The dream of exploring the cosmos beyond our solar system has captivated the imagination of scientists, visionaries, and space enthusiasts for decades. However, the vast distances and limitations of traditional rocket propulsion have posed significant challenges to interstellar travel. Enter quantum propulsion and its revolutionary concept of light-thrust engines, offering the potential to propel humanity to the stars and unlock the secrets of the universe. In this blog article, we delve into the fascinating world of quantum propulsion and how light-thrust engines could transform the future of space exploration.
Within Newtonian dynamics, inertia is a fundamental property of matter, observed as the resistance of an object to be accelerated (an object will remain at constant velocity unless acted upon by an external force). This is also known as the inertial mass of an object, and is equivalent to the gravitational mass. Within Newtonian dynamics, it is simply a given property, and there is no explanation for its source, like many other free parameters of the Standard Model.
Quantum Propulsion: A New Paradigm
Quantum propulsion is a cutting-edge concept that marries the principles of quantum mechanics with space propulsion. At its core lies the concept of quantized inertia, which proposes that an accelerated observer in a vacuum experiences Unruh radiation. Harnessing this quantum effect, scientists envision light-thrust engines that can achieve continuous acceleration without the need for conventional propellant.
Quantized Inertia (QI) is a theoretical framework proposed by physicist Mike McCulloch to explain the phenomenon of inertia. Inertia is the resistance of an object to changes in its motion, and according to QI, it arises from the way that information is lost when an object accelerates.
In the QI framework, the vacuum of space is assumed to contain a “thermal bath” of virtual particles, known as the Unruh radiation. When an object accelerates, it experiences a decrease in the amount of Unruh radiation that it can detect, which causes a loss of information. This loss of information, in turn, leads to the object experiencing a force in the opposite direction to its acceleration, which manifests as the phenomenon of inertia.
There is a theoretical prediction that accelerating objects will observe thermal radiation from the vacuum where observers at rest relative to the accelerating frame will not observe such thermal emission from the vacuum. This is known as Unruh radiation, and is a sister effect to Hawking radiation, in which black holes thermalize.
Unruh radiation has never been observed, but it appears in quantum physics. In quantum theory, empty space can be described as being filled with a quantum field. A vacuum, in this view, is simply the lowest possible energy state for these fields. In most cases empty space looks like a vacuum as we’d expect, but for an accelerating observer the field has an observed energy. As a result, an accelerating observer would be heated by quantum particles known as Unruh radiation. McCulloch argues that when an object accelerates it interacts with Unruh radiation, which causes the object to resist a change of motion. Thus inertia is an effect of acceleration rather than an inherent property of matter.
QI also predicts a minimum amount of acceleration, known as the “Unruh temperature,” below which an object cannot detect the Unruh radiation and therefore does not experience inertia. This minimum acceleration is related to the Planck constant and the speed of light, and is incredibly small, making it difficult to observe experimentally.
The Unruh effect in standard quantum theory is extraordinarily small. If you accelerated a trillion times greater than Earth gravity, you’d only see a thermal temperature of 40 billionths of a degree above absolute zero. Furthermore, since Unruh radiation comes from all directions, it couldn’t create the effects of inertia on its own
In addition to explaining the phenomenon of inertia, QI also makes predictions about the behavior of other physical systems. For example, QI predicts a modification of Newton’s second law at extremely small accelerations, and it also predicts a modification of the gravitational force law at very large distances. These predictions have yet to be tested experimentally.
But rather than be deterred by this, McCulloch adds other effects into the mix. Since the observable universe is finite, the wavelengths of Unruh radiation is limited, and combined with a cosmic Casimir effect and a bit of information theory, can somehow produce the effect of inertia .
McCulloch’s theory describes an anisotropic force produced by Unruh radiation around an accelerating object due to a Hubble-scale Casimir effect. In the Casimir effect, a force is produced between two closely spaced parallel plates due to the exclusion of certain wavelengths of zero-point fluctuations in the vacuum between the plates. McCulloch describes a similar type effect experienced by an accelerating object, where the cosmological horizon and a dynamical Riddler horizon act as the “plates” which disallow certain wavelengths of the Unruh radiation behind the accelerating object. There will therefore be a net force from the Unruh radiation opposing the direction of acceleration, effectively creating a resistance to acceleration, or inertia.
Critics of QI argue that the framework lacks a solid theoretical foundation, and that its predictions have not been fully tested by experiments. Nevertheless, QI remains an active area of research, and its proponents continue to work on developing the theory and testing its predictions.
Overall, QI represents an intriguing and potentially important contribution to our understanding of fundamental physics, and it will be interesting to see how the theory develops in the coming years.
For a deeper understanding on Quantum propulsion theory and applications please visit: Quantum Propulsion: Revolutionizing Space Exploration with Light-Thrust Engines
Continuous Acceleration: The Key to Interstellar Travel
One potential application of QI is in the field of space propulsion. Because QI predicts that there is a minimum acceleration below which an object does not experience inertia, it suggests that it might be possible to create propulsion systems that operate at this minimum acceleration, and therefore do not require the large amounts of energy that conventional propulsion systems do. However, much more research and development is needed before such systems can be created.
McCulloch’s model has been in the works since 2008, but it has become popular in recent years due to its connection to the EMDrive. It is the device that (according to its proponents) can create a thrust without any traditional propellant which could revolutionize space travel and take us to the stars. The EMDrive has created quite a stir among the general public because of the tremendous possibilities if it succeeds. Meanwhile, scientists have noted that even the best experimental results can’t be distinguished from background noise, and that such a device would violate basic physics. McCulloch argued that the effect was not only real, but that it could be explained in the context of his model.
One of the most significant advantages of light-thrust engines is their ability to provide continuous acceleration. Unlike traditional rockets, which require vast amounts of propellant and experience diminishing acceleration over time, light-thrust engines offer sustained thrust, enabling spacecraft to reach unprecedented velocities. This could drastically reduce travel times to distant stars and exoplanetary systems, making interstellar missions within humanity’s grasp.
Efficiency and Sustainability
Quantum propulsion promises higher efficiency and sustainability in space travel. By eliminating the need for large propellant reserves, light-thrust engines allow for increased payload capacity, supporting more sophisticated scientific instruments, and extended exploration missions.
Advancements in Quantum Engineering
Quantum engineering is at the heart of light-thrust engines’ development. Researchers are exploring advanced control techniques, error correction protocols, and quantum computing to optimize and stabilize the quantum states required for continuous acceleration. Collaborations between physicists, engineers, and computer scientists are paving the way for groundbreaking breakthroughs.
Paving the Way for Crewed Interstellar Missions
Perhaps the most ambitious vision of quantum propulsion is its potential to pave the way for crewed interstellar missions. With continuous acceleration, crewed spacecraft could traverse the immense distances to neighboring star systems, making humanity’s dreams of exploring exoplanets and distant celestial bodies a reality.
Exploring Beyond Our Imagination
Quantum propulsion could lead to the discovery of uncharted territories in the cosmos. Faster travel times and continuous acceleration would enable missions to explore multiple destinations, making it possible to study a diverse array of celestial bodies and phenomena, unlocking new frontiers of scientific knowledge.
Testing Fundamental Physics
Interstellar missions using light-thrust engines offer a unique opportunity to test the foundations of quantum mechanics, relativity, and the nature of space-time. The high velocities and relativistic effects experienced by spacecraft could yield new insights into fundamental physics principles.
The CMB Stage 4 and SPIE experiments are two of the most promising experiments that are being planned or underway to detect the Unruh effect.
The CMB Stage 4 experiment is a collaboration between the National Institute of Standards and Technology (NIST) and the University of California, Berkeley. The experiment is designed to measure the polarization of the cosmic microwave background (CMB) with unprecedented precision. The CMB is a faint afterglow of the Big Bang, and it is thought to be the most perfect isotropic blackbody radiation in the universe.
The Unruh effect could potentially be detected as a small change in the polarization of the CMB. This is because the Unruh effect would cause the vacuum state to be different in different parts of the universe, and this would lead to a small change in the polarization of the CMB.
The SPIE experiment is a collaboration between the University of California, Berkeley and the University of Washington. The experiment is designed to measure the Unruh effect directly by accelerating a test mass and looking for the thermal bath of particles that would be predicted by the Unruh effect.
The SPIE experiment is a very challenging experiment, but it has the potential to be a very sensitive test of the Unruh effect. If the SPIE experiment is successful, it would be a major confirmation of quantum field theory and our understanding of the nature of spacetime.
The First All-Electrical Thruster – the IVO Quantum Drive – is Headed to Space
On June 10th, 2023, an all-electrical propulsion system for satellites (the IVO Quantum Drive) will fly to space for the first time. The system was built by North Dakota-based wireless power company IVO, Ltd., and will serve as a testbed for an alternative theory of inertia that could have applications for propulsion. The engine will launch atop a SpaceX Falcon 9 rocket as part of a dedicated rideshare (Transporter 8) hosted by commercial partner Rogue Space Systems. If the technology is validated, the Quantum Drive could trigger a revolution in commercial space and beyond. And if not, then we can relax knowing that the laws of physics are still the laws of physics!
In 2021, IVO began to develop a new all-electrical propulsion system that leveraged an alternate theory about inertia. Known as the IVO Quantum Drive, this proposed system relies on the theory of Quantized Inertia (QI), a controversial idea that many physicists view as a fringe theory.
If validated, such a system would provide multiple advantages over conventional propellants, the most notable of which is extreme efficiency. According to IVO, a single Quantum Drive can achieve up to 52 millinewtons (mN) of thrust from a single watt of electricity supplied via a combination of onboard power storage and solar power. This would be a considerable improvement over Hall-Effect thrusters (ion engines), which can achieve 25–250 mN of thrust, have lower energy efficiency (65-80%), and require more power – 1–7 kilowatts (kW).
Another benefit, according to IVO, is the modular design of the thruster, which allows multiple units to be stacked (and on multiple axes) to achieve greater thrust and meet the needs of individual spacecraft. On top of that, a typical Hall-Effect thruster will weigh more than 200 kg (440 lbs), while a single external and internal Quantum Drive unit weighs just 186.6 grams and 103.5 grams (6.6 and 3.65 oz), respectively.
As co-founder Telehey, now the Chief Operating Officer of IVO Ltd., told Universe Today via email: “The IVO Quantum Drive really is a total departure from the current limitations of modern space propulsion. It is the first pure electric propulsion device, meaning it requires only electricity to run. Gone are the days of complex fuel systems which require special fuel solutions to propel the spacecraft. As long as we have electricity, we have thrust, which is why unlimited Delta-V is possible for the first time ever. Due to its self-contained nature, this is the first propulsion device that can be completely internal to a spacecraft.”
DARPA invests in propellant-free rocket theory
Physicist Mike McCulloch plans to use a $1.3 million grant from the federal agency DARPA to prove his quantized inertia theory is more than just a spark plug for heady debates on online physics forums. McCulloch believes his ideas about quantized inertia and Unruh radiation can inspire the creation of a rocket engine that turns light into thrust without the assistance of a chemical propellant.
Chemical rockets are very expensive because of the explosive propellant they need, so this new kind of thruster would be much cheaper and safer as it would only need a source of electrical power to accelerate the core of a thruster. The research is being funded through DARPA’s Nascent Light-Matter Interactions (NLM) programme, which aims to improve the fundamental understanding of how to control the interaction of light and engineered materials.
Engineers at DARPA, the Defense Advanced Research Projects Agency, think McCulloch might be onto something. “There is increasing global activity in space,” Mike Fiddy, program manager for the Nascent Light-Matter Interactions program in DARPA’s Defense Sciences Office, told UPI. “DARPA is seeking to deepen our understanding of how to move objects around in more energy efficient and versatile ways.”
McCulloch thinks imbalances in Unruh radiation can be used to generate a more energy efficient thrust. “Uhler radiation is a kind of radiation that you see when you accelerate,” McCulloch, a professor of physics at the University of Plymouth in England, told UPI. “When you accelerate, a horizon radiation appears behind you, and the radiation emanates from this horizon the way Hawking radiation is emitted by the horizon of a black hole.”
“One definition of quantized inertia is that the force we know as inertia is caused by a gradient in this Uhler radiation,” he said.In previously published papers, McCulloch has used his quantized inertia theory to explain galaxy rotation without the presence of dark matter, as well as the thrust achieved by the EmDrive.
The EmDrive was NASA’s attempt at developing a propellant-less rocket engine. According to the EmDrive’s inventors, the engine musters up a bit of thrust by bouncing microwaves from one end to the other of an unevenly-shaped container, creating a difference in radiation pressure and generating drive — although a study earlier this year questioned whether it worked at all.
“I believe that the EmDrive is a manifestation of quantized inertia,” McCulloch said. He said a different set of experiments may produce more powerful QI-powered thrusts.
Before the DARPA grant, announced this month, is used to build experiments, it will fund more theorizing. “The first thing the money will allow me to do is hire a postdoc,” McCulloch said. With the help of a postdoctoral researcher, McCulloch plans on building out and filling in his quantized inertia theory. “We’re going to try to develop a numerical model to make the theory fully predictive,” he said.
After 18 months of theory-building, the grant will help fund experimental teams in Germany and Spain, which will build a pair of thrust-producing experiments. “One such experiment is a shielded laser loop, and another uses asymmetrical mirrors and laser light,” McCulloch said.
If the experiments succeed, as predicted by McCulloch’s theory, researchers will look for ways to enhance the thrusts. Throughout the different phases of research, McColloch hopes to continue to use his ideas to explain and understand observable astronomical data.
“I think that the strength of the theory is that it explains a lot of things on different scales — both at the cosmological level and the level of the laboratory,” he said.
McCulloch’s theory purports to explain cosmological phenomena more accurately than the Standard Model, which relies on the existence of dark matter. Coincidentally or not, he’s faced pushback from some physicists. “I have gotten a lot of resistance from people who believe in dark matter,” McCulloch said. “They don’t like it at all, as many scientists and universities receive a lot of money to build expensive machines looking for the stuff.”
But even if mainstream physicists are reluctant to engage with McCulloch’s ideas, DARPA was interested enough to open the coffers. They might be willing to do so again, should the right idea come along.
“The broad interest in understanding more about how electromagnetic waves and matter interact will continue to stimulate new hypotheses and theories,” Fiddy said. “When these new ideas are relevant to DARPA’s mission and are testable, the agency may well support them.”
Quantum propulsion and light-thrust engines represent a visionary leap in space exploration, promising to revolutionize our understanding of the universe and our place in it. As research and engineering in quantum propulsion continue to progress, we are on the cusp of transforming science fiction into science fact. With continuous acceleration and sustainable propulsion, humanity is poised to venture beyond our solar system and explore the mysteries of the cosmos like never before. The future of space exploration with light-thrust engines is bright, and as we venture forth, we may discover that the stars are no longer out of reach.