---
name: "lightspeed"
section: "1"
platform: "linux"
package: "lightspeed"
version: "1.2a.debian.1-3"
release: "Debian 11 (Bullseye)"
platforms: ["linux"]
url: "https://new.carta.tech/lightspeed"
---

# lightspeed(1)

Shows how objects moving at speeds near the speed of light look like.

## NAME

lightspeed - Shows how objects moving at speeds near the speed of light look like.

## SYNOPSIS

**lightspeed** *\[***-hsa***\] \[***object***\]*

## DESCRIPTION

Light Speed! is a simulator which can illustrate the effects of special relativity on the appearance of objects travelling at ultra-high speeds. Depending on the particular speed, and one's point of view, relativistic effects can cause the object to appear shorter, longer, brighter, darker, deformed and/or off-color.

## CONTROLS

To adjust the velocity, use the slider along the right edge of the main window. You can also type in a value, using the entry at the top right (press \<Enter\> once it is in). To change the units shown, press the button to the right of the entry, and it will cycle through a small list.

The object travels in the positive-x direction, which can be visually checked by activating Objects -\> Coordinate axes.

Most interactive control is performed with the mouse. By holding down a particular button, and dragging the pointer around, various camera motions can be obtained:

```
   Left button:  Revolve camera around view target
   Left button + Shift key:  Revolve view target around camera
   Middle button:  Translate camera left, right, up or down
   Right button:  Dolly in or out
```

The first and last motions are generally the most useful. Should the camera become difficult to control at any point, it may be re-initialized by selecting Camera -\> Reset View.

## OPTIONS

- **-h**, **--help**

  Print this help screen

- **-s**, **--simple**

  Use simplified interface

- **-a**, **--advanced**

  Use advanced interface (default)

- *object*

  3D file to load on startup (.3DS or .LWO)