This page will help you solve some of the problems people commonly have running our programs. If you can't solve your problem here, please notify us by email at the following email address: email@example.com.
Common Troubleshooting Issues
Where do I start if the simulations do not run on my computer?
First, update to the latest version of Java: http://java.com/en/.
Run the latest version of the sim directly from phet.colorado.edu by clicking the 'Run Now' button on the sim page. e.g.: Energy Forms and Changes.
If you are using a Mac please see here for detailed instructions.
Why can I run some of the simulations but not all?
The original sims are programmed in Java or Flash. Flash is installed in most modern desktop web browsers while Java is a free application that can be downloaded from Oracle. To run the Java-based simulations you must have Java version 1.5 or higher installed on your computer. To download the latest version of Java, please visit: https://www.java.com.
If you are running the sims on a tablet or Chromebook see here info on compatible sims.
Why don't Flash simulations run on my computer?
QuickTime™ and Flash™ compatibility
It has come to our attention that some of our users are unable to use our Flash-based simulations due to a compatibility issue between Apple Computer's QuickTime™ and the Flash™ player. Some users have reported that uninstalling QuickTime resolves the issue.
We are aware that this is not an acceptable solution and are working to resolve this issue. If you are experiencing this problem, please contact us at at firstname.lastname@example.org and regularly check back here for more information.
Why do PhET simulations run slower on my laptop than on a desktop?
On some laptop computers, simulations may appear to run much slower than anticipated and/or exhibit unexpected graphics problems. This may be due to power management settings that affect how the computer's graphics system runs and can be corrected by either a) changing the computer's power management configuration, or b) using the laptop computer while plugged in to an AC power source.
Many laptop computers are configured to reduce the amount of battery power used by the graphics/video system while the computer is running on battery power. If you must use the laptop while it is not plugged in, we suggest changing your computer's power management settings to "maximize performance" while unplugged. This should ensure that the graphics system runs at its peak speed. The location of this setting varies from one manufacturer to the next and we suggest contacting your computer vendor if you have difficulty locating it. Please contact us at email@example.com if you continue to encounter problems.
Why does my computer crash when I run one of the simulations that has sound?
Simulations that use sound can be unstable when run on computers using old device driver software. If you are encountering crashes or other undesirable behavior with any of our simulations that use sound, we advise updating your sound drivers, as this may solve the problem. For assistance with updating your sound drivers, contact your computer vendor or audio hardware manufacturer. Contact us at firstname.lastname@example.org if you continue to encounter difficulty.
I have downloaded and installed the PhET Offline Website Installer, and I get a warning on every page. Why?
The PhET Offline Website Installer creates a local copy of the current version of the PhET website on your computer. When you access this locally installed copy, your computer will use your default browser, which for many people is Internet Explorer. If the security settings are set to their default values, you may get an error that says "To help protect your security, Internet Explorer has restricted this webpage from running scripts or ActiveX controls that could access your computer. Click here for options..." (or something similar). This is a security feature of Internet Explorer version 6 and later, and is meant to warn users about running active content locally. The PhET simulations present no danger to your computer, and running them locally is no different than running them from the web site.
If you wish to disable this warning, you can do so by adjusting your browser's security settings. For IE versions 6 and 7, the way to do this is to go into Tools->Internet Options->Advanced, find the "Security" heading, and check "Allow active content to run in files on My Computer". Note that you will need to restart Internet Explorer to get this change to take effect. You should only do this if feel confident that there is no other off-line content that you may run on your computer that could be malicious.
Alternatively, you could use a different browser (such as Firefox) that does not have this issue.
When I run simulations from the PhET Offline Website Installer, I am seeing a dialog that says "The application's digital signature has been verified. Do you want to run the application?" (or something similar). What does this mean?
The PhET simulations that are distributed with the installer include a "digital certificate" that verifies that these simulations were actually created by PhET. This is a security measure that helps to prevent an unscrupulous individual from creating applications that claim to be produced by PhET but are not. If the certificate acceptance dialog says that the publisher is "PhET, University of Colorado", and the dialog also says that the signature was validated by a trusted source, you can have a high degree of confidence that the application was produced by the PhET team.
On most systems, it is possible to permanently accept the PhET certificate and thereby prevent this dialog from appearing each time a simulation is run locally. Most Windows and Max OSX systems have a check box on the certificate acceptance dialog that says "Always trust content from this publisher". Checking this box will configure your system in such a way that the dialog will no longer appear when starting up PhET simulations.
Why do some foreign language characters show up as empty boxes?
Some characters from non-English languages will show up as empty squares when the proper fonts are not installed. Below are instructions to install additional language support for various operating systems:
- Windows 2000 / XP: http://support.microsoft.com/kb/177561
- Windows Vista: http://windows.microsoft.com/en-US/windows-vista/How-do-I-get-additional-language-files
- Windows 7: http://support.microsoft.com/kb/972813
- OS X: http://support.apple.com/kb/DL1123?viewlocale=en_US