The tesseract is the four dimensional analogue of the cube. The cube is to the tesseract what the square is to the cube. The cube has a surface composed of six faces (squares). A tesseract has a hypersurface composed of eight cells (cubes) and is also called an octachoron or 8-cell. You can also call a tesseract a hypercube. The prefix hyper- simply means it has more than three dimensions. You can also have 5D hypercube. Of course we cannot physically construct a tesseract in four dimensions, but we can create a projection in two or three dimensions,
The easiest way to draw a tesseract is to connect the vertices of two cubes. Compare it to the drawing of a cube, where you connect the vertices of two squares. Remember that you are only looking at a lower dimensional “shadow” of a tesseract. All cubes in the tesseract are the same size. The cube in the centre appears smaller because it is further away in four dimensions.
Zooids can only survive when in contact with other zooids. Each has its individual personality, but collectively they exist as a single being with a shared goal of survival, the man o’ war.
The Portuguese man o’ war lives at the surface of the ocean. The gas-filled bladder floats at the surface and the remainder is submerged. each type of zooid has a specific role and is specialised within the man o’ war structure. Some make up the bladder whilst others form poisonous tentacles that capture and kill prey for the benefit of the whole colony . The tentacles can reach 50 metres in length. The man o’ war floats on the winds, currents, and tides, it cannot move itself.
The photography above is made by Aaron Ansarov. Aaron wanted to portray the beauty of the organism by capturing the colours in artistic arrangements. The results look strangely familiar.. Aaron used beached man ’ o wars for the photography. After the photographs were made, the creatures were released were they were found.
In a vacuum light of any wavelength will travel at a fixed speed, c. But light takes longer to travel through a different medium (such as glass or water) because it interacts with atoms in the medium, getting absorbed and re-emitted repeatedly. Light of shorter wavelengths (indigo) interacts stronger, so it will take longer to pass through a medium than light of longer wavelengths (red).
As white light enters a medium (in this case, the prism), each of its composing wavelengths will propagate at a different speed in the new medium, and this change in speed is what bends the path in which light is travelling. This is the phenomenon we call refraction. The ratio between the speed of light in vacuum and the speed of light in a medium is what we call index of refraction, and this value is specific for a given wavelength and medium.
It is important to realise that the speed of light is always constant, but only the interaction in the medium causes the light to take longer to travel through it. To say light travels slower is inaccurate.. between absorption and re-emission from atoms in the medium light still travels at the speed of light..