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If the moon were only 1 pixel: A tediously accurate solar system model (2014)

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Re: If the moon were only 1 pixel: A tediously accurate solar system model (2014)

#131

Post by eslaught »

raxxorraxor wrote: post #74
munksbeer wrote: post #9

Earlier quoted context omitted.

> Light is incredibly slow, and everything seems out of reach. Yes, agreed. I find it a little depressing. An unimaginably huge universe, tantalisingly there, but completely out of reach.

Not out of reach if you get very close to light speed. Time would advance very slowly for you, so counterintuitively it is possible to travel 5000ly in your life time. Although for everyone else at least 5000 years will pass, so better say goodbye to family and friend. Hm, not sure if that is really less depressing... Also light isn't slow. A photon instantly travels to the end of time and yet it still takes a few mi…

One thing I've always wondered is what fraction of c is actually realistically achievable with current technologies? (Maybe with scenarios for manned/unmanned spacecraft.)

Like are we at 0.1% or 0.01% or more orders of magnitude off?

Re: If the moon were only 1 pixel: A tediously accurate solar system model (2014)

#132

Post by silasdb »

This is a great website—it reminds me of To Scale: The Solar System [1], a mini-documentary where people attempt to build a true-to-scale model of the Solar System. It makes me feel like a tiny speck of dust, floating in the vastness of nowhere...

[1] https://www.youtube.com/watch?v=zR3Igc3Rhfg

Re: If the moon were only 1 pixel: A tediously accurate solar system model (2014)

#133

Post by jandrese »

kqr wrote: post #93
amelius wrote: post #91

Earlier quoted context omitted.

What are the chances of hitting a small meteorite or part of it, traveling now at relativistic speeds wrt you?

Extremely low. Space is very empty.

It's one of those cases where you have very small numbers multiplied by very large ones. The actual risk is hard to intuit because there are so many orders of magnitude involved in both directions.

In any case it's probably a moot concern as long as we are living under the twin tyrannies of Newtons Third Law and the Rocket Equation. Building a rocket that can accelerate constantly and noticeably for weeks, months, or even years on end in order to accelerate up to a velocity where Relativity starts to matter requires an absurdly large rocket. Like converting the mass of Jupiter into rocket fuel to make it to the next habitable solar system in a couple of centuries level of craziness.

Re: If the moon were only 1 pixel: A tediously accurate solar system model (2014)

#134

Post by IAmBroom »

brazzy wrote: post #105
jadbox wrote: post #99

Unrelated, but the Elon dream of getting a human colony on Mars seems beyond imagination. Ignoring safety of such a long travel, the radiation issue of Mar's surface, and the massive infrastructure to have a self-sustainable biosphere (also somehow protected from radiation) to recycle enough oxygen, we still have to deal with the immense number of failures that could happen with no way to send help. Like, building a…

It's very clearly not "beyond imagination". It doesn't require any fundamentally new technology. It may well be beyond our ability to practically apply those technologies at the required scales and reliability levels, but that's hardly unimaginable.

Preventing cancerous damage from radiation is absolutely beyond our tech.

Unless you consider launching a lead-lined spaceship "within our tech."

The marsonauts won't die before reaching Mars, but their lifespans will be significantly shortened.

Re: If the moon were only 1 pixel: A tediously accurate solar system model (2014)

#135

Post by jandrese »

TheOtherHobbes wrote: post #98
kqr wrote: post #94

Earlier quoted context omitted.

https://en.m.wikipedia.org/wiki/Generation_ship

To make a generation ship work you have to build a self-contained ecology that is stable and self-repairing, inside mechanical and software systems that are fault tolerant and either extremely redundant or self-repairing, run by a political and social system that is also fault-tolerant and self-repairing. We know how to do exactly zero of those things.

More to the point the ship needs to be absolutely self sufficient, it can't even use solar power and has no access to outside mass whatsoever. But if you have a ship like this you could build an orbital habitat using the same technology, and it would be much much easier to build since it doesn't have to accelerate, can use solar power, and has access to the rest of the resources of a solar system.

If you have all of this why would you go to the enormous extra effort to move the habitat to a different solar system? Even if your civilization is so old that the star is a dim brown dwarf that's still plenty of energy for day to day life.

Re: If the moon were only 1 pixel: A tediously accurate solar system model (2014)

#136

Post by doph »

seanw444 wrote: post #107
Sharlin wrote: post #87

Earlier quoted context omitted.

You’d feel nothing out of the ordinary whatsoever. The starscape outside the ship would look strange though, shrinking into a small, blueshifted patch of sky straight ahead, while stars behind you would redshift out of the visible range. Everything moving at very low speeds relative to you would indeed appear to happen really fast.

If the light behind you redshifts out of the visible spectrum, would the light in front of you blueshift into dangerous territory? X-rays, gamma rays, etc?

Yes, and this provides a nice intuition about the relation of wavelength to energy. But x and γ wavelengths are several oom shorter than visible light, so you'd have to be traveling at very close to c to experience that amount of Doppler shift.

Re: If the moon were only 1 pixel: A tediously accurate solar system model (2014)

#137

Post by Kuyawa »

j_m_b wrote: post #92

One of my favorite visualizations of the scale of the solar system is from Stephen Hawking's Genius. https://mass.pbslearningmedia.org/resource/hawking_genius_ep... It's a hands-on, practical example of how far things are away that we can easily visualize. I highly recommend the rest of the series as well. It's one of the best science shows ever produced. It shows the practical path of scientific discovery. You can w…

I've always used this aprox dimensions:

  Sun diam   1,400,000 km
  Eth diam      13,000 km
  Sun dist 150,000,000 km
  Mon diam       3,500 km
  Mon dist     300,000 km
Lets divide it all by 1M. So if the sun is 1.4m in diameter, it would be located 150m from earth which would be 13mm in diameter and the moon would be 3.5mm located 0.3m from earth

Simply put, imagine a yellow beach ball the size of a washing machine located a block and a half away from your house, a blue marble being the earth on one side of your keyboard and a peanut being the moon on the other side

Re: If the moon were only 1 pixel: A tediously accurate solar system model (2014)

#138

Post by jandrese »

Reubachi wrote: post #68
sestep wrote: post #36

Earlier quoted context omitted.

Naive question: is accelerating at 1G continuously within the range of what we consider possible?

Amazingly, yes, in a few ways (the mechanics are possible). But no in as many ways. (Fuel, sustainability, tracking) The greater barrier is that the nature of the expansion of the universe prevents any real interstellar travel that has a "destination" in mind. Of course we might have some "FTL" or "near light speed" travel in futre, but if the universe is expanding infintely from every point in space at light speed,…

If your travel involves the Rocket Equation the answer is no. If you are limited by the speed of light and the lifetime of human civilization then the expansion of the universe is not an issue. Traveling between nearby solar systems is very close to impossible, traveling between galaxies is outright impossible.

Re: If the moon were only 1 pixel: A tediously accurate solar system model (2014)

#139

Post by gwbas1c »

TheOtherHobbes wrote: post #98
kqr wrote: post #94

Earlier quoted context omitted.

https://en.m.wikipedia.org/wiki/Generation_ship

To make a generation ship work you have to build a self-contained ecology that is stable and self-repairing, inside mechanical and software systems that are fault tolerant and either extremely redundant or self-repairing, run by a political and social system that is also fault-tolerant and self-repairing. We know how to do exactly zero of those things.

> run by a political and social system that is also fault-tolerant and self-repairing

That's the point of the AI; it would generally replace that.

Re: If the moon were only 1 pixel: A tediously accurate solar system model (2014)

#140

Post by jandrese »

jadbox wrote: post #99

Unrelated, but the Elon dream of getting a human colony on Mars seems beyond imagination. Ignoring safety of such a long travel, the radiation issue of Mar's surface, and the massive infrastructure to have a self-sustainable biosphere (also somehow protected from radiation) to recycle enough oxygen, we still have to deal with the immense number of failures that could happen with no way to send help. Like, building a…

> Like, building a fully self-sustainable underwater city or moon base would be far more in reach. It feels that SpaceX should start with prototyping these safer alternatively before overreaching to something 100x more challenging and dangerous.

I've been beating this drum for years. Elon is 100% focused on building the rocket that can get to Mars and neglecting absolutely everything else about the project. Where is the self contained biosphere pilot program on Earth that tests the Mars habitat? To be anywhere close to Elon's timetable it needs to be running today, and honestly it should have been running years ago. Given the extreme reliability requirements it needs long term testing to build any confidence at all in the numerous technologies involved. The closest model we have is the ISS, and it's mostly shown that we aren't ready for a Mars habitat. The ISS requires way too much maintenance and ground support.

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