The Nature of the Universe, Time Travel and More...

[Will The Serious]

...black holes themselves tend to emit gravitational waves, which are ripples in the fabric of space-time. Astronomers have already detected gravitational waves emitted by merging black holes, but the complex interactions between solitary black holes and their environments can also lead to wave emission.

OK, gravity wave emission.

Two objects of mass fall towards each other. If this is due to the masses involved distorting space-time, a wave may be an apt description of those d distortions. However, a wave implies a directed movement of energy. In a 3+ Dimensional medium, the only type of wave I know of is a compression wave. A radiant series of compressed/stretched instances of the medium moving in one direction. To use the 2-dimensional surface waves on the surface of water is an in adequate analogy.

In the article presented above, it is suggested these waves can focus, perhaps from multiple points of origin, to create an intense beam of energy flow. This is not an outlandish idea at all, we do have, as the article states, a number of examples outside of gravity. The question I want to ask is, what does this beam cause to happen when it interacts with another mass? Does the beam focus an intense falling into the source, far beyond the normal wave effect? Or, might it create a repelling force away from the source? Could it be that the beam represents a gravity well that simply curves space-time towards the beam itself, the way a laser beam may spill light to the sides that allow for a viewer to see the line of the beam?

-Will

 

[Will The Serious]

Life would need to be very hardy to survive on a dust grain as it travels through interstellar space. It would have to avoid hazards like radiation and heat. If life itself couldn't do it, maybe complex molecules that lead to life could. If we grant that it's possible, the next question concerns how quickly it could spread.

https://www.sciencealert.com/life-spreads-across-space-on-tiny-invisible-particles-study-suggests

"It has been shown that, during 5 billion years, the dust grains will reach 105 stellar systems, and by taking the Drake equation into account, it has been shown that the whole galaxy will be full of planetary dust particles," Osmanov explains.

In this article about a paper that hasn't actually been published yet (a little premature to post on ScienceAlert.com, but probably not unusual for this site) the author speculates about the dissemination of the basic origins of life being spread throughout the galaxy much earlier then its examples found here on Earth.

just as the article's author suggests, we are all familiar with this concept from various scifi stories. The problem I see with the paper's basic calculations is that it treats these particles of life, evolved so early in the development of the galaxy itself, as a contiguous, or continuum of material that is plentiful enough to fill a galaxy. To suggest that enough material has evolved from such a limited source as a relatively few viable early star systems that would then be bombarded with the colliding matter that then disperses them throughout the galaxy, ignores the limitations in conditions, material, and time.

If enough building blocks of life can evolve that early in the Galactic life cycle that it can then cover the galaxy's Habitable Zone with these particles, it seems to me that it would be even more reasonable to suggest that life develops easily when given the conditions of star systems in this Habitable Zone, that independent evolution is more likely to be the case.

On the other hand, why not expect pockets of life to have single origins across neighboring stars where the time and conditions allow for a scattered few instances of cosmic dispersion?

If the conditions are right for the proliferation of such transplanted life, it would certainly be ripe for its own life to evolve independently. Probably well before the floating space seeds ever reach the new planet.

-Will

 

[Verteron]

And now we have…Gravitational lasers?
https://www.livescience.com/space/b...xist-throughout-the-universe-new-paper-claims

Could this be used as propulsion?

There is still no way to create gravity apart from having mass, so unless you want to tow a singularity around at the heart of your starship, I wouldn't get too excited.

And as easy as the Romulans make it look, their cupboard-sized singularities are not realistic - something that size would have the mass of several hundred Earth-sized planets.

 

[Asbo Zaprudder]

Just for reference, a one Earth mass black hole has a Schwarzschild radius of 0.887 cm and the radius is directly proportional to the mass.

The simplest gravitational analogue of a laser, a gaser, would be single pass, like a natural maser. Emission from a laser or maser is stimulated and monochromatic, having the frequency corresponding to the energy difference between two energy levels in the gain medium which has been pumped into a non-thermal population distribution. For a gravitational version, I assume you'd somehow have to excite the black holes by spinning them up or dumping electric charge into them. You'd need at least two black holes (or other suitably large masses) as a gravitational field is spin-2, which exhibits an oscillating quadrupole term, whereas the EM field is spin-1 with an oscillating dipole term, so while accelerating a single electron is sufficient to generate EM waves (the quanta being photons), shaking or rotating a single spherically or rotationally symmetric mass does not generate gravitational waves. We don't know whether the assumed quanta of gravity, gravitons, actually exist. Some theorists such as Jonathan Oppenheim posit that they don't.

Physics - Might There Be No Quantum Gravity After All? (aps.org)

Naturally occurring masers do not possess the resonant cavity of terrestrial laboratory lasers and masers. There is only a single pass through the gain medium and so the emission does not have the spatial coherence and modal purity of a human-created laser or maser. Engineering a suitable resonant cavity would be difficult for a gaser, but not impossible, apparently.

Gravity laser - Wikipedia

 

[XCV330]

There is still no way to create gravity apart from having mass, so unless you want to tow a singularity around at the heart of your starship, I wouldn't get too excited.

And as easy as the Romulans make it look, their cupboard-sized singularities are not realistic - something that size would have the mass of several hundred Earth-sized planets.

The advantage of smaller mass black holes is also that they will dissipate more quickly. No need for a gravity laser to make use of it as a power source.

Just hypothesizing, suppose you had a space-fairing civilization with the power to make small black holes, say powerful lasters or hydrogen weaoons to implode meteoric iron into small spinning black holes, setting it on an initial trajectory close to a large starship that will fly behind it it. The black hole acts as a kind of gravity tractor, while at the same time the ship uses the Penrose effect by injecting mass into the small black hole's ergosphere to provide power to its systems, as well as would be needed for the deceleration phase of the journey when the ship arrives near its destination star.

The starship itself could be an asteroid, say of 10km across or so.
The starship could be using this power achieved from the Penrose effect (at near 20% efficiency) to be converting the asteroid into living space, and future settlement features for the time when the crew approach the destination. Life would be quite good on the journey. Enough spin would need to be saved for the deceleraiton, when the power from deceleration of the black hole could be use to send ejecta counter to the current momentum and slow acceleration into a desired solar orbit for what is left of the astroid, now looking more like a space settlement.

 

[Asbo Zaprudder]

I'm guessing all that is quite some way off if the human race ever makes it to Kardashev type III.

 

[XCV330]

I'm guessing all that is quite some way off if the human race ever makes it to Kardashev type III.

yes, fun to imagine but that's about all. But sometimes it is uplifting to me to imagine that if something of us continues into the future, we have options

 

[Asbo Zaprudder]

If we ever become a star-faring race, I imagine we will have merged with AIs as uploaded consciousnesses and be effectively immortal. Flesh and blood substrate humans would have been left far behind. That is, if the AIs decide to keep us around. If Roger Penrose is correct, there might be aspects of human cognition that machines cannot emulate. I think he's wrong - we are just biochemical machines - but there's no way I'm clever enough to demolish his arguments. If quantum processes underly consciousness, I expect we'll find a way to exploit those just as natural selection did.

 

[publiusr]

All shades of Colin Kapp's Chaos Weapon.

 

[Asbo Zaprudder]

Several SF writers have described gaser-based weapons. The Wikipedia article has a brief list. The Inhibitors in Alastair Reynold's Revelation Space series deploy one to disrupt a star. Observing a star exploding unexpectedly might be a signature that such technology exists for real. Hundreds of stars seem to have disappeared inexplicably from our Galaxy over several decades. Hidden by Dyson swarms/spheres, phase shifted out of our reality, no longer exist in our current branch of the multiverse, destroyed by some other exotic device - who knows?

 

[Will The Serious]

Perhaps those stars have exceeded the speed of light, thereby transforming into something completely undetectable. Even their gravity signatures would not be able to keep up. Just more mystery we can write off as Dark Matter.

-Will

 

[Asbo Zaprudder]

Or the Flying Spaghetti Monster has touched them with His Noodly Appendage.

 

[Will The Serious]

If so, they may have been pirate stars.

 

[Asbo Zaprudder]

If so, they may have been pirate stars.

I be thinking those'd be late G to early K-type carbon-rich stars with the classification C-R. The old classification was R, matey.

Great for making a stellar carbonara sauce, says the FSM.

 

[Will The Serious]

The Flying Spaghetti Monster works in mysterious ways.

-Will

 

[Asbo Zaprudder]

The Flying Spaghetti Monster works in mysterious ways.

-Will

His dishes to unfold. So say all Pastafarians.

 

[Asbo Zaprudder]

A really good explanation of Roy Kerr's arguments against the validity of the Penrose Singularity Theorem's prediction of null geodesic incompleteness (that is, being bounded by a singularity) and in favour of singularities not existing in any meaningful sense for real black holes that likely all possess angular momentum.

 

[Asbo Zaprudder]

An interesting video by Sabine Hossenfelder on a new take on dark energy possibly being a manifestation of non-conservation of energy.

I'm sceptical unless it can predict something that no alternative explanation can. Energy conservation is a hard thing to square with the expansion of spacetime as John Baez explained in his blog a few years ago.

The Cosmic Background Radiation (CBR) has red-shifted over thousands of millions of years. Each photon gets redder and redder. What happens to this energy? Cosmologists model the expanding universe with Friedmann-Robertson-Walker (FRW) spacetimes. (The familiar "expanding balloon speckled with galaxies" belongs to this class of models.) The FRW spacetimes are neither static nor asymptotically flat. Those who harbor no qualms about pseudo-tensors will say that radiant energy becomes gravitational energy. Others will say that the energy is simply lost.

Is Energy Conserved in General Relativity? (ucr.edu)

 

[Will The Serious]

Expansion of the universe leading to cosmological redshift...
Are we to understand that red shifted photons have less energy than blue shifted photons?

If you look at the universe from an information point of view, then we could draw an analog to switches and states. The switches are there. The states of those switches can change the information, but the presence of one piece of information or another (state of the switches) does not change the energy in the universe of switches. The presence of energy would only be indicated by the changes in the switch states. The more energy, the more the switches change their state, or vice-versa. Without the switches, there would be no energy, and without their ability to change their state, there would be no expression or detection of that energy.

Does not the color shift of photons merely represent a state of the photon with the same energy?

-Will

 

[Asbo Zaprudder]

Are we to understand that red shifted photons have less energy than blue shifted photons?

Yes, the energy E of a photon is Planck's constant h times its frequency ν, so E = hν.

Does not the color shift of photons merely represent a state of the photon with the same energy?

No.

ETA: If one wants physicists to discuss one's ideas and take them seriously, they need to be backed up by mathematics and they need to offer falsifiable predictions that differ from current theory. The more a theory seeks to overturn established theory, the more effort is required. I suspect QED, the Standard Model and String theory are all convoluted approximations that happen to describe observations in particle physics to varying degrees of success, depending on the number of free parameters, but they might well turn out to be no more valid than the epicycles of the Ptolemaic and Copernican models of the Solar System. It might be that computational irreducibility means that approximations are the best we can do to describe reality and there is no neat equation or sets of equations to do the job.