You would need to capture the ENTIRE energy output of the sun for about 5 years to generate that much energy.

If you can do that, terraforming Mars is nothing, you could just grab a bunch of nearby asteroids or a planet or two and combine.

And just think about how much material you need in order to build a collector large enough to entirely encompass the sun - it's WAY WAY WAY larger than your added Mars mass.

Also you would need a magical strength material just to hold those lightspeed objects in place (think of the huge centrifugal force they are generating). There's nothing in the world that could hold them in place.

I assume they are charged - or how are they keeping them in their "track"? No physical material could handle it. So they have to be charged, well the Synchrotron radiation generated would be enough to sterilize anything nearby.

So "known physics" is a bit of a stretch.......... :)

Story whise there is a caste of underground dwelling engineers who rarely venture to the surface who are taking care of that - via a giant pipe organ like musical instrument/control console!

They effectively play the whole planet using their inner understanding of the system and perfect musical hearing, keeping everything in perfect balance and harmony.

(There are actually some other "engineer castes" such as the Salamanders that live on the floating islands and keep the ppanet warm. They are much less baddass but still rather hot blooded for some reason.)

Not practical at all, but an unusual idea for sure.

My favorite thing about this is that it's completely irrelevant to the show. It's a healing-type show about the daily life of a gondola driver. It could have taken place in actual Venice with no real changes.

Is this really how objects interact with the environment? I am aware of what it means to speed up such an object, as you approach c you need more and more energy, it "feels" as your mass is increasing. What surprises me is that this effect would extend to objects outside?

This seems surprising to me. By the same logic, if an object moved at speed of light it would have infinite mass and unless gravity is not proportional to mass, you would have infinite gravity.

Hence it is impossible for an object (with mass) to reach c.

Only progressively closer - 0.99c, 0.999c, 0.9999c etc.

It's impossible yes, but does it generate a gravitational field?

Yes it does!

Gravity is generated by energy, and mass is just one type of energy. For example photons produce a gravitational field of their own, and are influenced by gravitational fields.

So yes, energy in the form of velocity does produce gravity.

It can get complicated to calculate though, because velocity in the same direction as the observer doesn't exist, only in other directions (including perpendicular).

A thought experiment: Two huge identical masses are traveling toward each other, and perpendicular to an observer. They collide and "stick" to each other. All their velocity is now rest energy, which obviously has gravity.

But this means that even before they collided they also had gravity (since you can never create or destroy gravity, only move it).

Now rotate the experiment - one mass is traveling toward the observer, and the other is traveling with the observer. This time when they collide part of it is rest energy, and the rest is kinetic (since the observer is still moving, while the two objects stopped each other dead still at a point in space).

But this time, the mass that was with the observer had zero gravity (from the POV of the observer), but the mass traveling toward the observer had more gravity.

But it means that gravity is not a "global" phenomenon, it depends on your POV. And that makes for some difficult calculations if you must account for multiple objects all moving. (For example in cosmology. From my understanding the calculations are so complicated that they are mostly just ignored because few objects are moving fast enough for it to matter.)

Thank you for the answer. I am humbled. I have decent understanding of Newtonian physics, but when it goes to relativistic levels I am out of my depth.

Fascinating stuff. So effectively, with "infinite energy" and "unbreakable materials" we could have artificial gravity.

Artificial gravity implies you could turn it on and off. But you can't - if you have infinite energy, you also have infinite gravity, the two are bound together.

Whenever you have energy, you have gravity. I suppose you could send the energy from elsewhere, then send it back when you don't want the gravity anymore.

There's no "generating" gravity. Energy is Mass. They didn't pack atoms, they packed energy, but it is the same stuff.

Firefly also included gravity in terraforming:

All those moons - just like the central planets, they're as close to Earth-That-Was as we could make 'em: gravity, atmosphere, and such

but never provided any explanation. In that medium (live-action TV) it's just handwaving around the production difficulties of showing low-G; Joss by his own admission will cry if you ask him science questions.

While I loved the show, the science was particularly bad.

For example, in the pilot episode, they pass by a Reaver ship while enroute to another planet. The encounter occurs slowly enough for the crew to get a long look at the Reaver ship as it passes. The closing speed seemed to be about 100mph at best.

Whereas with the Apollo mission to the moon, the capsule was traveling 25,000 mph, or ten times the speed of a bullet. And even then it took three days to get to the moon.

And even 25k mph is slow if we're talking about crossing actual interplanetary distances.

Yeah, Joss 'fesses up to that one in the episode commentary.

I don't know if it's "particularly bad" by the standards of screen SF. No shows do it well, and the vast majority don't even try.

What about The Expanse?

From the little I've seen of it, much better than most but still not great.

There are things like the Epstein drive that is nearly "magic". It is as if you had some device that could do direct matter-energy conversion with 99.999999999999999999999% efficiency.

Beyond that, they do treat maneuvering in space with greater realism that most shows.

I don't really remember enough about that show to comment, but the usual failure mode of Newtonian flight models in visual media is that they're extremely reluctant to depict a ship doing a sustained thrust in the opposite direction to its velocity vector, which should logically be ~50% of its time under thrust. They just don't trust audiences to be able to grok it.

Frontier: Elite II (the 1993 game) was the same; it was pretty hardcore Newtonian, but the autopilot would only use the front-facing thrusters to decelerate, even though the main thrusters were much more powerful. If you were under time pressure and needed an efficient flight plan, you had to do turnover and deceleration manually and by eye.

The Expanse does show deceleration explicitly many times. It's called a flip and burn in the show.

Expanse is really interesting that there is basically just one super science item and thats the Epstein drive (well, if you don't count the near magic the protomolecule does). Everything else is pretty much slightly improved current tech (transparent smartphones, better medical tech, practical implants, advanced life support systems).

One could even say some things aere kess advanced than one would expect - quite a few autonomous weapons, big rotating space colonies (oneil island 3, standfor torus, clarke wheel, etc) or worldhouses. Also no laser/gracer/xaser weapons or long range kinetic energy weapons. And no nuclear bomb pumped lasers.

Ouch, that’s one of those painfully bad ideas that makes it obvious most people lack a basic understanding of physics.

Creating enough mass from energy to hit ~2/3 earths total mass is several orders of magnitude larger than the Death Stars main weapon. And as you point out if basically anything fails all that energy gets released on Mars.

> Ouch, that’s one of those painfully bad ideas that makes it obvious most people lack a basic understanding of physics.

I disagree. That's the fun thing about scifi. As long as your idea could theoretically work (which you seem to agree), you can decide whether the theoretical risks manifest or not, or handwave uninvented solutions to those.

Scifi is about dreaming within our universe beyond our current knowledge or limitations.

At least that's my two cents.

Edit: Not familiar with this specific book, but just in general terms.

> Which you seem to agree

Well no their are a host of issues beyond safety and energy requirements. You’re not going to be able to contain that much virtual mass moving at near light speed. We also don’t know if virtual mass produces gravity, etc etc.

> We also don’t know if virtual mass produces gravity

Yes we do. It does.

Gravity is produced by energy, of which mass is only one type.

Last I checked there was zero experimental support for this.

Unless you have a citation?

See my other post here: https://news.ycombinator.com/item?id=25793668

Basically any other answer would be a violation of a whole bunch of conservation laws. In short: It's easy to convert velocity energy to rest energy, rest energy obviously has gravity, so velocity energy must as well.

The issue as I understand it is neutron stars would form black holes in some reference frames. It really breaks relativity for all forms of energy to produce gravity.

Which is completely ok as long as there is some experimental support.

That's a flaw of the theories of black holes, not relativity.

> It really breaks relativity for all forms of energy to produce gravity.

It does not, quite the opposite: It's a fundamental feature of it.

> Which is completely ok as long as there is some experimental support.

There is no experimental support for black holes either, it breaks physics far less for black holes not to exist. (Note black holes are not the same as super massive objects, which do have experimental support. An event horizon has never been observed, just assumed.)

The existence of black holes is part of the general consensus at this point. It’s fine to suggest they don’t exist, just realize you’re disagreeing with the vast majority of physicists and evidence we have.

I don’t mean this as an appeal to authority, just a suggestion you likely have some fundamental misunderstandings. Especially if you never worked through the actual equations.

> The existence of black holes is part of the general consensus at this point.

Yes it is, but the lack of understanding of black holes is also part of general understanding. Physicists know quite well they don't fully understand what happens in every black hole situation.

> It’s fine to suggest they don’t exist, just realize you’re disagreeing with the vast majority of physicists and evidence we have.

We don't have any evidence, only conjecture and [incomplete] math.

Two things that might prevent black holes: Quark degeneracy pressure (unknown, not even the magnitude is known), and time dilation, which leads to "frozen stars" which hover just before becoming black holes, but never do because that last bit of mass that takes them over the edge takes an infinite time to arrive.

Neither of those two are "fringe" theories mind you, they have both been discussed by prominent theorists (I also get to appeal to authority :)

There is quite a bit of evidence, it’s mostly indirect evidence though.

First, a quark degeneracy pressure is irrelevant for the existence of black holes as they have lower density requirements the larger the event horizon. A large enough uniform density sphere of say styrofoam would form an event horizon.

In terms of evidence, “Frozen stars” don’t match up with the Laser Interferometer Gravitational-Wave Observatory’s observations that suggest a collision between a black hole and a neutron star.

That said, the Messier 87 black hole image is the closest thing to a direct observation we have. It’s possible that some mistakes where made, but many would argue it’s solid evidence on it’s own.

PS: Anyway, I am not suggesting this as some statement from on high. I am saying if most people that take serious time and effort looking into something all come to the same conclusion it’s prudent to dig deep before coming to a different conclusion. That’s especially true of physics where actually understanding the math behind existing models is difficult. Essentially you should be able to point to some math and say see this, this is wrong and then justify that statement.

It's a minor detail of the setting of a story. I doesn't matter if it's practical in real life, it just has to be not be in contradiction with the fictional world of the story. Kind of like Star Trek allowing faster-than-light travel due to imagined discoveries in the fields of physics.

I like hard science fiction that's based in known physics, but I can still enjoy science fiction that's not totally realistic as long as it's at least consistent with itself and doesn't contradict known physics out of pure laziness or ignorance.

I think it's a better solution than just saying "Mars is at full gravity because of magic we won't explain."

The advantage of saying magic we can’t explain is you have fewer uses of other magic we can’t explain. Having that much mass moving near light speed requires absurdly strong materials etc. You need a silly energy source, etc etc.

Similarly, you get a lot of knock on effects from the other hand waves.

it's ok, the engineers learned enough from the previous 3 failures to make sure it really doesn't happen again with this one :)

So the energy they need to bring is the energy equivalent of the matter they would have needed to bring to get the same result.

Or an other way to see it : they have to annihilate two Mars planet to get enough energy to create gravity on the third one.

Yep, pretty much - but tourist from Earth will feel gravity just as at himo and gondola rides will be 100% authentic! ;-)

No wonder Aria is a perfect slice of life / healing series - any aggressive aliens or other evildoers don't stand a chance agains their rather low profile yet insanely high tech level! :)

BLAME! Could be an example of megastructures gone haywire.

I still remeber that one episode when the main character goes up a stairwell for quite a while (possibly weeks+) then finally reaches the top, opens a manhole cover basically, enetering a huge room - for one he can't see the ceiling and it goes in all directions and seems flat.

After wandering around for an unspecified while he encounters a cyborg scientist looking through some sort of instrument. He tells him this "room" in the megastructure is a spehrical empty space and has the inner diameter of Jupiter.

So if you ever wondered where to Von Neumann construction bots that got a little haywire got all the raw materials...

Huh, that's clever and terrifying.