Left click hyperlink filename to play sound or movie. Right click to copy file to your own computer.
Sound files are .wav and Movies are .mov (Quicktime) or .mpg (mpeg). Remember, small "laptop" speakers miss the deeper frequencies, so it is best to play the sounds over at least the larger type of computer speakers.

First, a small selection of the most important sound and movie files.

Evolving Sounds: the First 100 Million Years

The first million years. The sound files take the first million years of cosmic sound and compress it into 10 seconds. The first allows the loudness to vary (V) correctly (it increases with time), while the second holds it constant (C). Two Quicktime movies show slightly different versions of the changing sound spectrum, along with the changing sound waveform and sky color. (from slide 107).

The first 100 million years. These sound files take the first 100 million years of cosmic sound and compresses the time "exponentially" so that the first 2 seconds span 100 to 1000 years; the next two seconds span 1000 to 10,000 years; and so on, with 2 seconds for each factor of 10 increase in time, all the way up to 100 million years (total of 14 seconds). The true volume increase is too great to render correctly. Instead, the first version fakes an increase to illustrate reality (Vfake), while the second keeps the volume constant (C). Two Quicktime movies show slightly different versions of the changing sound spectrum, along with the changing sound waveform and sky color. (from slide 109).

Raw/Pure Sounds: Measuring the Universe

The raw sound constructed from the observed angular power spectrum of the microwave background. This is the fundamental observational basis for Big Bang Acoustics. In practice, a number of distortions are present in these raw sounds, which have been removed using a sophisticated program (CMBFAST) for all but the next two sounds. (from slide 43).

The raw sounds from different types of Universe, calculated using CMBFAST. The first plays the sound of three Universes of different density -- the densest Universe has the deepest voice, while the middle sound matches the sound of our real Universe. The second plays the sound of three Universes with different atomic content : 2%, 4% and 8% of the total content are atoms (the rest is dark matter and dark energy). These are more difficult to tell apart, but the middle one (4%) matches the raw sound of our real Universe. (from slide 58 and slide 61).).

Comparison of the "Raw" sound (calculated from the sound spectrum of the microwave background) and the "Pure" sound (calculated using CMBFAST). The pure sound removes many distortions which find their way into the microwave background and is a much closer match to the true acoustic sound. In this clip, the raw and pure sounds alternate, with the raw sound first. [For those in the know, the raw sound comes from C(l) while the pure sound comes from P(k).] (from slide 71).

Cosmic Music: Replacing the Harmonics.

The first 400,000 years compressed to 10 seconds with varying volume. The s_ version is the pure (undistorted) sound. This, amazingly, includes a number of broad harmonics, suggesting the young Universe was behaving like a musical instrument. However, because the harmonics are broad, they dont sound like pure tones. To help bring out the "musical nature" of the sound, one can replace each broad harmonic with a pure tone of the same pitch and loudness. h_ gives this Musical version. The hs_ version adds these two together, to help our ear hear the harmonics while keeping its more authentic "rough" form.

The next two sounds repeat the h_ Musical version but with the downward slide removed (by fixing the 1st harmonic to the A below concert A) This now allows our ears to hear the subtly changing chord. The NF3mVD version has the exact (microtonal) pitches while the NF3nVD version has the pitches forced to our tempered scale, which gives the discrete changes as the true tones wander between our tempered notes. (From Slide 88 which shows the changing harmonics graphically & musically)

Essentially exactly the same as the versions above, but for the first 10 million years played with exponential time (2 seconds per factor of 10 in time) and constant volume. There is one additional version (NF1nCD) which places all harmonics into a single octave, giving a compact chord. (from slide 83 and slide 85).).

Sounds From The Newborn Universe

This selection includes essentially all sounds and movies from the main narrative ("3b: Full Presentation" found on my homepage). There are 16 themes spanning 168 slides, which is how the files are organized here, with the slide number indicated. A small GIF image of the slide is also available, as well as a few selected slides which don't have associated sounds or movies.

1: Introduction & Overview

The sound from the first million years after the big bang, compressed to 10 seconds (1 second per 100,000 years), and with the volume held constant.

2: The First Million Years

3: The Microwave Background

4: Cosmic Acoustics

The sounds from a Clarinet and Flute playing the same note. The difference in sound is visible in the two sound spectra. (Taken from Joe Wolfe's work at UNSW).

5: The CMB Sound Spectrum

The raw sound constructed from the observed angular power spectrum of the microwave background.

6: Origins of Cosmic Sound

7: Using Sound to Measure the Universe

A sequence of raw sounds for Universes spanning a range of density, from 50% of "closure" density, to 150%. The denser Universes have the deeper voice. The true Universe seems to have exactly the closure density, ie 100%. The power spectra were calculated using CMBFAST -- the computer simulation of the early universe.

Two sequence of raw sounds for Universes spanning a range of atomic content. The first sequence spans the range 10% to 90% of the "closure" density in atoms. The second spans the range 2% to 10%. The true Universe has 4% atomic content.

8: Removing Distortion: From C(l) to P(k)

Comparison of the "Raw" sound (taken directly from the power spectrum of the microwave background) and the "Pure" sound (calculated using CMBFAST). The pure sound has now removed many distortions which find their way into the microwave background. It is a much closer match to the true acoustic sound. In this clip, the raw and pure sounds alternate, with the raw sound first.

Comparison of pure frequency and spread of frequencies, centered on 200 Hz; 600 Hz and 1000 Hz. This shows how a range of frequencies makes an indistinct note. Similarly, the cosmic harmonics don't sound like notes to our ears because they too contain a spread of frequencies.

9: Evolving Sounds

Pure cosmic sounds from three different times: 400,000 years; 50,000 years; 1000 years. Earlier times have higher pitches. (The z values in the names signify the redshift corresponding to the time, ie by what factor the Universe was smaller.)

Quicktime movie showing the changing sound spectrum across the first 400,000 years, together with the changing sound waveform and sky color. Bars at the top allow you to follow the changing cosmic size and time.

Quicktime movies of the same time period (first 400,000 years) but showing just the sound spectrum, with a simple bar crossing to track time. bar_linF uses frequency, while bar_linW uses wavelength to plot the sound spectrum. The accompanying sounds are also given as a separate files. lin_C plays the sound a constant volume, while lin_V follows the true change in volume (the volume increases as time passes).

10: Fun with Chord Analysis

Compares Raw, Pure, and Musical versions of the sound from about 300,000 years. The Raw and Pure versions were played in slide 71. The Musical version has replace all the broad harmonics with single tones of the appropriate frequency and loudness. This renders the sound suitable for our ears, since we don't discern notes from broad harmonics (see slide 72). The Musical version is essentially a chord with a number of interesting intervals in it, including a major third and a minor third.

Three versions of the first 10 million years of sound, played with an exponential time such that 2 seconds elapse for the intervals: 100 to 1000 years, 1000 to 10,000 years, 10,000 to 100,000 years, etc. In all cases the volume has been held fixed (otherwise the latter times would drown out the earlier times). s_.wav gives the "Pure" sound, with distortions removed (using CMBFAST) but keeping the broad harmonics. h_.wav gives the Musical sound, where the first 8 harmonic peaks have been replaced by pure tones. hs_.wav has added these together so that one hears both the natural sound as well as the hidden harmonics. Related versions, but with the downward slide removed are given in slide 85.

Three Musical versions (ie harmonic peaks replaced by pure tones) of the period 10,000 to 3 million years, played with exponential time as in slide 83. In these versions the downward slide in pitch has been removed (by anchoring the first harmonic to 220 Hz), allowing our ear to hear the subtle changes in the chord. NF3mCD gives the "microtonal" version, which means that the true frequencies relative to the lowest harmonic are reproduced exactly. In this case, tones which are not on our musical scale are included. The NF3nCD version forces all tones to be played at the pitch of the closest note in our musical (tempered) scale. These notes change abruptly as the slowly drifting harmonics shift closer or further from specific tempered notes. The NF1nCD version also uses the tempered scale, but puts all harmonics into a single octave, making a compact chord. In all these versions, the overall volume has been set to a constant, though the loudness of the individual harmonics has been allowed to vary appropriately (eg, for reasons explained in the Presentation, the even numbered harmonics gradually get weaker after about 200,000 years, and by 1 million years have essentially gone).

The same as slide 83, but for the first 400,000 years with normal (linear) time and a (correctly) varying volume. As before, the s_ version is the pure (undistorted) sound with broad harmonics. h_ gives the Musical version, with broad harmonics replaced by pure tones, while the hs_ version adds the two together.

The same as slide 85 but for the first 400,000 years at linear (normal) time and with varying (increasing) volume. Once again, the downward slide has been removed to allow our ears to hear the subtly changing chord. The NF3mVD version has the exact (microtonal) pitches while the NF3nVD version has the pitches forced to our tempered scale. In these examples, the volume changes correctly, both overall and for the individual harmonics. (A single octave version wasn't made).

11: From Sound to Stars

Pure (undistorted) sound for the atomic matter (baryons) and dark matter (cdm) around the time of the microwave background (400,000 years). Of course, the dark matter doesn't generate true pressure waves, but this sound has been constructed in the same way as for the atomic matter, from the spectrum of density variations. The dark matter has not been subject to the high pressure forces of radiation, and so it has been able to clump up on very small scales which gives yields the high pitches giving the hiss. Furthermore, because the dark matter has not participated in any pressure oscillations, its spectrum contains no harmonics, hence the hiss is similar to that of "white noise".

Pure (undistorted) sound for times after the microwave background, when the atomic gas is free to fall into dark matter clumps, inheriting its increasingly loud white noise hiss. (The three times are 400,000; 2 million; and 10 million years). In truth, during these later times, the atomic gas has lost most/all its former pressure and so it does not sustain pressure (sound) waves. However, its density structure continues to evolve, and this is what's been used to create these late-time sounds.

12: The First 100 Million Years

Quicktime movies of the evolving sound spectrum for the first 1 million years, including the changing sound waveform and sky color. Time unfolds linearly (normally) in both. The first (lilgli) plots log-loundess (decibels) and plays the sound at constant volume, while the second (lilili) plots linear loudness and plays the sound at (correct) varying volume. The accompanying sounds are also given separately.

Quicktime movies of the evolving sound spectrum for the first 100 million years, including the changing sound waveform and sky color. Time unfolds exponentially in both (2 seconds for each factor of 10 starting at 100 years). The first (lilglg) has a linear frequency axis while the second (lglglg) has a logarithmic frequency axis. The true volume changes too much to render, so a "faked" varying volume is given to the first, to give the feel for the extreme increase in volume. At the end of this time period, 100 million years after the Big Bang, the first generation of stars is about to be born.

13: Expanding Horizons

14: Quantum Hiss

The so-called "Initial Power Spectrum" (IPS) rendered acoustically. This is the spectrum to emerge from inflation and provides the template for all future development of sound and structure. Only as time passed, and causal horizons moved out, could the gas begin to form sound waves. So this sound is really a "latent" sound, waiting to emerge. The second sound file illustrates the response of the Universe, after 400,000 years, to this initial spectrum. After repeating the IPS sound, we then hear the dark matter and the atomic matter. Both have had their higher pitches supressed, though for rather different reasons -- the dark matter only experiences the supression associated with perturbations entering the horizon, while the atomic matter has also experienced a high radiation pressure which prevents significant compression. Thus, the dark matter is transformed into a less shrill hiss, while the atomic matter is deep and laced with harmonics.

15: The CMB Microscope

16: From Sound to the Present

WARNING this is a large, 54 Mega-byte, file. It shows a computer simulation of the formation of a star cluster, and illustrates the kind of processes that might have ocurred 100 million years after the Big Bang during the birth of the first stars. The simulation is by Matthew Bate.

WARNING this is a moderately large, 2.4 Mega-byte, file. It shows a computer simulation of several galaxies merging, and illustrates the kind of processes that might have been common in the first two billion years after the Big Bang. The simulation is by Lars Hernquist (I think?!).

This shows a computer simulation of the formation of a large galaxy cluster. The simulated duration is the entire age of the Universe, starting from an almost uniform distribution of material. In this simulation, only the dark matter is followed, but it also illustrates roughly how the stars would also collect. The simulation is by (yikes, I cant' remember, sorry).

This shows a computer simulation of a giant region, several billion light years across, containing millions of galaxies. The brief movie spans the full age of the Universe, and shows the formation of "Large Scale Structure" -- the Tapestry of galaxies that fills the present day Universe. Recently, the structure of the tapestry has been analysed and the wavelength of the deepest harmonic has been found, a relic of the acoustic era, 14 billion years ago. The simulation is by (yikes, I cant' remember, sorry).

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