MigL

Say you are looking at a planet orbiting Alpha Centauri, 4.3 light years away. Now assume you have a wormhole connecting the Earth to this planet orbiting Alpha Centauri. Space-time is 'local' at either opening of the wormhole, so if you step through, you emerge on that planet 4.3 years in your future. Not as you were seeing it from Earth.

Pandering to every group, and further sub-dividing society.

That's not really what it says. Time is relative so any superluminal ( spacelike ) travel will be faster compared to regular travel through space-time. That is what a wormhole would allow you to do. And to come back through the wormhole to your original starting point with only your travel time having elapsed. The wormhole, in effect, 'links' two distant regions of space-time and makes them local. The article goes on to explain how the standard model only allows for microscopic wormholes and the tidal effects of intense gravity, but those are not the biggest issues. Keep in mind that what a scientific model allows is not the same as what reality allows. IOW, there is a good chance that wormholes are not realizable.

Interesting ... Is this what Reynolds number indicates ? I always thought t indicated where 'laminar' flow changes to turbulent ( or ratio of inertial to viscous forces in a fluid ). Is this the specific energy interpretation ? Back to supersonic sub design … As John suggests, given enough power, it has to go supersonic; we are just trying to determine ( and mitigate ) resulting effects. I suppose the easiest way is to shoot hi-power bullets into water; at least initially, they would be travelling at 1500m/s. Never actually done this, but seen video of ( slower ) bullets travelling through water, and they do leave a vapor trail. Heat and pressure energy are quickly attenuated by the surrounding medium. Unlike a sonic boom, water is a good heat sink, and expansion takes care of the vapor pressure.

I'm thinking that once the sub got to supersonic under water ( 1500 m/s ), the shock cone would actually become a vapor cone, with liquid water on the outside of the cone, and an immediate change to vapor inside the cone, due to vastly decreased pressure. The cavitation wouldn't be behind the sub, but behind the shock cone and all around the sub. That would really make it interesting. You often see jets with moisture condensation inside their shock cone due to decreased pressure … ( the shock starts at subsonic speeds at 1/4 chord because local airflow, at the wing, is supersonic ) Looking forward to other members' input, and corrections.

There are two types of fluid flows in aero/hydrodynamics, compressible and incompressible. They can both be modelled by little springs between each fluid particle; when you push against one particle, it pushes against the next via the little interconnecting springs, and the fluid, in effect, compresses. If you push too fast, the little springs reach maximum compression, and the particles begin to 'pile up' into a bow wave. For air, this happens at Mach 1, and the air effectively becomes incompressible. Water is nearly incompressible from the get-go ( also, liquids and solids have transverse 'sound' waves as well as longitudinal ). That's why you see a bow wave on a boat doing 10 mph. That wave is the 'shock' of the particles bunching up because they can't move out of the way fast enough. Another ( huge ) problem would be cavitation. This is usually seen in pumps/propellers where the fluid can't flow fast enough into the area behind the pump/propeller blades, creating a low pressure area ( or even vacuum ) which tends to destroy equipment. For a plane the shock is the separation where supersonic air is drastically decelerated to subsonic ( inside the shock cone ), and it carries a lot of momentum/energy which is dissipated in the 'sonic boom'. If the 'sub' was at a shallow depth, with the surface close by, the spray pattern of the water shock into the air would be extremely interesting. to say the least. So the shock wave of travelling through water would be no different than through an incompressible fluid such as supersonic air, except for the cavitation problem, which I didn't consider on Sunday ( and which may make this idea a non-starter ).

A 'wormhole' is a shortcut through space-time, and, if used as a 'time machine', cannot get you back to a time before the wormhole was created. That being said, if the shortcut reduced a distance of 100 LY in regular space-time to one light month, it would still take you one month to traverse the wormhole. The length of the wormhole would be dependent on the topology of space-time as modified by the wormhole, and how it is 'constructed'. edit Purely theoretical, or for sci-fi, of course. I don't think wormholes are actually possible.

Two Broadcom distributors show up n a google search ... https://www.mouser.com/manufacturer/broadcom/ http://www.ameya360.com/mfrdetail/broadcom?utm_campaign=English&utm_medium=Google&utm_source=adwords&utm_content=guanjianzi&utm_term=Broadcom Otherwise you might try searching through eBay for used parts. The Pi 4 uses the BCM2711 4 core SoC, but that needs 4W; you might be better off with the lower power single or double core versions in earlier Pi.

Raspberry Pi uses a Broadcom processor, an in-house implementation of the ARM architecture ( see Acorn Business Machines RISC Microprocessor, a 32 bit outgrowth of the 8 bit MOStech 6502 processor used in the Apple II and Commodore/Atari ). I have no idea where you could source such a chip n small quantities. Your best bet would be either using a Pi motherboard ( with additions ), or cannibalizing one for chips ( de-soldering SM chips is difficult ). Here is some info on Raspberry Pi hardware ... https://www.raspberrypi.org/documentation/hardware/raspberrypi/

I have to wonder, then, how did other elementary particles, like the Quark colors and Neutrino flavors, come about ? They are certainly not 'made up' of Electrons and Positrons; and the current Big Bang/Standard model explains their origin fairly well. ( except for a few inconsistencies which may have something to do with the fundamental nature of quantum particles, such as matter/antimatter asymmetry, dark matter, Neutrino oscillations and strong CP problem )

So did I ( but I wasn't foolish enough to attempt writing an OS ). Now who's waxing nostalgic ?

Actually, they are just as possible as frictionless surfaces .

No, it doesn't rotate like a planet. An electron's spin is an intrinsic form of angular momentum. For an electron, return to its 'starting point' takes 720o. x-posted with Joigus

One question only... Is the solar power for recharging the battery only, or do you want to run off it as well? -If you intend to run off solar, I assume you'll spend a lot of time outdoors. ; you're going to need a very bright screen. -You might wanna give yourself a little more than a month, as companies like Lenovo and Apple, with much higher development budgets than you, still haven't been able to accomplish this. -This pretty well limits you to very low power chips, based on the ARM architecture ( think Raspberry Pi and Arduino SoC ); you certainly can't use X86 architecture ( not even Atom ). -You would want the solar panel to have optimum orientation to the Sun; that would be screen/keyboard areas on a standard laptop form factor, so not particularly suitable. Even optimally, a 1/2 square foot ( 6 x12 inch, fairly large ) panel will produce a peak ( instantaneous ) of slightly better than 7 Watts. If solar is intended for recharging only, will you be using it only at night and re-charging during the day ? ( maybe this is the reason Lenovo or Apple aren't developing such an impractical product )

Yeah, that happens to us 'old folk'.