Psychedelic Backgrounds

Create a new image, 300x300px, then create a new layer ('Layer > New > Layer'). Fill the new layer with any color using the paint bucket.

Double click the new layer in the Layers window and add a Gradient Overlay. Click the gradient to modify it (circled in red below):

Change the settings shown to create a noise gradient. If you do not like the colors of your gradient, keep clicking the Randomize button until you're happy.

Here is what I came up with:

Right click your new layer and select 'Merge Down.' This will combine the new layer and the background layer, and apply the gradient so it is not a layer style anymore.

Go to 'Filter > Blur > Radial Blur' and enter the following settings:

Here is the final image. Try different gradients and settings for the blur for different results.

Now let's turn it up a notch. Save your image if desired, then create a new layer and fill it with any color with the paint bucket. This time, add a Pattern Overlay Layer Style. Use the Nebula pattern.

Your new layer should look like this. Just like before, right click the new layer in the Layers window and select Merge Down. You should now have one layer.

Go to 'Filter > Stylize > Glowing Edges' and enter the following settings:

Here is the result:

Now go to 'Filter > Liquify' and when the Liquify window comes up, keep clicking & dragging around until you get a nice outcome. I like to drag from the middle towards the outside. If you make a mistake, you can use 'Ctrl+Z' to undo. Here are the settings I used:

And here is the final result: