Why Is Space Travel More Complex Than It Seems?

[Z0dCHiY8]

Most sources of pop culture & even engineering ones have failed to provide the key problems of space traveling. For example, dv ain't that hard as aerodynamics of Space. For 1st glance, it looks ridiculous == Space is Vacuum. Mostly, yes.. but Space has a lot of dust & gaseous clouds. Just one gram of material at 100 km/s equals to 5,000,000 Joules, it's roughly worthy to 1 kg of TNT & actually, far more lethal (detonation speed for tnt is only several km). Second trouble gets to be magnetic fields == at the least, eddy currents shall make a lot of noise onto spaceship sensors; more worse issue will be full blackout for unknown time; at worst scenario, sensors get fried entirely.

 

[trurle]

You should look at Breakthrough Starshot related research.
In brief, piercing interstellar medium at sub-light speed may be theoretically survivable for light-built spacecraft , although surface sputtering and radiation damage due ISM collisions are significant. Magnetic fields, on other hand, are insignificant - EMF is created by field gradients, not by field itself.

 

[Z0dCHiY8]

EMF is created by field gradients, not by field itself.

that's related to velocity of spaceship == greater speed, greater fluctuations of magnetic field.

piercing interstellar medium at sub-light speed may be theoretically survivable for light-built spacecraft

actually, the're a lot of problems to sail within Solar System even at 100 km/s.. sub-light speeds are purely suicidal. For instance, growing of relativistic mass can easily lead to explosion of fission or fusion reactor (under critical mass at normal speed become critical at sub-light). Electrical circuitry will run inadequately too. however, it's very unlikely to reach 1000 km/s w/o explosion by whatever reason.

 

[trurle]

For instance, growing of relativistic mass can easily lead to explosion of fission or fusion reactor (under critical mass at normal speed become critical at sub-light). Electrical circuitry will run inadequately too. however, it's very unlikely to reach 1000 km/s w/o explosion by whatever reason.

Effects like you describe are direct violation of principle of relativity.

 

[Z0dCHiY8]

what exact principle & how does it get violated?

 

[trurle]

what exact principle & how does it get violated?

https://en.wikipedia.org/wiki/Principle_of_relativity

 

[Z0dCHiY8]

exact example, please.

 

[phinds]

... growing of relativistic mass can easily lead to explosion of fission or fusion reactor

Since "relativistic mass" doesn't mean what you seem to think it means, that statement is nonsense.

 

[PeroK]

exact example, please.

All inertial references frames are equivalent. Or, to put it another way, a spaceship traveling at 100km/s relative to Earth is fundamentally equivalent to a spaceship at rest relative to the Earth. Neither ship is absolutely at rest, nor can you attribute any absolute velocity to either ship. It is not the case that the Earth represents some sort of special, absolutely at rest frame of reference.

In particular, relativistic mass represents the measure of the (kinetic) energy of one object in a reference frame in which it is moving. It does not represent any physical change in the object, as explained above.

For example, in the reference frame of the spaceship, the Earth is moving at 100km/s, but clearly the Earth undergoes no inherent physical change just because it is observed by something in relative motion to it.

 

[FactChecker]

The relativistic "mass" is only a crude explanation of how an outside, stationary, observer can understand what he is seeing in his time and space measurements. Considering it a real change of mass is widely discouraged and causes great confusion. The inertially moving person experiences all of his physics as though he is not moving at all. There will be no explosion of a reactor just because it is moving.

 

[PeterDonis]

growing of relativistic mass can easily lead to explosion of fission or fusion reactor (under critical mass at normal speed become critical at sub-light).

This is wrong. Criticality of a reactor does not depend on relativistic mass. It depends on mass in the reactor's rest frame, which does not change.

 

[Z0dCHiY8]

all our theoretical assumptions onto relativistic speeds could go further & further. Frame of reference is very contradictive term for all of that theory. For instance, how could we say about light speed, if we don't determine the Absolute Frame of Reference? Second moment, if speed of light is maximum for this Universe, how could we assume the same physics for all possible speeds of this Universe? It has no sense, if speed affects not just kinetic energy of body, but its time/geometry/mass. But my point stays for more humble ranges of velocity, for instance, we have curious statistics..

The majority of visible meteors are caused by particles ranging in size from about that of a small pebble down to a grain of sand, and generally weigh less than 1-2 grams.
------------------
The Leonid meteors represent the fastest known shower meteors, barreling in at 72 km/sec
https://www.amsmeteors.org/meteor-showers/meteor-faq/

even lightweight pieces of rock doesn't show astonishing speeds.

 

[phinds]

Frame of reference is very contradictive term for all of that theory.

No, it is not. Your understanding may be contradictory (not "contradictive") but that's your problem not a problem with physics.

For instance, how could we say about light speed, if we don't determine the Absolute Frame of Reference?

That's not a problem because there is no such thing as an absolute frame of reference

even lightweight pieces of rock doesn't show astonishing speeds.

That is incorrect. Relative to a particle in the CERN accelerator a small pebble laying on the ground next to your foot has an ASTONISHINGLY high speed (very close to the speed of light). For that matter, so do you.

 

[Z0dCHiY8]

That's not a problem because there is no such thing as an absolute frame of reference

And what is a point of maximum possible speed?

 

[phinds]

And what is a point of maximum possible speed?

The speed of light is a special case. It is the maximum possible actual speed and it is the same in all reference frames. You really need to study the basics some more.

 

[Z0dCHiY8]

The speed of light is a special case. It is the fastest possible actual speed and it is the same in all reference frames

well, then we cannot claim the same physics for all FoFs.

 

[Z0dCHiY8]

actually, i'd like to know why meteors get such humble limit of their velocity. :)

 

[PeterDonis]

This thread is degenerating into personal speculation by the OP and is now closed.