Tag: physics

Interstellar

Multi-Generation Space Ships

the motivations, technology, and prospects for interstellar flight, while the balance deals with anthropological, genetic, and linguistic issues in crew composition for a notional mission with a crew of 200 with a flight time of 2 centuries.

2007-06-15: On the infeasibility of interstellar travel

We require the equivalent energy output to 400 megatons of nuclear armageddon in order to move a capsule of the gross weight of a fully loaded Volvo V70 automobile to Proxima Centauri in less than a human lifetime. That’s the same as the yield of the entire US Minuteman III ICBM force. Our entire planetary economy runs on 4TW. So it would take our total planetary electricity production for a period of 5 days to supply the necessary va-va-voom.

2009-02-01: Tau Zero Foundation

The Tau Zero Foundation is a volunteer group of scientists, engineers, entrepreneurs, and writers who have agreed to work together toward practical interstellar flight and to use this quest to teach you about science, technology, and our place in the universe.

2010-05-07: Project Icarus

To design a credible interstellar probe that is a concept design for a potential mission in the coming centuries.

2011-01-06: No Interstellar Travel Before 2200. About 10^18 Joules required, more than a Kardashev type I civilization.
2011-05-20: Star Children. It might make sense to start a religion to ensure long term space travelers retain their goals.

We are seeking ideas for an organization, business model and approach appropriate for a self-sustaining investment vehicle. The respondent must focus on flexible yet robust mechanisms by which an endowment can be created and sustained, wholly devoid of government subsidy or control, and by which worthwhile undertakings—in the sciences, engineering, humanities, or the arts—may be awarded in pursuit of the vision of interstellar flight

2013-04-25: Starship Century

Is this the century we begin to build starships?

yes

2014-03-12: Starship Century

Starship Century is a symposium coordinated by the new Arthur C. Clarke Center for Human Imagination in collaboration with Gregory and James Benford, presenting ideas from their anthology of science and science fiction. First 8 minutes most of them agree the era of interstellar starships will be 100-300 years away after there is lot of solar system development.

2015-10-21: Black hole drive

The petawatt Hawking radiation of γ-ray laser-created subatomic black holes (Schwarzschild Kugelblitzes or SKs) has been proposed as a propulsive and power source for interstellar starships. Production of a black hole requires concentration of mass or energy within the corresponding Schwarzschild radius. In familiar 3D gravity, the minimum such energy is 10^19 GeV, which would have to be condensed into a region of approximate size 10^-33 cm. This is far beyond the limits of any current technology; the Large hadron collider (LHC) has a design energy of 14 TeV. This is also beyond the range of known collisions of cosmic rays with Earth’s atmosphere, which reach center of mass energies in the range of 100s of TeV. It is estimated that to collide 2 particles to within a distance of a Planck length with currently achievable magnetic field strengths would require a ring accelerator ~1k light years in diameter to keep the particles on track.

2016-02-20: Interstellar Propulsion. A 100kg robotic craft could be sent to Mars in 3 days with the power levels that large rockets produce (50-100 GW)

2016-04-12: Starshot. This makes me proud of our civilization: We do stuff like this.

Milner wants his $100M to fund research that will culminate in a prototype of a probe that can beam images back to Earth. The images would arrive less than 5 years after the probe reached the star.

There are no official specs yet, but the probe would have a 2-megapixel camera, along with star-finders to help it get its bearings, after it boots up on the approach to Proxima Centauri. The probe will target one of the system’s 2 sunlike stars. It will be aimed at a planet (or planets) in the star’s habitable zone, the temperate region where oceans don’t boil or freeze, but instead flow, nurturing the kind of complex chemistry that is thought to give rise to life.

2018-08-14: Propellantless interstellar travel

Researchers propose a new mode of transport which relies on electric-field moderated momentum exchange with the ionized particles in the interstellar medium. While the application of this mechanism faces significant challenges requiring industrial-scale exploitation of space, the technological roadblocks are minimal, and are perhaps more easily addressed than the issues presented by light sails or particle beam powered craft. This mode of space travel is particularly well suited to energy efficient space travel at velocities less than 5% of light speed, and compares exceptionally well to light sails on an energy expenditure basis. It therefore represents an extremely attractive mode of transport for slow (~multi-century long) voyages carrying heavy payloads to nearby stellar neighbors. This could be very useful in missions that would otherwise be too energy intensive to carry out, such as transporting bulk materials for a future colony around Alpha Cen A, or perhaps a generation ship.

2020-02-21: Interstellar Probe, weighing a few grams, and getting there in 20 years.
2020-09-03: Mach Effect Propulsion. Jim Woodward is investigating mach effect thrusters as part of NASA NIAC. If successful, this will get us to .xc, making humanity interstellar.
2022-08-05: Bow Shock Deceleration

Deceleration at the destination system is a huge problem for starship mission planning. A future crew, human or robotic, could deploy a solar sail to slow down, but a magsail seems better, as its effects kick in earlier on the approach. Looking at the image below, however, suggests another possibility, one using the interactions between stars and the interstellar medium to assist the slowdown. The bow shock produces 3D structures, surfaces within which one can move while shedding speed, perhaps braking via a magsail. Each star would produce its own unique deceleration environment, allowing us to brake where possible along the bow shock, the astropause (cognate to the heliopause) and the termination shock.

E8

after 4 years of intensive collaboration, 18 leading mathematicians and computer scientists from the US and Europe have successfully mapped E8, one of the largest and most complicated structures in mathematics.

math is moving towards high energy physics style collaboration
2007-11-15:

keep in mind that this is just a theory, it has no experimental support, and it might be wrong. I think it’s got a shot, which is why I work on it, but it’s still just a developing theory. So don’t go crazy, people; but yes, it is pretty damn cool. This is an all-or-nothing kind of theory – it’s either going to be exactly right, or spectacularly wrong. I’m the first to admit this is a long shot. But it ain’t over till the LHC sings.

2008-10-14: it’s all about the E8

Fusion

Inertial electrostatic confinement fusion provides a potential breakthrough in designing and implementing practical fusion power plants. This is a $5T / year market.
2007-04-27: inertial confinement is a lot more promising than magnetic confinement. Plus 1000x cheaper to build. This is very very exciting (and a $5t/ year market).
2008-01-15: Fusion power grows more quickly than Moore’s law. It has increased by a factor of 10000 in the last 30 years, and another factor of 6 is required for a power plant. ITER will be 500MW, 10x over the energy threshold.

2011-08-03: Mark Suppes:

I do believe this is the WORLD’S FIRST AMATEUR POLYWELL!!!

Science. It works, bitches. Mark Suppes is one of my heroes. He lives in Brooklyn. His hobby: building his own bussard fusion reactor. He will very likely fail, but what if he succeeds? Here is a nice article on him. If you are behind in your fusion terminology, bussard reactors are an alternative design that doesn’t require 10s of billions to get if off the ground. The best introduction is this tech talk:

2014-04-12: Since the big science / consortium approach hasn’t worked so far, maybe a macgyver approach will.

Ivanov’s story is just one example of the serendipity involved in this small Canadian company’s rise to the forefront of a worldwide race to harness nuclear fusion, a race that has been going on fitfully, consuming $10Bs, for more than 50 years. (All existing reactors operate using nuclear fission, rather than fusion, which is a very different process.) Started in 2002 by a successful corporate scientist in the throes of a midlife crisis, General Fusion has already outlasted past private-sector attempts to commercialize fusion energy. Instead of petering out, it’s garnered the attention and respect of a small but growing cadre of scientists, energy executives and adventurous investors around the world.

2016-08-15: Towards commercial fusion

If LPP is successful with their research and then successful with commercialization they will achieve commercial nuclear fusion at the cost of $400K-1M for a 5 megawatt generator that would produce power for about 0.3 cents per kwh instead of 6 cents per kwh for coal and natural gas. It would be a game changer. Their monthly reports have shown that there are many technical, material and theoretical challenges. LPP has shown a lot of grit and ingenuity to overcome challenges.

2016-11-04: Longer plasma

The Experimental Advanced Superconducting Tokamak (EAST) in Heifi, China was able to sustain plasma in the H-mode confinement regime for 102 seconds.

2019-02-17: Fusion Projects Use Misleading Power Terms

ITER has spent over $14B so far and will only reach some level of plasma energy gain for a few minutes at a time if everything works as planned. The condition of Q = 1, when the power being released by the fusion reactions is equal to the required heating power is called breakeven or scientific breakeven. Plasma breakeven can be 100x away from what is needed for a practical reactor.

As explained by Sabine Hossenfelder:

The Q-plasma also doesn’t take into account that if you want to operate a power plant, the heat that is created by the plasma would still have to be converted into electric energy, and that can only be done with a limited efficiency, optimistically maybe 50%. As a consequence, the Q total is much lower than the Q plasma. If you didn’t know this, you’re not alone. I didn’t know this until a few years ago either. How can such a confusion even happen? I mean, this isn’t rocket science. The total energy that goes into the reactor is more than the energy that goes into the plasma. And yet, science writers and journalists constantly get this wrong. They get the most basic fact wrong on a matter that affects 10s of billions of research funding. The plan is that ITER will generate 500 MegaWatts of fusion power in heat. If we assume a 50% efficiency for converting this heat into electricity, ITER will produce about 250 MegaWatts of electric power. That gives us a Q total of about 0.57. That’s 6% of the normally stated Q plasma of 10. Even optimistically, ITER will still consume 2x the power it generates. What’s with the earlier claim of a Q of 0.67 for the JET experiment? Same thing.

2019-06-27: Commonwealth Fusion Systems

The Reactor Core of Commonwealth Fusion Systems. This Tokamak plasma fusion ring supports the steepest temperature gradient in the solar system (1 million degrees to room temp within 2mm)!

2020-10-01: Venture capital is entering fusion

This third party analysis verifies our investment thesis; tokamak fusion is an engineering project, not a science project. If they can build it, the scientific community agrees on the performance that will result.

2022-05-24: An unwelcome bottleneck, tritium.

The tritium used in fusion experiments like ITER, and the smaller JET tokamak in the UK, comes from a very specific type of nuclear fission reactor called a heavy-water moderated reactor. But many of these reactors are reaching the end of their working life, and there are fewer than 30 left in operation worldwide. 20 in Canada, 4 in South Korea, and 2 in Romania, each producing about 100 grams of tritium a year. But now, with the help of AI-controlled magnets to help confine the fusion reaction, and advances in materials science, some companies are exploring alternatives. TAE Technologies is attempting to build a fusion reactor that uses hydrogen and boron, which it says will be a cleaner and more practical alternative to D-T fusion. It’s aiming to reach a net energy gain—where a fusion reaction creates more power than it consumes—by 2025. Boron can be extracted from seawater by the metric ton, and it has the added benefit of not irradiating the machine as D-T fusion does. It’s a more commercially viable route to scalable fusion power. But the mainstream fusion community is still pinning its hopes on ITER, despite the potential supply problems for its key fuel. “Fusion is really, really difficult, and anything other than deuterium-tritium is going to be 100x more difficult, 100 years from now maybe we can talk about something else.”

Mecca Crowd control

Several of the new measures were controversial, with some experts worrying it would make things worse. But the scheme was a success. An important step was to introduce a one-way system, with roads designated only for walkers coming from the stoning back to the camp. “Last year you had to push a lot to get to the camp. This year you could comfortably follow the stream all the way. Everyone was very happy.”

fluid dynamics to the rescue. granted, the whole thing is pretty stupid anyways