensed galaxies are stretched and pulled into arcs as the light passes close to the foreground cluster. This can be seen in the image below of the famous Abell cluster.
The real galaxies are not this shape — they are usually elliptical or spiral shaped — they just appear this way because of lensing. The net effect of this is a distortion to the shape of the galaxy image, which can in some cases be very severe.In light of the surge in popularity of electromagnetic cloaking devices, we consider whether it is possible to use general relativity to cloak a volume of spacetime through gravitational lensing.
Thus, if gravitational lensing were used as a mechanism for cloaking, the internal region would be causally isolated from the external spacetime. Gravitational lensing, which is the de°ection of light by gravitational ﬂelds and the resulting eﬁect on images, is widely useful in cosmology and, at the same time, .
1 Introduction to lensing 1 These scripts aim at helping the students of the course on Gravitational Lensing to better understand the arguments discussed in the class. Their goal is to give an overview on gravitational lensing and on its wide phenomenology. Definition Let cylinder be defined in Euclidian space where is the cloaking device.
The cylinder is time sliced for discretization and permeability is equal to permittivity with both equal to, the virtual Euclidian gravitational constant.
Using Gravitational Lensing to Measure Age and Size of Universe. Researchers are already aware of more than twenty other astronomical systems suitable for analysis with gravitational lensing.