13

Your photon cage already gives you the most efficient thruster possible: a photon rocket. Photons carry momentum (that's how lightsails work) so you simply open a hole in the photon cage and the outflow of photons creates thrust in the opposite direction. Specific efficiency depends on the mass of your photon cages and energy of the photons stored but if ...


9

If there's no laser at the target you have decelerate on your launch beam. This can be done if you can manipulate things precisely enough--when it's time to stop you cut a ring off your sail, it goes on ahead and you flip your spacecraft. Note that the discarded ring must be the majority of the mass of your spacecraft as well as the majority of your sail! ...


7

This is another case where the square-cube law comes into play: the mass of the hanging gecko scales up with the cube of the length, while the contact area which ensures the gecko is sticking to the surface only grows with the square of that length. $M \approx l^3$ $S \approx l^2$ If we take for good your figure each of a gecko's four feet has a clinging ...


7

Electric fish don't fry themselves because their discharge lasts no longer than three milliseconds. Source for the pulse duration: section III of this article about using electric eels to power lamps, because science! Seriously. Those guys even put this nice little graph about what they intend to do, I don't now why they didn't get the IgNobel in 2014: ...


7

Normal mains-voltage (240/110 volts) is easily sufficient to cause a shock, that's unpleasant and potentially somewhat dangerous, but because of the resistance of skin which can be anywhere between 5KOhms to several million Ohms, the current flow is usually insufficient to cause any tissue damage. The skin's insulating ability is the body's greatest ...


6

Without suspended particles like sand, no amount of wind will do this. It is far more likely that a person subjected to such winds would be lifted into the air, or, if secured to the ground, ripped apart. Truth be told, even that is extremely unlikely; while we have records on how much force it takes to tear off a limb, for example, that is based on medieval ...


5

Use the laser highway system to both accelerate and decelerate your spacecraft The yellow arrows represent the laser light coming from the origin star system (the one with the laser infrastructure). The red arrows represent the laser light bounced back off the blue detached light sail, onto the pink light sail attached aft of your spacecraft. The pink sail ...


5

Frame challenge you need powered tags so use Phone ID or RFID implant There is a limit to the amount of radio energy you can subject a human body to, and passive tags need far more energy than that to work at hundreds of meters. So you really need active AKA powered tags. We could do it today if you are willing to spend enough money, what you need is ...


5

Capacity matters less than max voltage does As a former electronics hobbyist and electronic component collector, I can say from experience that much smaller capacitors can be quite dangerous, because they are suitable for high voltages. Even with normal consumer elco capacitors, like the the ones used in back in the 60's for TV power supplies. Capacity of ...


4

If we mix and match wireless tech - 100m with passive RFID is possible. Johns well researched answer covers all of the basics and I'm not going to duplicate his work or references (as hard-science doesnt forbid building on other answers), but he shows: Passive RFID (no battery in the card) can transmit 10m. Active RFID (where the card has a tiny little ...


3

You can make a decent approximation of the surface pressure $p_0$ of a planet just knowing its mass $M$, radius $R$ and atmospheric mass $M_{\text{atm}}$: $$M_{\text{atm}}=\frac{p_0}{g}4\pi R^2=\frac{4\pi R^4p_0}{GM}\implies p_0=\frac{GMM_{\text{atm}}}{4\pi R^4}$$ Therefore, we can split your work in half and just ask what the mass of the atmosphere will be ...


1

To add to the technical discussion, perisens.de/wp-content/uploads/2018/09/publication2011_RFIDSystech.pdf has an analysis of attempting to extend the range of standard credit card RFID tags. The conclusion was that with special transmitters and antennas, the tags could be read up to several meters, but to go further required huge equipment. A more reliable ...


1

You don't have to have a photon cage at all. So, say we have a starship en route to an uninhabited system. It was propelled to about 0.5C by a stellar laser back in a nearby frontier system, and has been traveling for a few centuries now. I have been trying to figure out a way for this ship to decelerate at its destination, and have tried to avoid having it ...


1

Radiation shielding 101 Radiation is everywhere, not only around Jupiter. We only start caring about if if the energy levels get too high. There is electro magnetic radiation that is very energy intensive per photon (UV, X-ray and Gamma) the issue here is that, unlike with longer wavelength light, the photons don't just move or exite electrons, but can push ...


1

Increase the starting density of dark matter. From OP: The parameters I'm willing to change are the various density parameters for photons, baryonic matter, dark matter, and dark energy: Ωγ, ΩM, ΩD, and ΩΛ. From OP: Given what I know about star formation in the early universe (see e.g. 1 2, for more information), I think we can break the process down into ...


Only top voted, non community-wiki answers of a minimum length are eligible