DOCSLIB.ORG

The Doppler Effect & Hubble

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Doppler Effect & Hubble The Doppler Effect & Hubble Objectives • Explain the Doppler Effect. • Describe Hubble’s discoveries. • Explain Hubble’s Law. The Doppler Effect • The Doppler Effect is named after Austrian physicist Christian Doppler who proposed it in 1842. The Doppler Effect • The Doppler Effect is the change in frequency and wavelength of a wave that results when the source of the wave is moving relative to an observer. • It is commonly heard when a vehicle sounding a siren or horn approaches, passes, and moves away from an observer. The Doppler Effect • The received frequency is higher (compared to the emitted frequency) as the vehicle approaches, is identical during the instant the vehicle passes by, and is lower as the vehicle moves away. • http://www.colorado.edu/physics/2000/apple ts/doppler2.html The Doppler Effect Explained • When the source of the waves (siren or horn) is moving toward the observer, each successive wave is emitted from a position closer to the observer than the previous wave. • Because it has less distance to travel, each wave takes slightly less time to reach the observer than the previous wave. • So, the time between the arrival of each wave at the observer is reduced, causing an increase in the frequency. • While they are traveling, the distance between wave fronts is reduced; so the waves "bunch together". The Doppler Effect Explained • Conversely, if the source of waves is moving away from the observer, each wave is emitted from a position farther from the observer than the previous wave. • So the arrival time between waves is increased, reducing the frequency. • The distance between waves is increased, so the waves "spread out“ or “stretch”. The Doppler Effect Doppler Simulation • http://astro.unl.edu/classaction/ani mations/light/dopplershift.html Edwin Hubble – 1950’s • American astronomer • Discovered the existence of galaxies other than the Milky Way. • He used Doppler Shift to see that galaxies are moving. Doppler Effect and EMR • The Doppler Effect also applies to electromagnetic radiation. • Just like sound waves, EMR waves increase or decrease in frequency if the object emitting them is moving towards or away from an observer. Redshift and Blueshift • If the object is moving away from observer, the wavelength (of the waves moving back toward the observer) stretches and frequency decreases resulting in REDSHIFT. • If the object is moving towards an observer, the wavelength compresses and the frequency increases resulting in BLUESHIFT. • Remember the spectrum. DOPPLER EFFECT Redshift in Space • If an object in space were moving away from Earth, the EMR waves travelling back to Earth would “stretch” or increase in wavelength and decrease in frequency and “shift” toward the red end of the spectrum. Blueshift • If an object in space were moving toward Earth, the EMR waves moving toward Earth would “compress” or decrease in wavelength and increase in frequency and “shift” toward the blue end of the spectrum. Hydrogen Red Shifted Galaxies • Hubble observed that the light spectra coming from most galaxies was red shifted (observation). • This meant that the galaxies were moving away from Earth (inference). Hubble’s Law • Hubble’s Law: the degree of redshift observed in the light spectra from other galaxies increases in proportion to the galaxies distance from Earth. • OR the greater the degree of redshift, the farther away a galaxy is, and the faster it is moving. • This law would help establish that the known universe is expanding = the BIG BANG THEORY. Redshift vs. Distance Hubble’s Law Red Shifted Galaxies • When we observe the light spectra coming from known galaxies, most are red shifted (observation). • Most galaxies appears to be moving away from us – therefore, the universe is expanding (inference). .
Load more

Recommended publications
  • Glossary Physics (I-Introduction)
    1 Glossary Physics (I-introduction) - Efficiency: The percent of the work put into a machine that is converted into useful work output; = work done / energy used [-]. = eta In machines: The work output of any machine cannot exceed the work input (<=100%); in an ideal machine, where no energy is transformed into heat: work(input) = work(output), =100%. Energy: The property of a system that enables it to do work. Conservation o. E.: Energy cannot be created or destroyed; it may be transformed from one form into another, but the total amount of energy never changes. Equilibrium: The state of an object when not acted upon by a net force or net torque; an object in equilibrium may be at rest or moving at uniform velocity - not accelerating. Mechanical E.: The state of an object or system of objects for which any impressed forces cancels to zero and no acceleration occurs. Dynamic E.: Object is moving without experiencing acceleration. Static E.: Object is at rest.F Force: The influence that can cause an object to be accelerated or retarded; is always in the direction of the net force, hence a vector quantity; the four elementary forces are: Electromagnetic F.: Is an attraction or repulsion G, gravit. const.6.672E-11[Nm2/kg2] between electric charges: d, distance [m] 2 2 2 2 F = 1/(40) (q1q2/d ) [(CC/m )(Nm /C )] = [N] m,M, mass [kg] Gravitational F.: Is a mutual attraction between all masses: q, charge [As] [C] 2 2 2 2 F = GmM/d [Nm /kg kg 1/m ] = [N] 0, dielectric constant Strong F.: (nuclear force) Acts within the nuclei of atoms: 8.854E-12 [C2/Nm2] [F/m] 2 2 2 2 2 F = 1/(40) (e /d ) [(CC/m )(Nm /C )] = [N] , 3.14 [-] Weak F.: Manifests itself in special reactions among elementary e, 1.60210 E-19 [As] [C] particles, such as the reaction that occur in radioactive decay.
    [Show full text]
  • M204; the Doppler Effect
    MISN-0-204 THE DOPPLER EFFECT by Mary Lu Larsen THE DOPPLER EFFECT Towson State University 1. Introduction a. The E®ect . .1 b. Questions to be Answered . 1 2. The Doppler E®ect for Sound a. Wave Source and Receiver Both Stationary . 2 Source Ear b. Wave Source Approaching Stationary Receiver . .2 Stationary c. Receiver Approaching Stationary Source . 4 d. Source and Receiver Approaching Each Other . 5 e. Relative Linear Motion: Three Cases . 6 f. Moving Source Not Equivalent to Moving Receiver . 6 g. The Medium is the Preferred Reference Frame . 7 Moving Ear Away 3. The Doppler E®ect for Light a. Introduction . .7 b. Doppler Broadening of Spectral Lines . 7 c. Receding Galaxies Emit Doppler Shifted Light . 8 4. Limitations of the Results . 9 Moving Ear Toward Acknowledgments. .9 Glossary . 9 Project PHYSNET·Physics Bldg.·Michigan State University·East Lansing, MI 1 2 ID Sheet: MISN-0-204 THIS IS A DEVELOPMENTAL-STAGE PUBLICATION Title: The Doppler E®ect OF PROJECT PHYSNET Author: Mary Lu Larsen, Dept. of Physics, Towson State University The goal of our project is to assist a network of educators and scientists in Version: 4/17/2002 Evaluation: Stage 0 transferring physics from one person to another. We support manuscript processing and distribution, along with communication and information Length: 1 hr; 24 pages systems. We also work with employers to identify basic scienti¯c skills Input Skills: as well as physics topics that are needed in science and technology. A number of our publications are aimed at assisting users in acquiring such 1.
    [Show full text]
  • Throughout the Universe, Galaxies Are Rushing Away from Us – and from Each Other – at Tremendously High Speeds
    Our Universe Began with a Bang Throughout the Universe, galaxies are rushing away from us – and from each other – at tremendously high speeds. This fact tells us that the Universe is expanding over time. Edwin Hubble (after whom the Hubble Space Telescope was named) first measured the expansion in 1929. Observatories of the Carnegie Institution of Washington Edwin Hubble This posed a big question. If we could run the cosmic movie backward in time, would everything in the Universe be crammed together in a blazing fireball – the starting point of Edwin Hubble & Proceedings of The National Academy of Sciences Hubble’s famous diagram showing the the Big Bang? A lot of scientific distance versus velocity of the galaxies he debate and many new theories observed. The farther away the galaxies, the faster they are moving, showing that the followed Hubble’s discovery. Universe is expanding. Among those in the front lines of the debate were physicists Ralph Alpher and Robert Herman. In 1948 they predicted that an afterglow of this fireball should still exist, though at a much lower temperature than at the time of the Big Bang. Here’s why: As the Universe Fun Fact: expands, the waves of heat About radiation from the Big Bang are 1% of the stretched out, and cool from “snow” you see visible energy to infrared and on broadcast TV then to microwave wavelengths. is caused by the Microwaves are just short- cosmic microwave wavelength radio waves, the same background. form of energy used in microwave ovens. The prediction of an afterglow could be tested! Scientists began building instruments to detect this “cosmic microwave background”, or CMB.
    [Show full text]
  • Determining the Motion of Galaxies Using Doppler Redshift
    Determining the Motion of Galaxies Using Doppler Redshift Caitlin M. Matyas The Arts Academy at Benjamin Rush Overview Rationale Objective Strategies Classroom Activities Annotated Bibliography / Resources Standards Appendices Overview The Doppler effect of sound is a method used to determine the relative speeds of an object emitting a sound and an observer. Depending on whether the source and/or observer are moving towards or away from each other, the frequency of the wave will change. This in turn creates a change in pitch perceived by the observer. The relative speeds can easily be calculated using the following formula: � ± �′ = �( ), � ± where f’ represents the shifted frequency, f represents the frequency of the source, v is the speed of sound, vo is the speed of the observer, and vs is the speed of the source. Vo is added if moving towards and subtracted if moving away from the source. vs is added if moving away and subtracted if moving towards the observer. The figures below help to demonstrate the perceived change in frequency. The source is located at the center of the smallest circle. The picture shows waves expanding as they move outwards away from the source, so the earliest emitted waves create the biggest circles. If both the source and observer were stationary, the waves appear to pass at equal periods of time, as seen in figure IA. However, if the source is moving, the frequency appears to change. Figure IB shows what would happen if the source moves towards the right. Although the waves are emitted at a constant frequency, they seem closer together on the right side and farther spaced on the left.
    [Show full text]
  • A New Universe to Discover: a Guide to Careers in Astronomy
    A New Universe to Discover A Guide to Careers in Astronomy Published by The American Astronomical Society What are Astronomy and Astrophysics? Ever since Galileo first turned his new-fangled one-inch “spyglass” on the moon in 1609, the popular image of the astronomer has been someone who peers through a telescope at the night sky. But astronomers virtually never put eye to lens these days. The main source of astronomical data is still photons (particles of light) from space, but the tools used to gather and analyze them are now so sophisticated that it’s no longer necessary (or even possible, in most cases) for a human eye to look through them. But for all the high-tech gadgetry, the 21st-Century astronomer is still trying to answer the same fundamental questions that puzzled Galileo: How does the universe work, and where did it come from? Webster’s dictionary defines “astronomy” as “the science that deals with the material universe beyond the earth’s atmosphere.” This definition is broad enough to include great theoretical physicists like Isaac Newton, Albert Einstein, and Stephen Hawking as well as astronomers like Copernicus, Johanes Kepler, Fred Hoyle, Edwin Hubble, Carl Sagan, Vera Rubin, and Margaret Burbidge. In fact, the words “astronomy” and “astrophysics” are pretty much interchangeable these days. Whatever you call them, astronomers seek the answers to many fascinating and fundamental questions. Among them: *Is there life beyond earth? *How did the sun and the planets form? *How old are the stars? *What exactly are dark matter and dark energy? *How did the Universe begin, and how will it end? Astronomy is a physical (non-biological) science, like physics and chemistry.
    [Show full text]
  • Glossary | Speed Measuring Device Resources 191.94 KB
    GLOSSARY Absorption - The transmitted R.A.D.A.R. beam will, unless otherwise acted upon (absorbed, reflected, or refracted), travel infinitely far. Under practical circumstances, the beam may be partially absorbed by natural and man-made substances. Vegetation such as trees, grass, and bushes will absorb R.A.D.A.R. energy. Freshly turned earth, such as that in a freshly plowed field, will also absorb R.A.D.A.R. Plastics of certain types and foam products will absorb R.A.D.A.R., as makers of "stealth" automotive accessories have discovered. Absorption of R.A.D.A.R. will not result in any inaccuracies in the R.A.D.A.R. readings. It will reduce the strength of the returned signal, and the operational range of the device depending upon the circumstances. Absolute speed limits - Holds that a given speed limit is in force, regardless of environment conditions, i.e., 35 mph or 50 mph. Accuracy - When used in conjunction with R.A.D.A.R. devices means the degree to which the R.A.D.A.R. device measures and displays the correct speed of a target vehicle that it is tracking. Ambient interference - The conducted and/or radiated electromagnetic interference and/or mechanical motion interference at a specific location and at a time which would be detrimental to proper R.A.D.A.R. performance. Antenna horn - The antenna horn is that portion of the R.A.D.A.R. device that shapes and directs the microwave energy (beam). The antenna horn also "catches" the returning microwave energy and directs it to the R.A.D.A.R.
    [Show full text]
  • Doppler Effect
    Physical Science Workshop: Astronomy Applications of Light & Color 1 Activity: Doppler Effect Background: • The Doppler effect causes a train whistle, car, or airplane to sound higher when it is moving towards you, and lower when it is moving away from you. From: http://www.physics.purdue.edu/astr263l/inlabs/doppler.html • For sound: high pitch = high frequency = short wavelength • Light is also a wave, and affected by the Doppler effect o longer wavelengths (lower frequencies) of light appear redder o The spectrum of a star moving towards you will appear blueshifted (shorter wavelengths / higher frequencies) o The spectrum of a star moving away from you will appear redshifted (longer wavelengths / lower frequencies) From: http://www.astrosociety.org/education/publications/tnl/55/astrocappella3.html Lab Materials: • computer with internet access S. Sallmen Activity: Doppler Effect Physical Science Workshop: Astronomy Applications of Light & Color 2 Activity: Doppler Basics: • Go to: http://www.fearofphysics.com/Sound/dopwhy2.html 1. Watch the waves reaching your ear if: • the source moves towards your ear at 100 meters / second • the source moves away from your ear at 100 meters / second a. In which case is the frequency of sound higher? b. In which case is the wavelength of the sound waves longest? c. If these were light waves, in which case would the light reaching your eye be redder? d. If these were light waves, in which case would the light reaching your eye be bluer? 2. Watch the waves reaching your ear if: • the source moves away from your ear at 100 meters / second • the source moves away from your ear at 200 meters / second a.
    [Show full text]
  • Gravity Tests with Radio Pulsars
    universe Review Gravity Tests with Radio Pulsars Norbert Wex 1,* and Michael Kramer 1,2 1 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany; [email protected] 2 Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL, UK * Correspondence: [email protected] Received: 19 August 2020; Accepted: 17 September 2020; Published: 22 September 2020 Abstract: The discovery of the first binary pulsar in 1974 has opened up a completely new field of experimental gravity. In numerous important ways, pulsars have taken precision gravity tests quantitatively and qualitatively beyond the weak-field slow-motion regime of the Solar System. Apart from the first verification of the existence of gravitational waves, binary pulsars for the first time gave us the possibility to study the dynamics of strongly self-gravitating bodies with high precision. To date there are several radio pulsars known which can be utilized for precision tests of gravity. Depending on their orbital properties and the nature of their companion, these pulsars probe various different predictions of general relativity and its alternatives in the mildly relativistic strong-field regime. In many aspects, pulsar tests are complementary to other present and upcoming gravity experiments, like gravitational-wave observatories or the Event Horizon Telescope. This review gives an introduction to gravity tests with radio pulsars and its theoretical foundations, highlights some of the most important results, and gives a brief outlook into the future of this important field of experimental gravity. Keywords: gravity; general relativity; pulsars 1.
    [Show full text]
  • Edwin Hubble (1889-1953) Measured Distance to Andromeda Galaxy (M31) • Noticed Individual Bright Stars in Andromeda
    The Resolution: Edwin Hubble (1889-1953) Measured Distance to Andromeda Galaxy (M31) • Noticed individual bright stars in Andromeda • Calculated the distance using the Period-Luminosity Relation for Cepheid Variable Stars The Resolution: Edwin Hubble (1889-1953) Measured Distance to Andromeda Galaxy (M31) • Noticed individual bright stars in Andromeda • Calculated the distance using the Period-Luminosity Relation for Cepheid Variable Stars 1. MEASURED magnitude & Period The Resolution: Edwin Hubble (1889-1953) Measured Distance to Andromeda Galaxy (M31) • Noticed individual bright stars in Andromeda • Calculated the distance using the Period-Luminosity Relation for Cepheid Variable Stars 1. MEASURED magnitude & Period 2. CALCULATED Luminosity The Resolution: Edwin Hubble (1889-1953) Measured Distance to Andromeda Galaxy (M31) • Noticed individual bright stars in Andromeda • Calculated the distance using the Period-Luminosity Relation for Cepheid Variable Stars 1. MEASURED magnitude & Period 2. CALCULATED Luminosity 3. CALCULATED Distance The Resolution: Edwin Hubble (1889-1953) Measured Distance to Andromeda Galaxy (M31) • Noticed individual bright stars in Andromeda • Calculated the distance using the Period-Luminosity Relation for Cepheid Variable Stars 1. MEASURED magnitude & Period 2. CALCULATED Luminosity 3. CALCULATED Distance • Result was MUCH farther than expected... • (2.3 Million Ly - well beyond Milky Way) Henrietta Leavitt & Period-Luminosity Relation Cepheid Variables: Bright stars whose Luminosity (energy output) varies every
    [Show full text]
  • Lecture 21: the Doppler Effect
    Matthew Schwartz Lecture 21: The Doppler effect 1 Moving sources We’d like to understand what happens when waves are produced from a moving source. Let’s say we have a source emitting sound with the frequency ν. In this case, the maxima of the 1 amplitude of the wave produced occur at intervals of the period T = ν . If the source is at rest, an observer would receive these maxima spaced by T . If we draw the waves, the maxima are separated by a wavelength λ = Tcs, with cs the speed of sound. Now, say the source is moving at velocity vs. After the source emits one maximum, it moves a distance vsT towards the observer before it emits the next maximum. Thus the two successive maxima will be closer than λ apart. In fact, they will be λahead = (cs vs)T apart. The second maximum will arrive in less than T from the first blip. It will arrive with− period λahead cs vs Tahead = = − T (1) cs cs The frequency of the blips/maxima directly ahead of the siren is thus 1 cs 1 cs νahead = = = ν . (2) T cs vs T cs vs ahead − − In other words, if the source is traveling directly towards us, the frequency we hear is shifted c upwards by a factor of s . cs − vs We can do a similar calculation for the case in which the source is traveling directly away from us with velocity v. In this case, in between pulses, the source travels a distance T and the old pulse travels outwards by a distance csT .
    [Show full text]
  • The Universe.Pdf
    Standard 1: Students will o understand the scientific Terms to know evidence that supports theories o Big Bang Theory that explain how the universe o Doppler Effect and the solar system developed. o Redshift They will compare Earth to other o Universe objects in the solar system. Standard 1, Objective 1: Describe both the big bang theory of universe formation and the nebular theory of solar system formation and evidence supporting them. Lesson Objectives • Explain the evidence for an expanding universe. • Describe the formation of the universe according to the Big Bang Theory. Introduction The study of the universe is called cosmology. Cosmologists study the structure and changes in the present universe. The universe contains all of the star systems, galaxies, gas and dust, plus all the matter and energy that exist. The universe also includes all of space and time. Evolution of Human Understanding of the Universe What did the ancient Greeks recognize as the universe? In their model, the universe contained Earth at the center, the Sun, the Moon, five planets, and a sphere to which all the stars were attached. This idea held for many centuries until Galileo's telescope allowed people to recognize that Earth is not the center of the universe. They also found out that there are many more stars than were visible to the naked eye. All of those stars were in the Milky Way Galaxy. 13 Timeline of cosmological theories 4th century BCE — Aristotle proposes a Geocentric (Earth-centered) universe in which the Earth is stationary and the cosmos (or universe) revolves around the Earth.
    [Show full text]
  • Dopper Effect Lesson Plan
    DOPPER EFFECT LESSON PLAN Description Through experiments students will see and hear the Doppler effect, and apply their new knowledge to the hydrogen emission spectrum. Curriculum Fit Grade 9, Unit E: Space Exploration Specific Learner Expectations 1. Describe and apply techniques for determining the position and motion of objects in space, including: describing in general terms how parallax and the Doppler effect are used to estimate distances of objects in space and to determine their motion Key Terms • Doppler effect: an increase (or decrease) in the frequency of sound, light, or other waves as the source and observer move toward (or away from) each other. The effect causes the sudden change in pitch noticeable in a passing siren, as well as the redshift seen by astronomers • Redshift: When light or any waves on the electromagnetic spectrum are lengthened as the source of those waves moves away from us. It is called a ‘redshift’ in the light as the wavelength shifts toward the red side (longer wavelengths) of the electromagnetic spectrum • Blueshift: When light or any waves on the electromagnetic spectrum are shortened (compressed) as the source of these waves moves toward us. It is called a ‘blueshift’ in the light as the wavelength shifts toward the blue side (shorter wavelengths) of the electromagnetic spectrum • Exoplanet: A planet outside of our solar system • Emission Spectrum: A spectrum of the electromagnetic radiation emitted by a source Introduction Watch the “Doppler Effect” video as an introduction to this lesson. Have you heard the wail of an emergency vehicle’s siren as the vehicle races toward you, and then experienced the sudden drop in pitch as it passes you? This change can be explained by the Doppler effect.
    [Show full text]