astronomy

Quasars, Redshifts and Controversies

Quasars, Redshifts and Controversies is a astronomy 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 Quasars, Redshifts and Controversies rather than just read about it. In short: Quasars, Redshifts and Controversies is a 1987 book by Halton Arp, an astronomer famous for his Atlas of Peculiar Galaxies (1966). Arp argued that many quasars with otherwise high redshift are somehow linked to close objects such as nearby galaxies.

Key takeaways

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

Reference excerpt

Quasars, Redshifts and Controversies is a 1987 book by Halton Arp, an astronomer famous for his Atlas of Peculiar Galaxies (1966). Arp argued that many quasars with otherwise high redshift are somehow linked to close objects such as nearby galaxies. Arp also argued that some galaxies showed unusual redshifts, and that redshifts themselves could be quantized. These are controversial views which do not accord with the standard model of physical cosmology. It also contradicts the accepted model that quasars are bright nuclei of very distant galaxies. Most astronomers reject Arp's interpretation of the data since the anomalous observations could be explained by perspective effects. Reportedly, some of Arp's calculations seem to be simply "bad mathematics". Arp asserted that many questions he posed to the scientific establishment are still unanswered and that his requests for more observation time had been systematically rejected. Halton Arp's proposal was an idea based on analyses done before the sky surveys increased the number of measured redshifts by several orders of magnitude. The idea was that the cosmological redshift might be showing evidence of periodicity which would be difficult to explain in a Hubble's law universe that had the feature of continuous expansion. However, most astronomers agree that the analysis suffers from poor methodology and small number statistics. Halton Arp continued to report the existence of apparently connected objects with very different redshifts. Arp has interpreted these connections to mean that these objects are in fact physically connected. He further hypothesized that the higher redshift objects are ejected from the lower redshift objects - which are usually active galactic nuclei (AGN)- and that the large observed redshifts of these "ejected" objects is dominated by a non-cosmological (intrinsic) component. The rest of the community regards these as chance alignments and Arp's hypothesis has very few supporters. The book has been translated into Italian and Spanish, as of 1998. His work is updated in his last book, Catalogue of Discordant Redshift Associations, C. Roy Keys Inc. (February, 2003), ISBN 978-0968368992.

Worked examples

Example 1 — a first encounter with Quasars, Redshifts and Controversies

Start with the simplest possible case. Write down what Quasars, Redshifts and Controversies claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, 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 Quasars, Redshifts and Controversies 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 Quasars, Redshifts and Controversies 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 Quasars, Redshifts and Controversies

In research: Quasars, Redshifts and Controversies appears in astronomy 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 Quasars, Redshifts and Controversies 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: Quasars, Redshifts and Controversies is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1987 non-fiction books, Astronomy books, so understanding it makes those chapters shorter.
In everyday life: Look for Quasars, Redshifts and Controversies 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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How to study Quasars, Redshifts and Controversies in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Quasars, Redshifts and Controversies means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Quasars, Redshifts and Controversies out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Quasars, Redshifts and Controversies in simple terms?

Why does Quasars, Redshifts and Controversies matter?

Because it connects several astronomy 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.

How should I study Quasars, Redshifts and Controversies?

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.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Quasars, Redshifts and Controversies.