Echo of the Universe

Nobel Prizes in Astrophysics & Cosmology - Part 7

(A Twelve Part Series)

John Mather & George Smoot

Cosmology is a science which has only a few observable facts to work with. The discovery of the cosmic microwave background radiation added one — the present radiation temperature of the universe. This, however, was a significant increase in our knowledge since it requires a cosmology with a source for the radiation at an early epoch and is a new probe of that epoch.

-          Robert W Wilson

Temperature map of the CMB measured by the Planck spacecraft

 

The Nobel Prize is equated with the pinnacle of human achievement in both popular perception and professional esteem.  Since it was first awarded in 1901, the annual Nobel Prize for Physics has gone to major contributions in Astrophysics and Cosmology related fields only on eleven occasions. The first six awards (1967, 1974, 1978, 1983, 1993, 2002) were the subjects of earlier articles (see here 1,2,3,4,5,6). The next was in 2006, shared by John C Mather and George F Smoot for their momentous discoveries related to the Cosmic Microwave Background (CMB) Radiation, the afterglow of the Universe.

 

What is CMB

The Cosmic Microwave Background is a faint, nearly uniform glow of microwave radiation that fills the entire universe. It’s the thermal remnant of the hot, dense state of the early universe about 380,000 years after the Big Bang, when electrons and protons combined to form neutral atoms (a moment called recombination). At that time, light could travel freely for the first time — and that light has redshifted over billions of years into microwaves that we detect today.

Discovery

• In 1964, Arno Penzias and Robert Wilson accidentally detected a persistent microwave signal with a radio antenna at Bell Labs (see article on their Nobel Prize winning discovery here).
• They couldn’t explain the noise; it was isotropic (same in all directions) and corresponded to a temperature of about 3 K.
• Simultaneously, theoretical work by Robert Dicke, Jim Peebles, and others predicted such a background as a relic of the Big Bang.
• Penzias and Wilson’s observation provided strong evidence for the Big Bang theory and earned them the Nobel Prize in Physics (1978).

Follow-up Work

Over decades, more precise measurements beginning with COBE (Cosmic Background Explorer) have mapped the CMB in great detail:

COBE (1989–1993)

COBE is the ‘Cosmic Background Explorer’ satellite, a NASA probe launched in 1989 to study the properties and distribution of the CMB. It

• Detected the blackbody spectrum of the CMB with high precision, and
• Found tiny temperature fluctuations (anisotropies).

Graph of CMB spectrum around its peak in the microwave frequency range, a near perfect fit

 

Work of John Mather and George Smoot

They were awarded the 2006 Nobel Prize in Physics “for their discovery of the blackbody form and anisotropy of the cosmic microwave background radiation.” Their work was based on results from NASA’s COBE (Cosmic Background Explorer) probe, launched in 1989.

Scientific Background

The Cosmic Microwave Background (CMB) is relic radiation from the epoch of recombination (~380,000 years after the Big Bang) when photons decoupled from matter.

Theoretical prediction (1940s–1960s):

• Universe should contain residual radiation.
• Spectrum should be thermal (‘Planckian’).
• Tiny fluctuations (~10⁻⁵ level) should exist as seeds of structure formation.

Before COBE:

• CMB was detected in 1964.
• Temperature was measured to be ~2.7 K.
• But precision was insufficient to:
• Confirm exact blackbody shape.
• Detect primordial anisotropies.

COBE changed all that.

Blackbody Spectrum with FIRAS, the Far Infrared Absolute Spectrophotometer

An artist’s view of FIRAS

Scientific Question: Is the CMB exactly a blackbody spectrum?

A blackbody spectrum follows Planck’s law:

where h = Planck’s constant, k = Boltzmann constant, ν = frequency and T = temperature.

Any deviation from this would indicate:

• Energy injection after recombination
• Exotic early-universe physics

FIRAS compared:

• Radiation from the sky, and
• Radiation from a precisely controlled onboard blackbody calibrator

It measured the frequency range: 1–95 cm⁻¹ (≈30–3000 GHz)

Result:

• Temperature: T=2.725±0.002 K
• Spectrum matches Planck curve to better than 1 part in 10⁵

This is the most perfect blackbody spectrum ever measured in nature.

Cosmological Significance

This ruled out many alternative cosmological models (e.g., steady-state variants).
It confirmed that the early universe was in thermal equilibrium.

The energy density of CMB:

ρ_γ​=aT⁴

where a is the radiation constant.

The FIRAS study provided direct evidence of hot Big Bang.

Detection of Anisotropies through DMR (Differential Microwave Radiometers)

Gorge Smoot led this experiment.

Scientific Question

Are there primordial fluctuations in the CMB?

Theoretical prediction: ΔT​∼10⁻⁵ and density fluctuations of the same order.

These tiny fluctuations would later grow via gravitational instability into galaxies and clusters.

Observational Results (1992)

COBE detected ΔT≈30μK

After subtracting dipole anisotropy due to Earth’s motion ~3.3 mK and foreground emission, they did indeed reveal the primordial anisotropies just as expected.

John C Mather (1946 - ) – A Biographical Sketch

Early Life and Education

John Cromwell Mather was born on 7 August 1946, in Roanoke, Virginia, USA. Raised in a family that valued education and intellectual curiosity, Mather developed an early fascination with science. He earned his B S in physics from Swarthmore College (1968) and went on to complete his Ph D in physics at the University of California, Berkeley (1974).

His doctoral work focused on precision measurements in experimental cosmology—skills that would later prove decisive in one of the most important discoveries in modern astrophysics.

Mather’s name is permanently linked with the study of the cosmic microwave background (CMB) — the faint afterglow of the Big Bang.

In the 1970s and 1980s, he became the Project Scientist for NASA’s COBE (Cosmic Background Explorer) mission. Launched in 1989, COBE carried three key instruments:

• FIRAS (Far Infrared Absolute Spectrophotometer) – led by Mather
• DMR (Differential Microwave Radiometers) – associated with George Smoot
• DIRBE (Diffuse Infrared Background Experiment)

Mather’s instrument, FIRAS, made an extraordinarily precise measurement of the CMB spectrum and showed that it is an almost perfect blackbody radiation curve at a temperature of about 2.725 K.

This result was monumental because:

• It confirmed a central prediction of the Big Bang theory.
• It ruled out alternative steady-state cosmological models.
• It established that the early universe had once been in a hot, dense, thermal equilibrium state.

For this achievement, Mather shared the 2006 Nobel Prize in Physics with George F Smoot.

The Nobel citation specifically recognized the discovery of the blackbody form and anisotropy of the cosmic microwave background radiation.

Mather’s contribution specifically concerned the blackbody spectrum confirmation, often described as one of the most precise measurements ever made in physics.

Leadership in Space Astronomy

After COBE, Mather continued to play a central role in space-based astronomy. He became Senior Project Scientist for NASA’s flagship infrared observatory, later to become the James Webb Space Telescope (JWST). Mather was one of the earliest scientific advocates for this and helped guide the mission for decades, through technical and political challenges. The telescope’s extraordinary success stands as testimony to his enduring legacy.

Mather is known for:

• Exceptional experimental precision
• Strong collaborative leadership
• Long-term commitment to major scientific missions
• Ability to bridge theoretical cosmology and instrumentation

His work transformed cosmology from a speculative discipline into a precision science.

Honors and Recognition

Beyond the Nobel Prize, Mather has received:

• The NASA Distinguished Service Medal
• The Shaw Prize in Astronomy
• Membership in the U.S. National Academy of Sciences

He remains a leading voice in cosmology and space science.

Legacy

Mather’s confirmation of the CMB’s perfect blackbody spectrum is often compared to a “Rosetta Stone” for cosmology. It provided the thermodynamic fingerprint of the Big Bang and cemented modern cosmology on firm experimental foundations.

George F Smoot (1945 – 2025) – A Biographical Sketch

Early Life and Education

George Fitzgerald Smoot III was born on 20 February 1945, in Yukon, Florida, USA. He studied mathematics and physics at the Massachusetts Institute of Technology (MIT), earning his undergraduate degree in 1966. He then completed his Ph D at MIT in 1970, working on experimental particle physics.

His early research included work on antimatter and cosmic rays, but he soon shifted toward cosmology — particularly the experimental study of the early universe.

Pioneer of Cosmic Structure Measurements

Smoot is best known for his leadership in detecting tiny temperature fluctuations (anisotropies) in the cosmic microwave background (CMB), the relic radiation from the Big Bang.

He played a central role in NASA’s COBE (Cosmic Background Explorer) satellite mission, launched in 1989. Smoot led the team responsible for the DMR (Differential Microwave Radiometers) instrument

While John Mather’s FIRAS instrument confirmed the CMB’s perfect blackbody spectrum, Smoot’s DMR instrument made a complementary and equally historic discovery. In 1992, his team announced the first detection of minute temperature variations in the CMB — differences of only about one part in 100,000.

These anisotropies were crucial because:

• They represented the “seeds” of galaxies and large-scale structure.
• They provided direct evidence that small density fluctuations existed in the early universe.
• They strongly supported inflationary cosmology models.

The discovery was famously described as: “Looking at the face of God.”

Nobel Prize

For these discoveries, Smoot shared the 2006 Nobel Prize in Physics with John C Mather.

The Nobel citation recognized:

• The discovery of the blackbody form (Mather)
• The discovery of anisotropy in the cosmic microwave background radiation (Smoot)

Together, these findings transformed cosmology into a precision, data-driven science.

Later Career and Contributions

After COBE, Smoot continued his research at the University of California, Berkeley, contributing to subsequent cosmology missions and large-scale structure studies. He was involved in:

• Balloon-borne and satellite experiments refining CMB measurements
• Cosmological data interpretation from missions like WMAP and Planck
• Theoretical and observational work related to cosmic inflation

He also became known for public engagement in science and international collaborations, including academic positions in Europe and Asia.

Scientific Impact

Smoot’s measurement of CMB anisotropies:

• Confirmed predictions that tiny primordial fluctuations would grow under gravity into galaxies and clusters.
• Provided empirical support for inflationary cosmology.
• Laid groundwork for later high-precision missions such as WMAP and Planck.

Today, the CMB anisotropy map is considered one of the most important images in modern science.

Personality and Public Role

Smoot is known for:

• Strong experimental leadership
• Ambitious, large-scale scientific projects
• Effective communication of cosmology to the public

He has written popular science books explaining the origin and evolution of the universe, helping bring cosmology to a wider audience.

Legacy

If Mather gave cosmology its thermal proof of the Big Bang, Smoot revealed its structure — the tiny ripples that grew into galaxies, stars, and eventually observers like us.

 

Epilogue: Follow-up work on CMB

WMAP (2001–2010)

WMAP is the ‘Wilkinson Microwave Anisotropy Probe’, a NASA mission that

• Produced detailed, full-sky maps of CMB temperature variations.
• Allowed precise determination of cosmological parameters (age of universe, composition, geometry).

WMAP Spacecraft

Planck (2009–2013)

Planck was a European Space Agency (ESA) space observatory that

• Provided the most detailed CMB survey to date.
• Measured the temperature and polarization anisotropies with unprecedented precision.

These anisotropies are the seeds of large-scale structure — the galaxies and clusters we see today.

Planck Spacecraft

Current Status

The CMB is now one of the most well-measured observables in cosmology.
It shows that the universe is:

• ~13.8 billion years old
• Flat (in overall geometry)
• Composed of ~5% ordinary matter, ~27% dark matter, ~68% dark energy

Current work focuses on:

• CMB polarization, especially B-modes, which could reveal primordial gravitational waves from inflation.
• Ground-based telescopes (e.g., the South Pole Telescope, Simons Observatory) and future missions aiming for even finer measurements.

Why it Matters

    The CMB is a snapshot of the early universe — a cornerstone of modern cosmology that underpins our understanding of the origin, composition, and evolution of the cosmos.

 

 

Goodbye! Comet 3I/ATLAS

…as you leave behind a silent triumph for science

 

“A lie can travel halfway around the world before the truth puts on its shoes”

 - Anon

Current location of comet 3I/ATLAS

This is the fourth guest article from Ilavenil T under my banner.  She follows up on her previous one (see here) on how pseudoscientific claims can be put under the microscope with Carl Sagan’s Boloney Kit, with particular reference to solar system’s third interstellar visitor comet 3I/ATLAS, and attempts to separate the grains of sensible science from the chaff of pseudoscience.    

Ilavenil T

Comet 3I/ATLAS was the third (known) interstellar object to enter our Solar System, and after months of excited observations from the astronomical community, is now on the way out of the Solar System. Interstellar objects like these are akin to the storytellers who travelled the land in every culture – teaching lessons and moving on! Farewell to the visitor who brought us so much knowledge! What happened as expected and what didn’t? This article is a look at the scientific and pseudoscientific claims and insights.

Observations of Comet 3I/ATLAS

From the time 3I/ATLAS was discovered, and its rare interstellar nature recognized, there has been international collaboration between observatories and institutions on an unprecedented scale to extract as much information as possible about this extraordinary visitor amongst us, visible only through large telescopes. A similar effort was made for the earlier interstellar discoveries, 1I/Oumuamua and 2I/Borisov. 

Here’s a representative list of the observatories and organizations which followed Comet 3I/ATLAS in its eccentric path ^[2]: 

Survey/Discovery Organizations

·      Asteroid Terrestrial-impact Last Alert System (ATLAS)

·      NASA

·      International Astronomical Union's Minor Planet Center (MPC)

Observatories and Telescopes

·      ATLAS survey telescope at Río Hurtado, Chile (observatory code W68)

·      Gemini North & South telescopes

·      Zwicky Transient Facility (ZTF, observatory code I41)

·      Deep Random Survey (X09) at Chile

·      Lowell Discovery Telescope (G37) at Arizona

·      Canada–France–Hawaii Telescope (T14) at Mauna Kea

·      Teide Observatory's Two-meter Twin Telescope

·      Weizmann Astrophysical Observatory (M01)

·      Very Large Telescope

·      Vera C Rubin Observatory in Chile

·      NASA Infrared Telescope Facility

·      Hubble Space Telescope

·      James Webb Space Telescope (JWST)

·      Gran Telescopio Canarias

·      1.2m infra-red telescope on Mount Abu, India

·      Space Missions and Spacecraft

·      Transiting Exoplanet Survey Satellite (TESS)

·      SPHEREx mission

·      ExoMars Trace Gas Orbiter (TGO)

·      Colour and Stereo Surface Imaging System (CaSSIS)

·      Mars Reconnaissance Orbiter

·      Tianwen-1 (China)

Research Institutions

·      Instituto de Astrofísica de Canarias (IAC)

·      Lowell Observatory

·      California Institute of Technology

·      Physical Research Laboratory, India

·      European Space Agency (ESA)

·      China National Space Administration (CNSA) 

Discoveries and Predictions 

Here is a summary of the major findings about the comet: 

The comet reached perihelion as predicted on October 29, 2025. Closest approaches to Venus, Mercury and Mars were as predicted (see table below), with the calculations becoming more precise as the dates approached ^[2]. 

Object	Date
Mars	2025-Oct-03 04:38 UT
Mercury	2025-Oct-08 02:43 UT
Venus	2025-Nov-03 05:56 UT
Jupiter (Expected)	2026-Mar-16 12:22 UT

The results now available point to a fascinating origin for the comet.

Yiyang Guo et al have looked at the possible gravitational perturbations which could have led to the orbital parameters and speed of 3I/ATLAS. After looking at 30 million stars in the Gaia catalogue, they have identified 25 which could have led to the orbital characteristics of 3I/ATLAS, and conclude that the comet originated in the thin disk of the Milky Way. 

Hopkins et al, on the other hand, have used the Ōtautahi–Oxford population model of interstellar objects, which takes into account not only the Gaia stars but also galactic dynamics and protoplanetary disk chemistry to deduce that the comet originated in the thick disk of the Milky Way. If it is indeed from the thick disk, 3I/ATLAS is probably more than 7 billion years old ^[3][4]. 

This is an illustration of how different “modes of attack” can yield different results on the same data. There will be consensus once there is more data, or when one methodology emerges superior to the other. 

Composition of 3I/ATLAS 

Observations of the coma of comet 3I/ATLAS show the presence of a higher concentration of carbon dioxide than in comets that originate within the Solar System (see graph below). The proportion of carbon monoxide is also high ^[5].

According to a paper submitted to the astrophysical journal, along with the high carbon dioxide and carbon monoxide concentrations, the spectroscopic data indicate “red spectral slopes” that show that the comet was irradiated by galactic cosmic rays. These rays irradiate CO₂ to CO, while synthesizing organic-rich crusts ^[6]. 

The proportion of methanol relative to hydrogen cyanide is among the highest ever recorded in any comet. This indicates that other protoplanetary disks (the disks of matter orbiting a star that later coalesce into planets, satellites, etc.,) can have very different compositions ^[7][8]. 

An interesting point here – the comet C/2016 R2, a long period comet that originated in the Solar System, also exhibits the high concentration of methanol relative to hydrogen cyanide and a high concentration of carbon dioxide. This does not reduce the significance of these discoveries, but contributes to strengthening some of the theories on the formation of comet C/2016 R2.

Also intriguing are traces of nickel vapor. Nickel is not a rare finding, but it is usually accompanied by iron ^[8]. 

As it approached the Sun, the sublimation of water in the nucleus led to jets and ice volcanoes on the surface, as submitted in a paper dated November 24, 2025 ^[4]. These cryovolcanoes might be the result of the metals corroding and acting as catalysts to start off energetic Fischer-Tropsch reactions ^[9]. 

[The Fischer–Tropsch process (FT) is a collection of chemical reactions that converts a mixture of carbon monoxide and hydrogen, known as syngas, into liquid hydrocarbons. These reactions occur in the presence of metal catalysts, typically at temperatures of 150–300°C and pressures of one to several tens of atmospheres.] 

Are there more questions than answers? Certainly, yes. And there will be answers coming as the normal progress of scientific discovery unfolds. This is a quiet triumph of the scientific method. Scientific research is not a sprint but a marathon. It is to be expected that many more papers will be published this year, as the results are analysed and peer-reviewed.  Databases show promising numbers: Arxiv.org lists 78 articles on 3I/ATLAS that have been submitted or published, and Google Scholar, 518. 

The Predictions That Never Came True 

It’s now time to look back on the pseudoscience that heralded the visit of 3I/ATLAS. As we know, no spaceship came from behind the Sun to attack us as insinuated by some scaremongers. But what about the other claims? 

Let me now go back to table below, from the paper by Loeb et al. This paper was rehashed in a number of YouTube videos and articles. 

These are the reasons put forward for the theory that Comet 3I/ATLAS is of technological origin:

As stated in the previous article (see here), points 1 – 3 were already debunked at the time of writing. Let’s look at points 4 – 9 now: 

Quite obviously, there were no interceptions of planets, no solar sails and no spaceship attacking the Earth. There was no acceleration observed other than that expected through the natural processes of gravity and outgassing. 

Avi Loeb

Dr Loeb has now published yet another essay on the comet, where he paraphrases the actual scientific discoveries and conveniently leaves out all his failed predictions. He ends the essay with an ominous “Are we missing something” – a sentence which is the “most highlighted” according to the website. He has also been interviewed by Fox News – an over 20-minute interview where he essentially says nothing, but keeps repeating the word “anti-tail” 

His Harvard page reveals that Dr Loeb has written close to 60 articles on 3I/ATLAS. I’m listing some of them here to show how he merrily “moves the goalposts” even as his theories are discredited by science. 

His writings leading up to perihelion: 

"Is the Interstellar Object 3I/ATLAS Alien Technology?" (July 16, 2025)

"How to Distinguish a Population of Interstellar Rocks from a Fleet of Spacecraft?" (September 8, 2025)

"Was the Wow! Signal Emitted from 3I/ATLAS?" (September 28, 2025)

"The Acid Test of 3I/ATLAS at Perihelion" (October 28, 2025) 

After perihelion occurred as predicted, without any alien attack: 

"Afterthoughts on the Non-Gravitational Acceleration of 3I/ATLAS at Perihelion" (October 31, 2025) 

Starting off the next story… 

"Do the Anomalies of 3I/ATLAS Flag Alien Technology or an Unfamiliar Interstellar Iceberg?" (November 17, 2025)

"3I/ATLAS is Hiding Behind a Veil of Dust" (December 27, 2025)

"If 3I/ATLAS is a Comet, Why Would the CIA Neither Deny, Nor Confirm the Existence of Records on It?" (January 5, 2026) 

The frightening part

Comet 3I/ATLAS is only the third known interstellar object, but there is plenty of reason to expect more in the future. Is every interstellar spacecraft, or indeed every breakthrough discovery in science going to be met with speculation and pseudoscience, not curiosity and wonder? 

This is the Google Trends graph for interest in Comet 3I/ATLAS:

As you can see, the interest peaked with the conspiracy theories, and died down when the pseudoscience failed. 

The people who produced these articles and videos have not been taken to task by anyone. Apparently, the public are happy to read pseudoscience, believe it, and when it fails, to move on. Pseudoscientists also have the luxury of keeping their output “current” – one of Loeb’s essays was a response to a celebrity posting something on social media! 

Why is Avi Loeb allowed to keep moving the goalposts – to keep changing his narrative when there is a system to keep scientists accountable? 

This exemplifies the quote at the beginning of this article - “A lie can travel halfway around the world before the truth puts on its shoes.” 

References:

1. Prasad, S. N. “Interstellar Visitor 3I/ATLAS – Alien Technology? Is It Just Much Ado About Nothing?”
2. “3I/ATLAS.” Wikipedia: The Free Encyclopedia, 2 Feb. 2026, en.wikipedia.org/wiki/3I/ATLAS. Accessed 2 Feb. 2026.
3. JWST Detection of a Carbon Dioxide Dominated Gas Coma Surrounding Interstellar Object 3I/ATLAS. Zenodo, zenodo.org/records/16941949. Accessed 2 Feb. 2026.
4. Trigo-Rodríguez, Josep M., et al. “Spectrophotometric Evidence for a Metal-Bearing, Carbonaceous, and Pristine Interstellar Comet 3I/ATLAS.” arXiv, 24 Nov. 2025, arxiv.org/abs/2511.19112. Accessed 2 Feb. 2026.

5.     Álvarez-Candal, A., et al. “X-SHOOTER Spectrum of Comet 3I/ATLAS: Insights into a Distant Interstellar Visitor.” Astronomy & Astrophysics, vol. 700, 2025, aanda.org/articles/aa/full_html/2025/08/aa56338-25/aa56338-25.html. Accessed 2 Feb. 2026.

6.     Guo, Yiyang, Luyao Zhang, Fabo Feng, Zhao-Yu Li, Anton Pomazan, and Xiaohu Yang. “Search for Past Stellar Encounters and the Origin of 3I/ATLAS.” The Astronomical Journal, vol. 170, no. 6, 2025, article 362, doi:10.3847/1538-3881/ae1833. Accessed 2 Feb. 2026.

7.     Loeb, Abraham, Adam Hibberd, and Adam Crowl. Is the Interstellar Object 3I/ATLAS Alien Technology? Harvard-Smithsonian Center for Astrophysics, lweb.cfa.harvard.edu/~loeb/HCL25.pdf. Accessed 2 Feb. 2026.

8.  Loeb, Avi. “The Massive Nucleus of 3I/ATLAS and Its Puzzling Methane Outgassing, Based on  New Data From the Hubble and Webb Telescopes.” Medium, 2026, avi-loeb.medium.com/the- massive-nucleus-of-3i-atlas-and-its-puzzling-methane-outgassing-based-on-new-data-from-the-72e540d8fe46. Accessed 2 Feb. 2026.
9.  ChicagoLIVE. “Avi Loeb: CIA Would Neither Confirm nor Deny Records on 3I/ATLAS …”  YouTube, 2025, www.youtube.com/watch?v=KOt6R8-i30U. Accessed 2 Feb. 2026.