SPACETIME EXPLORER

Gravity’s Effects on Space & Time

Explore warped space, changing clocks, and worlds in motion.

INTERACTIVE EXPLAINER · NOT TO SCALE
COMPACT STAR · ILLUSTRATIVE SPATIAL GRID
Drag to orbit · Pinch / scroll to zoom · Arrow keys rotateColored points → matching clocks above
0% removes the glow; the solid surface and gravity remain.
Try this: start an ellipse, then change mass mid-flight. Position and velocity stay continuous; the new pull changes the future path. Orbit presets restart the planets at the current mass. Restart orbits leaves clocks and camera alone; Reset restores everything. Trails show the actual recent path. Solar System mode includes Mercury through Neptune in order, with compressed spacing and exaggerated sizes—not real distances, masses, or period ratios. These are eight independent test planets, not a full Solar System model.
All clocks advance together through the same simulation. One real second = 1 simulated minute. Changing mass or preset resets the clocks for a fair comparison. Grid exaggeration, lattice brightness, and star brightness change only the picture.
What this shows—and where the analogy stops

The clocks are quantitative; the lattice is illustrative. Each colored point represents a clock held stationary at a fixed distance from a nonrotating spherical mass. Its rate relative to a far-away reference is √(1 − rₛ/r), where rₛ = 2GM/c². All points and the stellar surface remain outside rₛ. The white reference is at infinity; it has no finite location in the scene.

The grid bends inward to make the mass’s influence visible. It is not a literal fabric, a flow of space, a coordinate-invariant picture, or a numerical solution of Einstein’s equations. Actual spacetime includes time as well as three spatial dimensions. The Sun-like preset uses rₛ/R = 0.00000424 at mass strength 1; the compact preset uses 0.5. Displayed distances are in stellar-radius units (R).

The planets are Newtonian test particles accelerated by the central star, integrated with fixed-step velocity Verlet. Orbital time uses independent illustrative units, not the clock display’s seconds. This is not a relativistic orbit prediction, especially in the compact-star setting. Planets do not gravitationally interact with one another; a collision with the surface stops that planet and travel beyond 60 R removes it from the simulation. Their small moving grid distortions are qualitative. Their gravity, orbital time dilation, light bending, frame dragging, and the mechanics of holding clocks in place are not included in the clock calculation. In reality these effects also matter. The compact preset is an educational idealization, not our solar system.

A slower clock is not broken: each observer experiences their own seconds normally. The difference appears when clocks are compared. Real gravitational clock differences are measured and matter in systems such as GPS.