Special Relativity: Why speed of light is constant ? Length and Time Dilation

In our everyday life, things move pretty slowly compared to the speed of light. For example, the top speed of the world’s fastest train, the Shanghai Maglev, is 460 km/h, which is about 0.128 km/s. The NASA/USAF X-15, the fastest jet ever, reached a speed of 4,520 mph, or approximately 1.26 km/s. But these speeds are tiny compared to the speed of light, which races along at a massive 299,792.458 km/s.

To put this in perspective, the speed of light is about 2.34 million times faster than the Shanghai Maglev and it’s around 238,000 times faster than the X-15 jet.

This is why we’re used to thinking of the world as stable and predictable. However, in the late 1800s, scientists made a groundbreaking discovery about light that changed everything.

The Michelson-Morley Experiment: A Surprising Result

Figure 0: The figure illustrates the hypothetical "aether wind" caused by Earth's orbital motion. According to the aether theory, this would affect light's speed, making it faster when traveling with the wind and slower when moving against it.

Scientists once believed that light, like sound, must travel through some kind of medium, which they called the aether. This mysterious aether was thought to be an invisible substance filling all of space, acting as a carrier for light waves. To test this idea, Albert Michelson and Edward Morley set up an ingenious experiment in 1887 to see if they could detect the effects of Earth's motion through the aether.

Here’s how they approached it: if the aether really existed, then Earth, moving through space at about 107,000 km/h (or around 30 km/s) in its orbit around the Sun, would be plowing through it, as seen in Figure 0 and 1. As Earth moved through this aether “wind,” they reasoned that light traveling in the direction of Earth’s motion would be affected—just like a boat’s speed in a river changes based on the river current. For example, a boat moving downstream with the current moves faster than one going upstream against it. If light behaved similarly, it would travel slightly faster when moving with the "aether wind" and slower when moving against it.

Figure 1. Image of Michelson Morley Interferometer. The light beam is split in two perpendicular beams. The path of the beams should get affected by the presence of ether which can be measured by the detector.
Source : faculty.etsu.edu

To test this, Michelson and Morley designed a setup using a special device called an interferometer as shown in Figure 1. This device split a single light beam into two perpendicular beams, one moving in the same direction as Earth's motion and the other moving perpendicular to it. After traveling different paths, the beams would be brought back together and interfere with each other. If the speed of light was affected by the aether, even by a tiny amount, this interference would show up as a change in the light patterns. 

But to their surprise, no matter how they oriented their equipment or what direction the beams traveled, the speed of light stayed the same. There was no detectable difference between the light moving "with" or "against" Earth's motion through the supposed aether.

This unexpected result shocked the scientific community. It was as if the aether didn’t exist at all, or if it did, it had no effect on light’s speed. This experiment ultimately led to the radical conclusion that the speed of light is a universal constant, independent of any “aether” or the motion of the observer. This realization was a crucial stepping stone toward Einstein’s theory of special relativity, which showed that space and time adjust in ways that keep the speed of light constant for all observers.

Einstein’s Big Idea

Albert Einstein took this discovery further. If the speed of light is always constant, then something else has to change to make that possible. Einstein realized that for the speed of light to stay the same, measurements of time and space must change. This led to two surprising effects: time dilation and length contraction.

What is Time Dilation?

Time Dilation: Slower Time for Moving Objects

Imagine time as a clock ticking away seconds, but this clock doesn’t tick the same way for everyone. In Einstein’s theory of relativity, time dilation means that time actually passes more slowly for objects in motion relative to a stationary observer.

How It Works

Figure2. This figure shows the difference in path of the light in the rest frame of reference (on left) and the moving frame of reference (right). The object in motion travels a longer path as compared to the object at rest. However, as the speed of light is a constant, the time taken by the moving object is shorter as compared to the object in rest.
Source: https://commons.wikimedia.org/wiki/User:Sacamol

To understand time dilation, let’s revisit our example of your friend on a high-speed train in figure2.  Both you and your friend carry clocks that tick by counting the time it takes for a pulse of light to bounce between two mirrors. This “light clock” gives a consistent measure of time in both your and your friend’s frames.

However, from your perspective, the light in your friend’s clock travels a longer, diagonal path, since it’s moving along with the train. But according to Einstein’s discovery, the speed of light stays constant, so the light pulse can’t travel faster in your friend’s clock to keep up with the train. Instead, it takes more time for the light to bounce between mirrors, meaning your friend’s clock ticks slower than yours.

So, from your perspective, as the observer on the platform, your friend’s time appears to slow down. This isn’t just an illusion but a real effect: time truly passes more slowly for objects moving at high speeds relative to you. Below is the real -life example for the time dilation

Real-Life Example: Cosmic Rays and Muons

We see time dilation in action with cosmic rays. When cosmic rays hit Earth’s atmosphere, they produce particles called muons, which decay very quickly—usually within about 2.2 microseconds. Muons travel at nearly the speed of light, so if they experienced “normal” time, they wouldn’t survive long enough to reach the ground. However, because they’re moving so fast, time for them slows down relative to an observer on Earth. As a result, they live long enough to be detected at sea level.

In summary, time dilation tells us that moving clocks run slower, which is why muons can travel far further than we’d expect based on their short lifespans.

What is Length Contraction?

Length Contraction: Shrinking Distances for Fast-Moving Objects

Length contraction is the counterpart to time dilation and affects distances rather than time. When an object moves at a high speed, its length appears to shorten in the direction of its motion relative to a stationary observer

How It Works

Let’s return to your friend on the train. From your friend’s point of view, they’re stationary, and it’s you who are moving backwards. According to Einstein’s theory, you both see each other’s clocks ticking more slowly, but that’s not all: your friend also sees the length of the train and everything around it shrinking in the direction of motion.

This effect is real. Just like with time dilation, length contraction is needed to keep the speed of light constant. Since you both agree on the speed of light, any distance measured along the direction of motion has to adjust. So, your friend on the train experiences a “shortened” view of the distances they travel compared to what you see.

Real-Life Example: The Muon’s Journey (Revisited)

For the muon, length contraction provides an alternative explanation for why it can reach Earth’s surface. From the muon’s perspective, it has a much shorter distance to travel because the atmosphere itself appears compressed in the direction of its motion. This shortening effect, combined with time dilation, ensures that the muon can complete its journey to the surface before it decays.
Why Time Dilation and Length Contraction Happen

Both time dilation and length contraction arise from the Lorentz transformations- the mathematical equations used to switch between the perspectives of observers moving at different velocities. These transformations adjust time and space measurements so that the speed of light remains the same for everyone, regardless of their motion.

In a sense, time dilation and length contraction are the universe’s way of keeping the speed of light constant across different frames of reference. So even if two people are moving relative to each other, they both measure light as moving at the same speed, but they end up with different measurements for time intervals and distances.

One strange outcome of this is that two observers moving relative to each other won’t agree on the timing or simultaneity of events. Even the amount of time that passes can seem different! While it sounds confusing, these effects are now a fundamental part of physics, showing us that reality itself bends to keep the speed of light constant.

Living Longer with Einstein's Special Relativity 

Special Relativity even offers a fascinating way to “live longer,” though not in the usual sense of extending biological lifespan. As the time slows down for anyone moving close to the speed of light, an astronaut traveling at 90% the speed of light might experience only 5 years passing on their ship, while 10 or more years would pass on Earth. To the astronaut, life feels normal, but when they return, they’ll have aged less than those who stayed behind. This effect, famously illustrated by the “Twin Paradox,” shows how high-speed space travel could, in theory, allow humans to outlive their peers on Earth. In fact, astronauts on the ISS already experience this in tiny amounts as they come back just a fraction of a second “younger” than if they had remained on Earth.

In short, the Michelson-Morley experiment set us on a path to understanding the true nature of space and time. Thanks to Einstein, we now know that our universe isn’t as straightforward as it seems - space and time are flexible, changing based on speed and perspective. And it all started with the speed of light.

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Research Paper Simplified : Galactic Archaeology with Gaia: Alis J. Deasona , Vasily Belokurov

Exploring the Milky Way's evolution has become more exciting thanks to the Gaia mission. Let’s break down what this revolutionary mission reveals about our Galaxy's past!

Summary of the Blog:

The Gaia mission has transformed our understanding of the Milky Way’s evolution by mapping over a billion stars. It reveals the galaxy’s hidden history, particularly through the discovery of the Gaia-Sausage-Enceladus (GSE) merger, which occurred 8–11 billion years ago and significantly shaped the inner stellar halo. Gaia's precise measurements provide insights into stellar orbits and chemical compositions, allowing scientists to distinguish between stars formed within the Milky Way and those from GSE. This mission enhances our knowledge of the Milky Way's structure and evolution, offering a clearer picture of the cosmic events that have shaped our galaxy over billions of years.


In this blog, we will explore several key topics related to the Milky Way’s evolution. First, we’ll examine the stellar halo and its role as a fossil record of past mergers. Then, we will discuss the Gaia-Sausage-Enceladus (GSE) merger, highlighting the evidence for its significance in shaping the Milky Way’s structure. Next, we’ll analyze the chemical signatures of different stellar populations, which reveal their origins and formation histories. Finally, we’ll showcase how Gaia's innovative data techniques have revolutionized galactic archaeology, enhancing our understanding of the Milky Way’s formation and broader galaxy development. Join us as we uncover this fascinating narrative!

Introduction: The Hidden History of the Milky Way

Figure 1: Artistic Representation of Milky Way

The Milky Way, like a cosmic archaeologist, carries the remnants of its formation and evolution (Fig.1). Over billions of years, it has consumed smaller galaxies, leaving behind debris in the form of stars and dark matter. This "stellar halo" acts like a fossil record, telling the story of these galactic mergers and the Milky Way’s dynamic history. Stars act as fossil records of the past, preserving information about their origins, motions, and chemical compositions.

Figure 2: Gaia Observers Milky Way

In this image, milky way can be seen as a brownish band in the background with Gaia Satellite in the foreground.

Image Source : Wikimedia Commons

The Gaia Mission, launched by the European Space Agency, has transformed how we study these remnants (Figure 2). By providing highly detailed maps of the positions, motions, and chemical compositions of over a billion stars, Gaia gives scientists an unprecedented view of our Galaxy Milky way.

Key Questions for Discussion:

• How has the Milky Way grown over billions of years?
• What role do mergers, like Gaia-Sausage-Enceladus (GSE), play in this process?
• How does the Gaia mission allow us to reconstruct the Galaxy’s history?
• Key Discoveries in Galactic Archaeology

1. The Stellar Halo: A Galactic Fossil Record

The stellar halo is a diffuse, spherical region of stars surrounding the Milky Way. It holds clues about the galaxies our Galaxy devoured over time.

Pre-Gaia Observations:

Earlier studies provided hints of a stellar halo, but the data was sparse and incomplete. Astronomers used models to guess the properties of these stars, often based on limited samples from telescopes like SDSS. Also, the most studies relied on indirect methods to infer the orbits and origins of stars.

The Gaia Revolution 

 The Gaia mission provides precise astrometric data, including positions, proper motions, parallaxes, and radial velocities for over 1 billion stars, enabling detailed reconstructions of their orbits and origins.

Post-Gaia Era:

With Gaia’s precise data, astronomers discovered that most of the inner stellar halo (within 20 kpc of the Galactic center) is dominated by debris from a single massive dwarf galaxy, referred to as Gaia-Sausage-Enceladus (GSE).

2. The Discovery of Gaia-Sausage-Enceladus (GSE)

Figure 3. A visualization of the moment of impact between the MW’s progenitor and the Gaia Sausage (or Gaia-Enceladus) (credit: Instituto de Astrofísica de Canarias).

The GSE is one of the Milky Way’s largest mergers, occurring about 8–11 billion years ago (Figure 3). Its debris dominates the Milky Way’s inner stellar halo (r < 20 kpc). Here’s why it’s important:

Key Evidence for GSE:

1. Radial Orbits of Stars: 

GSE stars exhibit highly eccentric orbits, with elongated paths that repeatedly bring them close to the Galactic center. The radial velocity distribution of GSE stars shows two prominent "lobes," indicating their highly eccentric motion. The symmetry of these lobes supports the idea of a single progenitor contributing to the inner halo.

2. Chemical Fingerprints:

Figure3. X-axis represents Fe/H and Y-axis represents [α/Fe] in upper panel and number of stars in the lower panel. Black Dots represent the milky way stars that formed in-situ while the blue stars are associated with GSE. Solid (dotted) lines show the distribution of [Fe/H] when high-α stars are excluded (included). Image Credits: arXiv:2402.12443

Chemical composition plays a vital role in identifying stellar populations. Stars from the Milky Way and accreted galaxies differ in their ratios of heavy elements, such as alpha-elements (like magnesium) and iron.

Stars with higher [Fe/H] are more metal-rich, meaning they formed later in a galaxy’s history when there was more iron available from previous generations of supernovae. [α/Fe] is the ratio of alpha elements (α) to iron (Fe). Alpha elements include magnesium, silicon, calcium, and oxygen, which are primarily produced by massive stars in Type II supernovae. Higher [α/Fe] Indicates rapid star formation because massive stars dominate in enriching the environment before Type Ia supernovae contribute significant iron.

Figure 3 shows the metallicity distribution with [Fe/H] vs. [α/Fe]. 

The distribution of stars in chemical space ([Fe/H] vs. [α/Fe] shows distinct groups. This allows astronomers to separate in-situ stars (formed in the Milky Way) from accreted stars like those from GSE. Milky Way stars have higher [Fe/H], varying [α/Fe] from GSE stars with lower [Fe/H], higher [α/Fe] This chemical distinction helps identify which stars belong to the Milky Way and which came from GSE.

3. Apocenter Pile-Up:

Figure4. The figure represents the variation of density with distance. Apocenter distributions (Fig. 8) confirm that GSE debris dominates within ~20 kpc.Image Credits: arXiv:2402.12443

 

In a galaxy, the apocenter pile-up is a phenomenon that can lead to distinctive features in the stellar halo. This occurs when stars build up at the apocenter of a common dwarf progenitor, resulting in a broken density profile. The stellar debris deposited during this event has similar apocenters, which is responsible for the stellar halo break. The apocenters of GSE stars cluster around ~20 kpc, aligning with the break in the stellar halo’s density profile. Figure 4 in the paper shows the apocenters of GSE stars overlap with the observed density break, reinforcing the idea that GSE debris dominates the inner halo.

3. Globular Clusters (GCs) and GSE

GCs are dense star clusters often associated with their host galaxies. In the Milky Way, they provide additional clues about past mergers. Several GCs on highly eccentric orbits are linked to GSE.

These clusters share orbital characteristics with GSE stars, confirming their common origin.

Figure 7 in the paper shows the peri- and apocenter distances of GSE’s GCs overlap with those of GSE stars, indicating a shared history.

4. Implications of GSE for Galactic Evolution

• GSE was the last major merger, significantly shaping the Milky Way’s inner halo.
• Its debris dominates the inner halo (r < 20 kpc).
• The GSE merger influenced the Milky Way’s dark matter halo, contributing to its current structure.
• GSE brought globular clusters (GCs) into the Milky Way.Figure Reference (Fig. 7 in paper): Many GSE globular clusters have highly eccentric orbits, consistent with GSE stars.

5. How Gaia Revolutionized Galactic Archaeology

• Before Gaia, astronomers relied on indirect methods and limited data to study the Galaxy’s structure. Now, Gaia provides:
• 6D Maps: Positions, velocities, and chemical compositions of stars.
• High Precision: Data that allows scientists to track the orbits of stars and identify their origins.
• Complementary Surveys: Combining Gaia data with spectroscopic surveys like APOGEE and SDSS reveals even more details about star chemistry and motion.

Why This Matters

• Understanding the Milky Way’s formation gives us a glimpse into the broader universe:
• The Milky Way’s mergers are part of a universal process of galaxy formation.
• Stellar motions reveal the distribution of invisible dark matter in the Galaxy.
•  The chemical fingerprints of stars teach us about the life cycles of galaxies.

The Gaia mission has opened a new chapter in studying the Milky Way’s history. By combining stellar motion, chemistry, and models, scientists can reconstruct the story of our Galaxy’s growth and evolution.

References :

[1] Galactic Archaeology with Gaia, Jul 2024, Alis J. Deason , Vasily Belokurov

arXiv:2402.12443 [astro-ph.GA]

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The Fermi Paradox: Where are the Aliens?

The Fermi Paradox presents one of the most profound and perplexing questions in the scientific community: Where is everyone? This seemingly simple inquiry touches the very core of our understanding of the universe, the nature of life, and the limits of human knowledge. Named after the Italian-American physicist Enrico Fermi, who first articulated the paradox during a casual lunch conversation in 1950, it challenges our assumptions about the existence of extraterrestrial civilizations. Despite the vastness of the universe and the high probability of life-sustaining planets, the absence of evidence for advanced extraterrestrial life remains a profound mystery.

The Scale of the Universe: A Statistical Perspective

The paradox gains depth when we consider the scale of the universe. The observable universe contains approximately 100 billion galaxies, each with an estimated 100 billion stars. If even a tiny fraction of these stars host planets within the habitable zone—regions where conditions are right for liquid water and potentially life—the number of potentially life-supporting planets could be staggering.

The Drake Equation, formulated by Frank Drake in 1961, provides a framework for estimating the number of active, communicative extraterrestrial civilizations in our galaxy. The equation considers factors such as the rate of star formation, the fraction of stars with planetary systems, the number of planets that could potentially support life, and the likelihood of life developing intelligence and technology. While the values for these variables are highly uncertain, even conservative estimates suggest that our galaxy alone could harbor millions of civilizations.

The Great Silence: Why Haven’t We Heard Anything?

Given the statistical likelihood of numerous advanced civilizations, the Fermi Paradox forces us to confront the *Great Silence*: the absence of detectable signals or evidence of extraterrestrial life. Several hypotheses have been proposed to explain this silence, ranging from the limitations of our detection technologies to the possibility that advanced civilizations self-destruct before becoming detectable.

 1. The Rare Earth Hypothesis

One of the most discussed explanations is the *Rare Earth Hypothesis*, which suggests that the emergence of complex life is an extremely rare event, even in a galaxy teeming with planets. According to this view, Earth's conditions might be uniquely favorable, involving a series of improbable events and circumstances, such as the presence of a large moon, a stable climate, and the right chemical composition.

 2. The Great Filter

Another compelling concept is the *Great Filter*, a hypothetical stage in the evolution of life that is extraordinarily difficult to pass. This filter could be behind us, meaning the emergence of intelligent life is exceedingly rare, or it could be ahead of us, implying that advanced civilizations inevitably encounter a catastrophic obstacle that prevents them from reaching a stage where they can communicate across interstellar distances. If the latter is true, the Great Filter represents a dire warning for humanity's future.

3. Technological Limitations and the Zoo Hypothesis

Our current technological limitations might also play a significant role in the paradox. The vast distances between stars mean that even light-speed communication would take years, if not centuries, to traverse the gulf between potential civilizations. Additionally, our search methods, which rely heavily on detecting radio waves, might be fundamentally flawed if advanced civilizations use entirely different methods of communication.


The *Zoo Hypothesis* offers a more speculative solution: advanced extraterrestrial civilizations may deliberately avoid contact with us, perhaps to allow for our natural evolution and cultural development. In this scenario, Earth might be akin to a cosmic zoo or nature reserve, observed but not interfered with by superior beings.

 4. Self-Destruction and the Dark Forest Theory

The *Self-Destruction Hypothesis* posits that advanced civilizations tend to annihilate themselves through technological catastrophes, such as nuclear war, environmental collapse, or uncontrolled artificial intelligence. This idea aligns with the Dark Forest Theory, which portrays the universe as a hostile environment where civilizations remain silent and hidden to avoid detection by potentially malevolent others. In such a universe, broadcasting one's presence could invite existential threats.

The Search for Extraterrestrial Intelligence (SETI)

                                                   Credit: Bill Saxton, NRAO/AUI/NSF

Despite the challenges posed by the Fermi Paradox, the search for extraterrestrial intelligence (SETI) remains a major scientific endeavor. Since the first SETI experiments in the 1960s, researchers have scanned the sky for signals that might indicate the presence of intelligent life. The advent of new technologies, such as the Square Kilometre Array (SKA) and advancements in machine learning, promises to enhance our ability to detect faint signals and identify patterns that could signify alien technology.


Moreover, the discovery of exoplanets—planets orbiting stars outside our solar system—has invigorated the search for life. Missions like the Kepler Space Telescope have identified thousands of exoplanets, some of which are located in the habitable zone of their parent stars. Future missions, such as the James Webb Space Telescope, aim to analyze the atmospheres of these exoplanets for bio-signatures, such as oxygen or methane, that might indicate the presence of life.

Conclusion: The Fermi Paradox as a Catalyst for Exploration

The Fermi Paradox remains unresolved, and perhaps it will continue to be a subject of speculation and debate for generations. However, it serves as a powerful catalyst for scientific exploration, driving humanity to seek answers to fundamental questions about our place in the universe. Whether we are truly alone or one of many civilizations scattered across the cosmos, the search for extraterrestrial life challenges us to expand our horizons, improve our technologies, and confront the profound implications of contact—or the lack thereof.

As we continue to explore the cosmos, the silence we encounter is not merely an absence of noise but a profound mystery that speaks to the very nature of life, intelligence, and the future of humanity. The Fermi Paradox is not just a scientific enigma; it is a reflection of our deepest existential concerns, our hopes, and our fears about the unknown.

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NASA Astronauts Face Extended Stay on ISS Due to Boeing Starliner Issues

 NASA astronauts Butch Wilmore and Sunita Williams
Source : Flickr

                                       

In an unexpected turn of events, two NASA astronauts, Barry "Butch" Wilmore and Sunita Williams, face an extended stay aboard the International Space Station (ISS). Originally scheduled for an eight-day mission, technical challenges with their spacecraft mean they may remain in orbit until early 2025. This development highlights both the complexities of space travel and the rigorous testing required for new space vehicles.

Contents of the Blog:

1. The Boeing Starliner Mission: A Test Flight with a Twist

2. Unplanned Extended Stay: Astronauts' New Reality

3. NASA's Response and Future Plans

4. Longest Space Missions in History

5. About the Boeing Starliner

6. Summary

The Boeing Starliner Mission: A Test Flight with a Twist

On June 5, 2024, veteran astronauts Mr. Wilmore, 61, and Ms. Williams, 58, embarked on a historic journey aboard Boeing's Starliner spacecraft. The mission marked Starliner's first crewed flight to the ISS, a crucial test for evaluating the spacecraft's performance before it is integrated into NASA's regular operations.

The flight was primarily designed to assess Starliner's capabilities, but as it approached the ISS, several issues emerged, notably leaks in its propulsion system and thruster shutdowns. These technical challenges, while manageable during the approach, have raised concerns about the Starliner's ability to safely return the crew to Earth.

 NASA astronauts Butch Wilmore and Sunita Williams in International Space Statiom

Source : Flickr

Unplanned Extended Stay

  

Originally planned as a short-term mission, the astronauts now face the possibility of remaining aboard the ISS until February 2025. One of the solutions being considered is to integrate Wilmore and Williams into a SpaceX Crew Dragon mission scheduled for September. This mission was initially planned to carry four crew members, but it could accommodate the NASA astronauts by leaving two seats empty, ensuring their return in February 2025.

This change would extend their mission duration from eight days to over eight months, a significant adjustment for the astronauts. If this plan proceeds, the Starliner will be returned to Earth without a crew, utilizing computer control to navigate the descent.

NASA's Response and Future Plans

    Space Station Flight Control Room

Source : Flickr

NASA officials are currently evaluating the situation, with a final decision expected within a week. The safety of the astronauts remains the top priority, and the decision will ensure that the best available technology and resources are used for their safe return.

Despite the unexpected extension, NASA assures that Wilmore and Williams are well-prepared to handle the challenges of a prolonged mission. Historically, astronauts have spent much longer periods in space, adapting to the rigors of life aboard the ISS.

Longest Space Missions in History

 Valeri Polyakov 
Source : Creative Commons Wikipedia

While the extended mission may seem daunting, it is not unprecedented. In the mid-1990s, Russian cosmonaut Valeri Polyakov spent a record-breaking 437 days aboard the Mir space station. More recently, NASA astronaut Frank Rubio completed a 371-day mission on the ISS, the longest for any American. Additionally, Russian cosmonaut Oleg Kononenko, currently on the ISS, has accumulated over 1,000 days in space across his career.

About the Boeing Starliner

This artist's concept shows Boeing’s CST-100 Starliner spacecraft, docking to the International Space Station.

                                         

The Boeing Starliner is a next-generation spacecraft designed to transport astronauts to and from the ISS as part of NASA's Commercial Crew Program. Developed in collaboration with NASA, the Starliner aims to provide a reliable and reusable option for crew transportation. Equipped with advanced avionics, safety systems, and a robust propulsion system, the Starliner is a critical component of NASA's strategy to ensure access to low Earth orbit.

Despite the current challenges, Boeing and NASA are committed to addressing the issues and enhancing the spacecraft's reliability. The lessons learned from this mission will contribute to the ongoing development and improvement of the Starliner program, ensuring its future success in supporting NASA's space exploration goals.

Summary

International Space Station : This is where the astronauts Sunita Williams ans Barry Wilmore are present today

Source : Flickr

NASA astronauts Barry "Butch" Wilmore and Suni Williams, originally on an eight-day mission aboard the Boeing Starliner spacecraft, are facing an extended stay on the International Space Station (ISS) due to technical issues with the Starliner's propulsion system. Launched on June 5, 2024, the mission was the first crewed test flight of the Starliner, designed to evaluate its performance for future NASA operations. With leaks and thruster shutdowns preventing the Starliner's safe return, NASA is considering using a SpaceX Crew Dragon mission in September to bring the astronauts back by February 2025. This extension underscores the challenges and complexities of space travel, as well as the rigorous testing required for new spacecraft. Despite the unexpected duration, the astronauts are prepared for the extended mission, drawing on historical precedents of long-term space missions, such as those by Valeri Polyakov and Frank Rubio. The situation highlights the importance of safety and adaptability in NASA's ongoing exploration efforts.

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Unveiling the Radio Universe: A Recap of the 13th Lewis Elton Lecture

 

The School of Maths & Physics, University of Surrey successfully hosted the 13th Lewis Elton Lecture on Thursday, May 2nd, 2024, at the Austin Pearce 3 (AP3) Lecture Theatre in Guildford. The event, titled "Down to Earth Astronomy: A tour of the radio universe," captivated the audience with a journey through the unseen wonders of the cosmos unveiled by radio waves.

A Warm Welcome and Introduction

The evening commenced with a welcoming address by Professor Jim Al Khalili. He offered a warm introduction to the Lewis Elton lecture series and the esteemed speaker, Dr. Emma Chapman for the evening.

A Glimpse Beyond the Visible with JWST

The session then embarked on a captivating exploration, beginning with a dive into the universe using the James Webb Space Telescope (JWST). The discussion delved into the recent launch of JWST, its intricate structure, and the groundbreaking science it has already yielded. The audience was treated to a visual presentation showcasing JWST's stunning images, including those of Jupiter, a Seyfert galaxy, deep field image of the universe and the breathtaking Carina Nebula.

Shifting Gears: The Power of Radio Astronomy

Following this celestial exploration using infrared light, the lecture transitioned to the unseen realm of radio waves. The speaker expertly contrasted radio astronomy with the capabilities of JWST (operating in the infrared) and Hubble (focusing on the visible spectrum). This highlighted the unique power of radio waves to pierce through dust and gas, revealing hidden aspects of the universe invisible to other telescopes. The inherent differences between radio astronomy and its space-based counterparts were further emphasized. Unlike the cleanroom environments associated with JWST and Hubble, radio astronomy is a grounded endeavor. Radio telescopes, often colossal in size, reside in remote desert locations, demanding a unique approach to research and observation.

A Universe Unveiled: Radio Astronomy vs. Infrared/Visible Light

The lecture then delved deeper into the contrasting capabilities of radio astronomy compared to infrared and visible light observations. Here's a breakdown of the key differences:

• Wavelength: Radio waves have much longer wavelengths compared to infrared and visible light. This allows them to bypass dust and gas clouds that would otherwise obscure our view in the optical and infrared spectrums.
• Penetrating Power: Due to their longer wavelengths, radio waves can penetrate deep into interstellar dust clouds, revealing the hidden nurseries of stars and newborn stellar objects. Visible and infrared light, on the other hand, are often blocked by these clouds.
• Unique Phenomena: Radio astronomy allows us to observe phenomena invisible at other wavelengths. This includes the study of pulsars, the remnants of massive stars, and the detection of neutral hydrogen gas, the most abundant element in the universe.

 

A Glimpse into the Future: The Square Kilometre Array (SKA)

As the lecture progressed, the discussion shifted towards the future of radio astronomy. The upcoming construction of the Square Kilometre Array (SKA) captured the audience's imagination. The SKA will be a game-changer, poised to be the largest radio telescope ever built. This behemoth will consist of two arrays, one in South Africa and another in Australia, working in tandem to collect radio waves from space.

The Promise of the SKA

The SKA's immense collecting area, spread across vast distances, will provide unprecedented sensitivity and resolution. This will enable astronomers to:

• Peer further back in time, potentially observing the very first stars and galaxies that emerged after the Big Bang.
• Study the formation and evolution of galaxies in much greater detail.
• Search for new pulsars and other exotic objects in the universe.
• Hunt for potential signs of extraterrestrial intelligence by looking for techno signatures in radio waves.

The SKA promises to revolutionise our understanding of the universe, and the lecture concluded with a call to action, urging the audience to embrace the possibilities of listening to the universe through this revolutionary instrument.

 

 

A Night of Learning and Inspiration

The 13th Lewis Elton Lecture proved to be a resounding success. The pre-lecture drinks reception fostered a welcoming atmosphere for attendees to connect and engage in scientific discussions. The captivating lecture itself sparked curiosity and ignited a passion for exploring the unseen wonders of the universe using the power of radio waves. As the School of Maths & Physics looks towards future events, the 13th Lewis Elton Lecture undoubtedly sets a high bar for scientific discourse and public engagement.

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