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List of cosmic microwave background experiments

List of cosmic microwave background experiments is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand List of cosmic microwave background experiments rather than just read about it. In short: This list is a compilation of experiments measuring the cosmic microwave background (CMB) radiation anisotropies and polarization since the first detection of the CMB by Penzias and Wilson in 1964. There have been a variety of experiments to measure the CMB anisotropies and polarization since its first observation in 1964 by Penzias and Wilson.

Key takeaways

List of cosmic microwave background experiments belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect List of cosmic microwave background experiments to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of List of cosmic microwave background experiments from memory before moving on to harder problems.

Reference excerpt

This list is a compilation of experiments measuring the cosmic microwave background (CMB) radiation anisotropies and polarization since the first detection of the CMB by Penzias and Wilson in 1964. There have been a variety of experiments to measure the CMB anisotropies and polarization since its first observation in 1964 by Penzias and Wilson. These include a mix of ground-, balloon- and space-based receivers. Some notable experiments in the list are COBE, which first detected the temperature anisotropies of the CMB, and showed that it had a black body spectrum; DASI, which first detected the polarization signal from the CMB; CBI, which made high-resolution observations and obtained the first E-mode polarization spectrum; WMAP; and the Planck spacecraft, which has produced the highest resolution all-sky map to-date of both the temperature anisotropies and polarization signals. Current scientific goals for CMB observation include precise measurement of gravitational lensing, which can constrain the mass of the neutrino; and measurement of B-mode polarization as possible evidence for cosmic inflation. The design of cosmic microwave background experiments is a very challenging task. The greatest problems are the receivers, the telescope optics and the atmosphere. Many improved microwave amplifier technologies have been designed for microwave background applications. Some technologies used are HEMT, MMIC, SIS and bolometers. Experiments generally use elaborate cryogenic systems to keep the amplifiers cool. Often, experiments are interferometers which only measure the spatial fluctuations in signals on the sky, and are insensitive to the average 2.7 K background.

Another problem is the 1/f noise intrinsic to all detectors. Usually the experimental scan strategy is designed to minimize the effect of such noise. To minimize side lobes, microwave optics usually utilize elaborate lenses and feed horns. Finally, in ground-based (and, to an extent, balloon-based) instruments, water and oxygen in the atmosphere emit and absorb microwave radiation. Even at frequencies where the atmospheric transmission is high, atmospheric emission contributes photon noise that limits the sensitivity of an experiment. CMB research therefore uses of air- and space-borne experiments, as well as dry, high altitude locations such as the Chilean Andes and the South Pole.

Cosmic microwave background experiments

The list below consists of a partial list of past, current and planned CMB experiments. The name, start and end years of each experiment are given, followed by the basis of the experiment—whether space, balloon or ground based—and the location where appropriate. The frequency and amplifier technologies used are given, as is the main targets of the experiments.

References

Further reading NASA, 2015, "Hosted Data on LAMBDA: CMB Experiments," see [1], accessed 27 March 2015.

Illustrations

Worked examples

Example 1 — a first encounter with List of cosmic microwave background experiments

Start with the simplest possible case. Write down what List of cosmic microwave background experiments claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to List of cosmic microwave background experiments before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about List of cosmic microwave background experiments ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of List of cosmic microwave background experiments

In research: List of cosmic microwave background experiments appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses List of cosmic microwave background experiments in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: List of cosmic microwave background experiments is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cosmic microwave background experiments, so understanding it makes those chapters shorter.
In everyday life: Look for List of cosmic microwave background experiments outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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Frequently asked questions

What is List of cosmic microwave background experiments in simple terms?

Why does List of cosmic microwave background experiments matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

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Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

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