One implication of the theory is that vigorously whirling large masses around will generate gravitational waves, and as gravity is described as the warping and curvature of spacetime, these gravitational waves are simply ripples in the fabric of space.

This ability to look back in time is based on the fact that even light has a speed limit. It bowls along at 186,000 miles per second. So if you look at a star that is 30 light years away, that is what it looked like 30 years ago. The same applies to stars that are millions of light years away.

It shows “ripples” in the Microwave Background radiation: the photons of light emitted at the epoch when the Universe became cool enough for neutral hydrogen gas to form, allowing the light to stream freely towards us – rather like a fog clearing.

How does the theory of inflation explain the near-uniformity of the cosmic microwave background? Prior to rapid inflation, all regions of space were close enough to bounce radiation back-and-forth and reach the same temperature.

Tests of Big Bang: The CMB. The Big Bang theory predicts that the early universe was a very hot place and that as it expands, the gas within it cools. Thus the universe should be filled with radiation that is literally the remnant heat left over from the Big Bang, called the “cosmic microwave background”, or CMB.

The reason the CMB is still around is because the Big Bang, which itself came about at the end of inflation, happened over an incredibly large region of space, a region that’s at least as large as where we observe the CMB to still be.

The CMB has the spectrum of a blackbody. A blackbody spectrum is produced by an isothermal, opaque and non-reflecting object. A simple gedanken experiment shows that the spectrum emitted by a blackbody can only depend on its temperature T.

Originally, CMB photons had much shorter wavelengths with high associated energy, corresponding to a temperature of about 3,000 K (nearly 5,000° F). As the universe expanded, the light was stretched into longer and less energetic wavelengths. This is why CMB is so cold now.

The cosmic microwave background (CMB) is radiation left over from the Big Bang. Yes. After another few trillion years, the current cosmic microwave background will have redshifted into insignificance and will no longer be detectable.

Created shortly after the universe came into being in the Big Bang, the CMB represents the earliest radiation that can be detected. Astronomers have likened the CMB to seeing sunlight penetrating an overcast sky.

13.8 billion light years

However, because it is so cold, the light which was emitted by the glowing Universe now has a much longer wavelength than we can see with our eyes. The CMB is brightest at a wavelength of around 2 mm, which is around 4000 times longer than the wavelength of the visible light we see with our eyes.

Bottom line: New observations of the oldest light in the universe indicate that the cosmos is 13.77 billion years old, and help resolve inconsistencies with other previous estimates.

300,000 years old

This is because the COBE instrument had “blurry vision” (poor resolution) and could only measure large patches of the sky. We needed instruments with “sharper vision.” The most detailed measurements of the CMB have been obtained by two satellites launched more recently than COBE.

The CMB patterns do indeed change over time, although statistically they remain the same, and although it will not be noticeable on human timescales.

The CMB is faint cosmic background radiation filling all space. It is an important source of data on the early universe because it is the oldest electromagnetic radiation in the universe, dating to the epoch of recombination. CMB is landmark evidence of the Big Bang origin of the universe.

The CMB was created at every point in the universe and thus is visible from all points in the universe. This light was emitted randomly in all directions and is the CMB we know and love today (stretched due to cosmic expansion. This same scattering, adsorption and emission dance occurs in the sun.

2.725 Kelvin

CMB ANISOTROPY. The temperature anisotropies of the CMB detected by COBE are believed to result from inhomogeneities in the distribution of matter at the epoch of recombination. On large (super-horizon) scales, the anisotropies seen in the CMB are produced by the Sachs-Wolfe effect (Sachs & Wolfe, 1967).

A map of the sky at microwave frequencies, showing that the CMB is almost completely the same in all directions.

Our universe would have been microscopic in size prior to inflation, and small differences in the density of matter would also be stretched by inflation. So Inflation Theory explains why the CMB is so nearly uniform, and also how galaxies, stars, planets and people came to be!

Cosmologists speculate about the new physics needed to produce the primordial fluctuations that formed galaxies. Two popular ideas are: Inflation. Topological Defects.

Gravity could work differently across the Universe too. There could be planets out there, where gravity would be strongest on the objects with smaller masses. If the Universe isn’t uniform, we could be wrong about how far the Andromeda galaxy is from us, and how soon it will collide with our galaxy, the Milky Way.

Our View of the Universe. Since the expansion of space occurs evenly at every point in the universe, galaxies are separating from each other at about the same pace, giving the universe a nearly uniform density and structure. As a result, the universe appears smooth at large distance scales.