Orbital Resonance in Universe Sandbox 2

Universe Sandbox 2 is as much about breaking the rules as it is following them.  This is why you’re given the ability to add Saturn-like rings to any body, whether it’s Earth, Mars, or even the Sun. And it’s also why we allow you to put in all kinds of interesting but unrealistic shapes for the ‘rings,’ like spirals and cubes.  But, of course, we are also committed to incorporating and simulating as much science as we can. So we’ve included resonance gaps.

Adding realistic rings to the Sun produces several resonance gaps.

Adding realistic rings to the Sun produces several resonance gaps.

The basic idea here is that a larger body, like a moon (in the case of a ring around a planet), or a planet (in the case of rings around a star) creates gaps, or resonances, as seen in the picture above.

Here’s how it works (and for simplicity’s sake, just imagine circular orbits): According to Kepler’s third law, the distance an object is away from the planet determines how long it takes to orbit. That means that for an object at a given distance (and orbital period),  there must be a distance where the orbit takes only half the time, and another distance that takes three times as long. Whenever the two orbits take integer ratios of each other, we say the orbits are in resonance. For example, if the moon takes 28 days to orbit, there is a distance that only takes 14 days to orbit. This would be the 2:1 resonance (two orbits for every one orbit of the moon). If there is a disk present, and there is material at that distance, then every other time the material in the disk orbits, the moon has gone the whole way around, and the disk material comes as close to the moon as it can get — basically they are in the same part of their respective orbits. Each time that happens, the moon’s gravity pulls on the material just a little bit. For certain ratios of orbit periods, this little extra pull will clear the material out of that particular orbit. It’s really an amazing process that takes a fair bit of time to occur. But we see it in Saturn’s rings and we see it in the asteroid belt, where resonances with Jupiter have cleared out gaps (the Kirkwood gaps). And here is a great little animation showing resonance in Jupiter’s moons.

We calculate a handful of unstable resonances (3:1, 5:2, 7:3, 2:1, 7:6, and 1:1). So when you’re playing around with Universe Sandbox 2, and you include resonance gaps, you’ll see these rifts in the rings.  If you select the Sun and try to add rings, we find the planets that orbit the Sun, compute the resonances, and put gaps there, as pictured above. It’s pretty slick, if I do say so myself.

This feature includes the gaps when a ring is placed around an object. But Universe Sandbox is a gravity simulator, and this is a gravitational process. In principle, the gaps would develop on their own if you let the simulation run long enough. In practice, though, the simulation would need very, very high precision and to run for a very, very long time, and until we are running Universe Sandbox on a supercomputer, ring gaps won’t develop spontaneously.

You can also place your own rings by specifying the inner and outer boundaries of a single ring. So you could build up a single ring system with gaps anywhere you’d like them to be. We hope you have fun playing around with this feature when we make Universe Sandbox 2 available for purchase. I sure had fun coding it up.

In other ring-related news, it was announced last week, to everyone’s surprise, that an asteroid in our Solar System called Chariklo has 2 rings. Here it is in Universe Sandbox 2:

Chariklo, Pluto, Mars, Venus, & Earth

Chariklo, Pluto, Mars, Venus, & Earth

 

Why do small stars not age past 12.6 billion years in Universe Sandbox 2?

Universe Sandbox 2, currently in development, is a powerful gravity simulator that invites you to learn about our amazing universe and fragile planet via an expanding realm of realistic, interconnected astronomy and climate physics systems. Read more about this upcoming version here: The New Universe Sandbox.  Or find out how to purchase the currently available version at universesandbox.com/buy/.

Q:  In Universe Sandbox 2, small stars, such as red dwarfs, stop aging when they reach 12.6 billion years old.  Why is this?

A:  Stellar evolution is incredibly complicated. We understand the basics of it quite well, and for a lot of stars, our models do a really good job of matching up to measurements of real stars. It is, however, very hard to do this right, for several reasons:

1. We don’t have perfect data.

We can’t directly measure the mass or radius of a real star. And even something like the temperature of a star isn’t always easy to measure. This means that a lot of the data are rough estimations.
One really big issue is what astronomers call ‘metallicity’. Basically, what is the relative fraction of elements in a star? How much iron is there, relative to hydrogen, etc?

2. We can’t actually observe the evolution of a single star.

We can watch it, but so far, we’ve only been watching for maybe a few decades or so, depending on when you consider our technology to have been good enough to do any of this.  In star years, that’s not even a blink of the eye.  So we have to make assumptions about the way a star will age by looking at other, older stars. It’s like looking at a whole bunch of people and guessing how you will age by seeing what older people look like right now. You can make an estimation, but it won’t be exact, because how you age depends a bit on what you eat, what happens to you, your genes, etc., and these factors are inevitably different than those of the older folks. Similarly, we can guess what the sun will do, but it has slightly different properties of the stars we think it will look like.

3.  We can’t see inside a star.

And this is where most of the action happens. So this is all based on physics calculations. We’re good at that, but not perfect.

Hertzsprung–Russell diagram in Universe Sandbox. The HR Diagram (star's temperature versus luminosity) was introduced in the early 20th century and helped pave the way for a better understanding of stellar evolution.

Hertzsprung–Russell diagram in Universe Sandbox. The HR Diagram (star’s temperature versus luminosity) was introduced in the early 20th century and helped pave the way for a better understanding of stellar evolution.

Okay, now on to how this directly relates to Universe Sandbox 2:

Since stellar evolution is so hard, we let the full-time, professional astronomers compute the models. We’ve adopted a whole suite of these stellar evolution models, or “isochrones.”  These isochrones tell us the temperature, radius, and luminosity for a range of stellar masses and ages, and we turn that data into what you see in Universe Sandbox.

Unfortunately, although these isochrones are quite good and pretty accurate, they don’t give us predictions for very low-mass stars (less than 10% of the Sun’s mass) or very high-mass stars. And they don’t give us predictions for longer timeframes, such as 12.6 billion years (recall the age of the universe is a bit less than 14 billion years).

So this is what we’re stuck with for the time being. In the future, we’re planning on incorporating some other isochrones that are focused on lower-mass stars (which call for different physics, since the stellar atmospheres are very different; at low temperatures, molecules and even clouds can form in the stellar atmosphere, requiring different models), higher mass stars, different metallicities, and longer timeframes.

This is a work in progress, but we’ll be making it better and better as we go.

Follow the links below to read more about stellar evolution and some of the terms used in this post.

http://en.wikipedia.org/wiki/Stellar_evolution
http://en.wikipedia.org/wiki/Stellar_isochrone
http://en.wikipedia.org/wiki/Metallicity
http://stev.oapd.inaf.it/cgi-bin/cmd

Universe Sandbox 75% off at Huge Seal

The Huge Seal Steam coupon giveaway continues for 5 more days!

Head on over to hugeseal.com to get Universe Sandbox for 75% off.

Use two more coupons and you’ll get another game completely free.

From their site: Huge Seal is a Steam Discount Coupon giveaway where you get to choose 5 Steam Discount Coupons from a list of over 30 indie games by logging on to hugeseal.com with your Steam account. And when you purchase 3 games with the coupons, you get one random Steam key for free!

The campaign ends on November 24th, so be sure to get going while the going is good!

And while you’re busy clicking links, be sure to Like us on Facebook and follow us on Twitter @UniverseSandbox.

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Collision System Architect & Physics Programmer

We are no longer seeking applicants for this position.

We’re looking for a enthusiastic physics programmer interested in developing a system for handling planetary collisions (and collisions at other scales of objects) for the upcoming sequel to Universe Sandbox. This is a contract position, but has the potential to become more permanent.

You’ll be working with the creator of Universe Sandbox, our astronomer, the core game architect, the developer of our gravity integrator and smooth particle hydrodynamics tech, and aiding our graphics programmer. We are creating a robust, real time model for collisions of objects at all scales – asteroids, planets, moons, and stars (and smaller human sized objects) that works at wide range of time steps (including super slow motion). The collision system will need to work with variable numbers of spawned bodies and particles with smooth transitions between all states.

We want to create a system that will handle the Moon colliding with the Earth, the Earth colliding with Jupiter, Jupiter colliding with another gas giant, and something that works when a user decides to spawn a black hole inside of a moon.

You will oversee the integration of existing collision physics analytical and numerical solutions into one system that smoothly transitions between the handling of various cases, making sure that edge cases are accounted for.

Our continuing goal is to make the easiest and most captivating way to learn about the universe through real-time interaction, creation, and destruction… while keeping the simulation representative and true to our best understanding of reality.

Join a talented team and let’s make something amazing that’s never been created before.

In short: collisions must be amazing.

Requirements

  • Physics programming experience
  • Love watching slow motion videos of collisions and explosions
  • Interest in helping change the way the world perceives our universe and fragile planet

Ideally

  • Strong C# and Unity experience
  • Experience with rigid body physics systems like: PhysX, Jitter, or Bullet
  • Ability to meet in person at least once a week in the Capitol Hill neighborhood of Seattle, WA

Company Overview

Giant Army is the company behind Universe Sandbox, a space simulator that’s sold hundreds of thousands of copies on Steam. We’re based in Seattle, Washington, USA, but the team has members in Montana, Germany, and Denmark.

Product Overview

Universe Sandbox is our core product that lets the user explore and learn about our amazing universe while creating and destroying on a scale they’ve never before imagined. It’s more than a game; it’s a way of experiencing and learning about reality in a way that’s never been done before. The new version will be available for Windows, Mac, and Linux.

Interested?

We are no longer seeking applicants for this position.

If you’re interested please email us at:
jobs at universesandbox.com

In the email please include a:

  • Relevant email subject
  • Answer to these two questions:
    - What is the most appealing part of this opportunity?
    - What aspect of physics simulations do you find most interesting?
  • Link to where you originally heard about this job posting
  • Link to or copy of your resume

 

Current State of Collisions and Development

We’ve been developing the sequel to Universe Sandbox in C# and Unity for 2 years. We have a great Open CL based gravity integrator and an analytical system in place for simple collisions that works fairly well. We have ideas for how to move forward with this, but there’s too much else for everyone to do for this critical feature to get the attention it needs. We’re open to new ideas and rebuilding the existing system to get the best end result.

Hiring a Personal Assistant

We are no longer seeking applicants for this position.

We’re a successful software company that created the astronomy game / educational simulation Universe Sandbox. We’re looking to hire a business/personal assistant to help with the many things involved in running a business outside of the development of the software itself. This position has the potential to grow in hours and responsibility over the next few months and years.

We’re looking for someone with the following qualifications to work both remotely and onsite in the Capitol Hill neighborhood of Seattle, WA several hours a week to start. We want someone who enjoys this kind of work, not someone looking to get into the actual development of video games.

Requirements

  • Strong written communication skills (and verbal too)
  • Highly organized
  • Self-driven fast learner
  • Trustworthy & reliable
  • Technology & software savvy
  • Reasonable understanding of social networks and marketing
  • Ability to meet in person at least once a week in the Capitol Hill neighborhood of Seattle, WA (and perhaps more frequently at first for training).
  • Interest in astronomy and/or video games and/or education
  • Knowledge of the internets and tubes
  • Interest in helping change the way the world perceives our universe and fragile planet

Responsibilities

  • Responding to email, forum posts, and basic support
  • Handling media inquiries
  • Summarizing user feedback
  • Helping maintain the FAQ
  • Proofreading and document creation/editing (press releases, blog posts, web site content)
  • Posting to social media
  • Scheduling meetings, organizing travel
  • Updating tasks, organizing documents
  • Managing email
  • Helping with random events as they occur

This is a both an onsite & remote, part time, hourly contract position.

Company Overview

Giant Army is the company behind Universe Sandbox, a space simulator that’s sold hundreds of thousands of copies on Steam. We’re based in Seattle, Washington, USA, but the team has members in Germany and Denmark.

Product Overview

Universe Sandbox is our core product that lets the user explore and learn about our amazing universe while creating and destroying on a scale they’ve never before imagined. It’s more than a game, it’s a way of experiencing and learning about reality in a way that’s never been done before. The new version will be available for Windows, Mac, and Linux.

Interested?

We are no longer seeking applicants for this position.

If you’re interested please email us at:
jobs at universesandbox.com

In the email please include a:

  • Relevant email subject
  • Short answer to these two questions:
    - Why are you interested in working for Giant Army?
    - What is the most appealing part of this opportunity?
  • Link to where you heard about this job posting
  • Copy or link to your resume

Procedural Planets

Just a quick screenshot that shows off what Georg has been focusing on for the last couple weeks and a new feature he just got implemented earlier today: Lava!

Universe Sandbox - 20131003-023307

One of the many goals for the sequel to Universe Sandbox is that almost everything can be procedurally generated… galaxies, solar systems, and planets. This screenshot represents the current state of the procedural planet feature (and includes a few Earths for scale).

And a nod to the hard work of the rest of the team: Chris, Eric, Thomas, and Naomi. They’re all doing really great work.

Learn more about the sequel:
http://universesandbox.com/blog/2013/02/new-universe-sandbox/

 

We’re Hiring a Personal Assistant

We’re still looking… check out the new post:
http://universesandbox.com/blog/2013/10/hiring-a-personal-assistant/

 

Now Hiring UI & Logo Designer

We’ve been hard at work over the last year building a new Universe Sandbox from the ground up. And since we’re improving everything we want to extend that to the UI design and branding.

We’re seeking one (possibly two) talented graphic designer(s) for the following contract work:

 

User Interface Design

Design the way the buttons, panels, checkboxes, options, controls, typography, selection indicators, and icons work together aesthetically. We’d love your help in figuring out how the interface will work as well as how it will look. Universe Sandbox has a very complex interface and we want something that’s clean, modern, minimalist,  and unobtrusive.

Here’s are screenshots of the current version with the existing UI…
http://universesandbox.com/screenshots/

And a work-in-progress screenshot of the sequel:

Universe Sandbox - 20130425-151116

Again, the screenshot is very much a work in progress… Just imagine how awesome the above screenshot could look after we integrate your user interface design.

To be clear… we’re looking for a designer and not expecting you to do any of the integration, programming, or scripting (and our user interface system is inextricably tied to the source code for the project).

 

New Logo

Design a new logo for the rebranding of Universe Sandbox. We’re pretty happy with the current logo and typography, but want something even better for the new version of Universe Sandbox. Here’s the current logo:

uslogo-onwhite-300

We’re open to something that’s just a re-imagining or something completely new… either way we want a logo that’s clean, elegant, and awesome. It should work on both black and white backgrounds…  and the logo should work well both as a standalone icon and with the full typography.

 

Company Overview

Giant Army is the company behind Universe Sandbox, a space simulator that’s sold hundreds of thousands of copies on Steam. We’re based in Seattle, Washington, USA, but the team has members in Germany and Denmark.

 

Product Overview

Universe Sandbox is our core product that lets the user explore and learn about our amazing universe while creating and destroying on a scale they’ve never before imagined. It’s more than a game, it’s a way of experiencing and learning about reality in a way that’s never been done before. The new version will be available for Windows, Mac, and probably Linux.

 

Interested?

We’re a remote team so it doesn’t matter where you live.

And while this is a contract position for a specific task… we’d love to establish a relationship with a talented artist or two as there are many future projects we have in mind (like more logos, business cards, a new website, signage for conferences, perpetual UI enhancements, and other awesome stuff).

Please email us at:
jobs at universesandbox.com

In the email please include a:

  • Relevant email subject
  • Link to relevant samples of your work (kinda the most important part)
  • Short answer to this question: Why are you interested in working on this project?
  • Link to where you first heard about this job posting.

If you have questions you’d like to ask before applying… feel free to ask at the email address above, on the official forums, the Steam forums, or on Facebook.

We want to take our time and find someone who’s excited about helping contribute to great software that will reach a huge number of people (and who won’t mind being paid for their efforts).

The New Universe Sandbox

Universe Sandbox 2 is a full rewrite of the original Universe Sandbox for Windows, Mac, and Linux. In development since late 2011, we are working hard to make the new version more amazing than the original in every way. We can’t wait to release it to everyone, but won’t release it until it’s ready.

The new Universe Sandbox is a way of learning about our amazing universe and fragile planet via a powerful gravity simulator and an expanding realm of realistic and interconnected astronomy and climate physics systems.

 

Universe Sandbox - 20130429-185438

 

Here is a collection of links to forum posts about the new version currently in development.

Screenshots

October 2013 – Procedural Planets

April 2012

October 2012

November 2012

 

Videos

Live demonstration from August 2012

Early Collision Tests


Info on Release & Beta

Upgrades & Updates: The Future of Universe Sandbox

Beta Release Plan

 

Universe Sandbox - 20130714-010257

Universe Sandbox is Now Free to Schools

Update on Universe Sandbox for Schools, 2014

We are offering Universe Sandbox free to all those who wish to use it in their classrooms.  If you are interested in using Universe Sandbox for educational purposes, please complete this Google Form: Universe Sandbox for Schools.

We will contact you shortly with further information about receiving a free copy for your school.

(This offer was previously supported by Steam for Schools, a program run by Valve.  Unfortunately, they are no longer running this service. While the website is still up and running, they are no longer accepting applications, so do not contact either Valve or Steam about receiving Universe Sandbox for your school.  Below is the original blog post about this service.)

Universe Sandbox is now part of Steam for Schools, a service from Valve.

Steam for Schools is  free to any school anywhere in the world and also includes Valve’s Portal 2.

Schools can sign up for this free program and learn more from their website:
http://www.teachwithportals.com/

2013-06-05 22_40_21-Teach with Portals