Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 34: Q21CQ (page 1237)

Lacking direct evidence of WIMPs as dark matter, why must we eliminate all other possible explanations based on the known forms of matter before we invoke their existence?

Short Answer

Expert verified

Because we must not complicate our theory by introducing additional particles if a better explanation can be found using existing forms of matter.

Step by step solution

01

Definition of WIMPs.

A WIMP has no precise description, but it is a new elementary particle that interacts with gravity and any other force (or forces) that is as weak as or weaker than the weak nuclear force, but non-vanishing in strength.

02

Explaining Occam's razor.

Occam's razor is a problem-solving principle that states that if two theories provide equally precise explanations and predictions, the one with fewer assumptions is the "right" one.

With this in mind, if dark matter can be explained using existing particles, Occam's razor suggests that there is no need to include new particles, as this would complicate our hypothesis unnecessarily.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

The core of a star collapses during a supernova, forming a neutron star. Angular momentum of the core is conserved, and so the neutron star spins rapidly. If the initial core radius is\({\rm{5 \times 1}}{{\rm{0}}^{\rm{5}}}{\rm{ km}}\)and it collapses to\({\rm{10}}{\rm{.0 km}}\), find the neutron star’s angular velocity in revolutions per second, given the core’s angular velocity was originally\({\rm{1}}\)revolution per\({\rm{30}}\)days.

If the dark matter in the Milky Way were composed entirely of MACHOs (evidence shows it is not), approximately how many would there have to be? Assume the average mass of a MACHO is\({\rm{1/1000}}\)that of the Sun, and that dark matter has a mass\({\rm{10}}\)times that of the luminous Milky Way galaxy with its\({\rm{1}}{{\rm{0}}^{{\rm{11}}}}\)stars of average mass\({\rm{1}}{\rm{.5}}\)times the Sun’s mass.

If the cosmic microwave background radiation (CMBR) is the remnant of the Big Bang’s fireball, we expect to see hot and cold regions in it. What are two causes of these wrinkles in the CMBR? Are the observed temperature variations greater or less than originally expected?

The critical mass density needed to just halt the expansion of the universe is approximately\({\rm{1}}{{\rm{0}}^{{\rm{ - 26}}}}{\rm{ kg/}}{{\rm{m}}^{\rm{3}}}\). (a) Convert this to\({\rm{eV/}}{{\rm{c}}^{\rm{2}}} \cdot {{\rm{m}}^{\rm{3}}}\). (b) Find the number of neutrinos per cubic meter needed to close the universe if their average mass is\({\rm{7 eV/}}{{\rm{c}}^{\rm{2}}}\)and they have negligible kinetic energies.

Black holes with masses smaller than those formed in supernovas may have been created in the Big Bang. Calculate the radius of one that has a mass equal to the Earth’s.
See all solutions

Recommended explanations on Physics Textbooks

Solid State Physics

Read Explanation

Rotational Dynamics

Read Explanation

Linear Momentum

Read Explanation

Quantum Physics

Read Explanation

Modern Physics

Read Explanation

Electricity and Magnetism

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free