GravitationalLens/index.html at master · porfanid/GravitationalLens · GitHub

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<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Gravitational Lensing Explained</title>
  <link href="https://cdnjs.cloudflare.com/ajax/libs/bootstrap/5.3.0/css/bootstrap.min.css" rel="stylesheet">
  <style>
    body {
      background-color: #0a0d22;
      color: #e0e0ff;
      font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    }

    .container {
      max-width: 1000px;
    }

    .header {
      padding: 40px 0;
      text-align: center;
      background: linear-gradient(to right, #0f1942, #1a103d);
      border-radius: 0 0 50px 50px;
      margin-bottom: 30px;
      box-shadow: 0 5px 25px rgba(0, 0, 0, 0.5);
    }

    h1 {
      font-weight: 700;
      color: #ffffff;
      text-shadow: 0 0 10px rgba(100, 149, 237, 0.8);
    }

    .subtitle {
      color: #add8e6;
      font-style: italic;
    }

    .lens-container {
      position: relative;
      margin: 50px auto;
      height: 400px;
      border-radius: 20px;
      background-color: rgba(10, 15, 40, 0.7);
      box-shadow: 0 5px 25px rgba(0, 0, 0, 0.3);
      overflow: hidden;
    }

    #lensCanvas {
      position: absolute;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
    }

    .info-card {
      background: linear-gradient(135deg, rgba(25, 25, 65, 0.9), rgba(10, 10, 30, 0.9));
      border-radius: 15px;
      border: 1px solid rgba(100, 149, 237, 0.3);
      padding: 25px;
      margin-bottom: 30px;
      box-shadow: 0 5px 15px rgba(0, 0, 0, 0.3);
      transition: transform 0.3s, box-shadow 0.3s;
    }

    .info-card:hover {
      transform: translateY(-5px);
      box-shadow: 0 10px 25px rgba(100, 149, 237, 0.2);
    }

    .info-card h3 {
      color: #add8e6;
      margin-bottom: 15px;
      border-bottom: 1px solid rgba(100, 149, 237, 0.3);
      padding-bottom: 10px;
    }

    .star {
      position: absolute;
      background-color: #fff;
      border-radius: 50%;
    }

    .footer {
      text-align: center;
      padding: 20px;
      margin-top: 40px;
      color: #7a85a8;
      font-size: 0.9em;
    }

    .controls {
      background: rgba(20, 30, 70, 0.7);
      padding: 15px;
      border-radius: 10px;
      margin-bottom: 20px;
    }

    .slider-container {
      margin-bottom: 15px;
    }

    .form-label {
      color: #add8e6;
    }

    .form-range::-webkit-slider-thumb {
      background: #4169e1;
    }

    .btn-primary {
      background-color: #4169e1;
      border: none;
    }

    .btn-primary:hover {
      background-color: #2a4fd6;
    }

    .example-images {
      display: flex;
      flex-wrap: wrap;
      justify-content: space-around;
      margin-top: 30px;
    }

    .example-image {
      width: 48%;
      margin-bottom: 20px;
      border-radius: 10px;
      overflow: hidden;
      box-shadow: 0 5px 15px rgba(0, 0, 0, 0.5);
    }

    .example-image img {
      width: 100%;
      transition: transform 0.3s;
    }

    .example-image:hover img {
      transform: scale(1.03);
    }

    .example-image .caption {
      background: rgba(30, 40, 80, 0.9);
      padding: 10px;
      font-size: 0.9em;
    }

    @media (max-width: 768px) {
      .example-image {
        width: 100%;
      }
    }

    .stars-bg {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      z-index: -1;
      overflow: hidden;
    }
  </style>
</head>
<body>
<div class="stars-bg" id="starsBg"></div>

<div class="container">
  <div class="header">
    <h1>Gravitational Lensing</h1>
    <p class="subtitle">Bending Light in the Cosmic Ocean</p>
  </div>

  <div class="row">
    <div class="col-md-6">
      <div class="info-card">
        <h3>What is Gravitational Lensing?</h3>
        <p>Gravitational lensing is a phenomenon where light from a distant source is bent due to the gravitational field of a massive object lying between the source and the observer.</p>
        <p>Predicted by Einstein's Theory of General Relativity, this effect allows astronomers to observe objects that would otherwise be hidden or too faint to detect.</p>
      </div>
    </div>

    <div class="col-md-6">
      <div class="info-card">
        <h3>How Does It Work?</h3>
        <p>Massive objects like galaxies and galaxy clusters curve spacetime around them. Light follows this curved path rather than traveling in a straight line.</p>
        <p>The bending can create multiple images, arcs, rings, or magnified views of distant cosmic objects, acting as a natural telescope in space.</p>
      </div>
    </div>
  </div>

  <div class="lens-container">
    <canvas id="lensCanvas"></canvas>
  </div>

  <div class="controls">
    <div class="row">
      <div class="col-md-4">
        <div class="slider-container">
          <label for="massSlider" class="form-label">Lens Mass</label>
          <input type="range" class="form-range" id="massSlider" min="5" max="50" value="30">
        </div>
      </div>
      <div class="col-md-4">
        <div class="slider-container">
          <label for="sourcePositionSlider" class="form-label">Source Position</label>
          <input type="range" class="form-range" id="sourcePositionSlider" min="0" max="100" value="50">
        </div>
      </div>
      <div class="col-md-4">
        <div class="slider-container">
          <label for="viewerDistanceSlider" class="form-label">Viewer Distance</label>
          <input type="range" class="form-range" id="viewerDistanceSlider" min="50" max="150" value="100">
        </div>
      </div>
    </div>
    <div class="text-center">
      <button id="resetBtn" class="btn btn-primary">Reset Simulation</button>
      <button id="stopBtn" class="btn btn-secondary ms-2">Stop</button>
    </div>
  </div>

  <div class="row">
    <div class="col-md-6">
      <div class="info-card">
        <h3>Types of Gravitational Lensing</h3>
        <p><strong>Strong Lensing:</strong> Creates multiple images, arcs, or Einstein rings when the alignment is nearly perfect.</p>
        <p><strong>Weak Lensing:</strong> Causes subtle distortions in the shapes of background galaxies, helping map dark matter.</p>
        <p><strong>Microlensing:</strong> Temporary brightness increases when a star passes in front of another star, used to detect exoplanets.</p>
      </div>
    </div>

    <div class="col-md-6">
      <div class="info-card">
        <h3>Scientific Value</h3>
        <p>Gravitational lensing helps astronomers:</p>
        <ul>
          <li>Detect and map dark matter</li>
          <li>Study very distant galaxies magnified by the lens effect</li>
          <li>Measure the Hubble constant and cosmic expansion</li>
          <li>Test theories of gravity on cosmic scales</li>
          <li>Discover exoplanets through microlensing events</li>
        </ul>
      </div>
    </div>
  </div>

  <div class="example-images">
    <div class="example-image">
      <img src="img/Einstein_Ring.JPG" alt="Einstein Ring">
      <div class="caption">Einstein Ring: When a source, lens, and observer are perfectly aligned, creating a complete ring.</div>
    </div>
    <div class="example-image">
      <img src="img/Einstein_cross.jpg" alt="Einstein Cross">
      <div class="caption">Einstein Cross: A quasar appears as four images around a foreground galaxy.</div>
    </div>
    <div class="example-image">
      <img src="img/GravitationalArc.jpg" alt="Gravitational Arcs">
      <div class="caption">Gravitational Arcs: Distant galaxies stretched into arcs by a massive galaxy cluster.</div>
    </div>
    <div class="example-image">
      <img src="img/Microlensingexoplanet.gif" alt="Microlensing Event">
      <div class="caption">Microlensing Event: Temporary brightening of a background star as another star passes in front of it.</div>
    </div>
  </div>

  <div class="footer">
    <p>© 2025 Pavlos Orfanidis. Created for educational purposes.</p>
  </div>
</div>

<script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap/5.3.0/js/bootstrap.bundle.min.js"></script>
<script>
  document.addEventListener('DOMContentLoaded', () => {

    let stopBtn = document.getElementById('stopBtn');
    let isAnimating = true;

    stopBtn.addEventListener('click', () => {
      isAnimating = !isAnimating;
      stopBtn.textContent = isAnimating ? 'Stop' : 'Resume';
      stopBtn.classList.toggle('btn-secondary', isAnimating);
      stopBtn.classList.toggle('btn-success', !isAnimating);
    });

    // Create starry background
    const starsBg = document.getElementById('starsBg');
    for (let i = 0; i < 200; i++) {
      createStar(starsBg);
    }

    // Canvas setup
    const canvas = document.getElementById('lensCanvas');
    const ctx = canvas.getContext('2d');

    // Set canvas dimensions
    function setCanvasSize() {
      canvas.width = canvas.offsetWidth;
      canvas.height = canvas.offsetHeight;
    }

    setCanvasSize();
    window.addEventListener('resize', setCanvasSize);

    // Simulation parameters
    let massSlider = document.getElementById('massSlider');
    let sourcePositionSlider = document.getElementById('sourcePositionSlider');
    let viewerDistanceSlider = document.getElementById('viewerDistanceSlider');
    let resetBtn = document.getElementById('resetBtn');

    // Simulation variables
    let mass = parseInt(massSlider.value);
    let sourcePosition = parseInt(sourcePositionSlider.value);
    let viewerDistance = parseInt(viewerDistanceSlider.value);

    // Light rays
    const rays = [];
    const numRays = 100;

    // Initialize rays
    function initRays() {
      rays.length = 0;
      const sourceX = canvas.width * (sourcePosition / 100);
      const sourceY = canvas.height * 0.2;

      for (let i = 0; i < numRays; i++) {
        const angle = (i / numRays) * Math.PI;
        rays.push({
          x: sourceX,
          y: sourceY,
          dx: Math.cos(angle) * 2,
          dy: Math.sin(angle) * 2,
          points: [{x: sourceX, y: sourceY}],
          color: `hsl(${(i / numRays) * 260}, 100%, 70%)`
        });
      }
    }

    // Gravitational lens
    const lens = {
      x: canvas.width / 2,
      y: canvas.height / 2,
      radius: 20
    };

    // Update lens position
    function updateLens() {
      lens.x = canvas.width / 2;
      lens.y = canvas.height / 2;
      lens.radius = mass / 2;
    }

    // Update ray positions
    function updateRays() {
      const sourceX = canvas.width * (sourcePosition / 100);
      const viewerY = canvas.height * (viewerDistance / 100);

      rays.forEach(ray => {
        // Reset ray to source
        ray.x = sourceX;
        ray.y = canvas.height * 0.2;
        ray.points = [{x: ray.x, y: ray.y}];

        // Trace ray until it reaches viewer or leaves canvas
        for (let steps = 0; steps < 1000; steps++) {
          // Calculate gravitational effect
          const dx = lens.x - ray.x;
          const dy = lens.y - ray.y;
          const distance = Math.sqrt(dx * dx + dy * dy);

          if (distance > 5) {  // Avoid division by zero and extreme deflection
            const force = mass / (distance * distance);
            ray.dx += dx / distance * force;
            ray.dy += dy / distance * force;
          }

          // Normalize direction vector
          const speed = Math.sqrt(ray.dx * ray.dx + ray.dy * ray.dy);
          ray.dx = ray.dx / speed * 2;
          ray.dy = ray.dy / speed * 2;

          // Move ray
          ray.x += ray.dx;
          ray.y += ray.dy;

          // Record position
          ray.points.push({x: ray.x, y: ray.y});

          // Check if ray reached viewer level or left canvas
          if (ray.y >= viewerY || ray.x < 0 || ray.x > canvas.width || ray.y < 0) {
            break;
          }
        }
      });
    }

    // Draw simulation
    function draw() {
      ctx.clearRect(0, 0, canvas.width, canvas.height);

      // Draw background
      const gradient = ctx.createLinearGradient(0, 0, 0, canvas.height);
      gradient.addColorStop(0, 'rgba(10, 10, 40, 0)');
      gradient.addColorStop(1, 'rgba(5, 5, 20, 0)');
      ctx.fillStyle = gradient;
      ctx.fillRect(0, 0, canvas.width, canvas.height);

      // Draw source
      const sourceX = canvas.width * (sourcePosition / 100);
      ctx.beginPath();
      ctx.arc(sourceX, canvas.height * 0.2, 8, 0, Math.PI * 2);
      ctx.fillStyle = 'rgba(255, 200, 100, 0.8)';
      ctx.fill();
      ctx.strokeStyle = 'rgba(255, 200, 100, 0.3)';
      ctx.lineWidth = 2;
      ctx.stroke();

      // Draw glow around source
      const sourceGlow = ctx.createRadialGradient(
        sourceX, canvas.height * 0.2, 0,
        sourceX, canvas.height * 0.2, 30
      );
      sourceGlow.addColorStop(0, 'rgba(255, 200, 100, 0.5)');
      sourceGlow.addColorStop(1, 'rgba(255, 200, 100, 0)');
      ctx.fillStyle = sourceGlow;
      ctx.fillRect(sourceX - 30, canvas.height * 0.2 - 30, 60, 60);

      // Draw lens
      ctx.beginPath();
      ctx.arc(lens.x, lens.y, lens.radius, 0, Math.PI * 2);
      ctx.fillStyle = 'rgba(100, 149, 237, 0.2)';
      ctx.fill();

      // Draw lens glow
      const lensGlow = ctx.createRadialGradient(
        lens.x, lens.y, lens.radius * 0.8,
        lens.x, lens.y, lens.radius * 3
      );
      lensGlow.addColorStop(0, 'rgba(100, 149, 237, 0.2)');
      lensGlow.addColorStop(1, 'rgba(100, 149, 237, 0)');
      ctx.fillStyle = lensGlow;
      ctx.beginPath();
      ctx.arc(lens.x, lens.y, lens.radius * 3, 0, Math.PI * 2);
      ctx.fill();

      // Draw viewer level
      const viewerY = canvas.height * (viewerDistance / 100);
      ctx.beginPath();
      ctx.moveTo(0, viewerY);
      ctx.lineTo(canvas.width, viewerY);
      ctx.strokeStyle = 'rgba(255, 255, 255, 0.2)';
      ctx.lineWidth = 1;
      ctx.setLineDash([5, 5]);
      ctx.stroke();
      ctx.setLineDash([]);

      // Draw rays
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        if (ray.points.length > 1) {
          ctx.beginPath();
          ctx.moveTo(ray.points[0].x, ray.points[0].y);

          for (let i = 1; i < ray.points.length; i++) {
            ctx.lineTo(ray.points[i].x, ray.points[i].y);
          }

          ctx.strokeStyle = ray.color;
          ctx.lineWidth = 1;
          ctx.globalAlpha = 0.3;
          ctx.stroke();
          ctx.globalAlpha = 1;
        }
      });

      // Draw image points where rays intersect viewer level
      const imagePts = rays.filter(ray => {
        const pts = ray.points;
        return pts.length > 1 && pts[pts.length-1].y >= viewerY;
      }).map(ray => {
        const pts = ray.points;
        const p1 = pts[pts.length-2];
        const p2 = pts[pts.length-1];

        // Calculate intersection with viewer line
        if (p1.y < viewerY && p2.y >= viewerY) {
          const t = (viewerY - p1.y) / (p2.y - p1.y);
          const x = p1.x + t * (p2.x - p1.x);
          return {x, color: ray.color};
        }
        return null;
      }).filter(pt => pt !== null);

      // Group nearby image points
      const groupedPoints = [];
      const groupThreshold = 10;

      imagePts.forEach(pt => {
        let added = false;
        for (const group of groupedPoints) {
          if (Math.abs(group.x - pt.x) < groupThreshold) {
            group.count++;
            group.x = (group.x * (group.count - 1) + pt.x) / group.count;
            added = true;
            break;
          }
        }
        if (!added) {
          groupedPoints.push({x: pt.x, count: 1, color: pt.color});
        }
      });

      // Draw the image points
      groupedPoints.forEach(pt => {
        const size = Math.min(8, Math.max(3, Math.sqrt(pt.count)));

        ctx.beginPath();
        ctx.arc(pt.x, viewerY, size, 0, Math.PI * 2);
        ctx.fillStyle = 'rgba(255, 200, 100, 0.8)';
        ctx.fill();

        // Draw glow
        const imgGlow = ctx.createRadialGradient(
          pt.x, viewerY, 0,
          pt.x, viewerY, size * 3
        );
        imgGlow.addColorStop(0, 'rgba(255, 200, 100, 0.5)');
        imgGlow.addColorStop(1, 'rgba(255, 200, 100, 0)');
        ctx.fillStyle = imgGlow;
        ctx.beginPath();
        ctx.arc(pt.x, viewerY, size * 3, 0, Math.PI * 2);
        ctx.fill();
      });

      // Add labels
      ctx.font = '14px Arial';
      ctx.fillStyle = 'rgba(255, 255, 255, 0.8)';
      ctx.fillText('Light Source', sourceX + 15, canvas.height * 0.2);
      ctx.fillText('Massive Object (Lens)', lens.x + lens.radius + 10, lens.y);
      ctx.fillText('Observer', 10, viewerY - 10);

      // Draw multiple images text if appropriate
      if (groupedPoints.length > 1) {
        ctx.font = '16px Arial';
        ctx.fillStyle = 'rgba(100, 255, 100, 0.8)';
        ctx.fillText(`${groupedPoints.length} images observed!`, canvas.width - 200, viewerY - 10);
      }
    }

    // Animation loop
    function animate() {
      if (isAnimating) {
        updateLens();
        updateRays();
        draw();
      }
      requestAnimationFrame(animate);
    }

    // Initialize
    function init() {
      mass = parseInt(massSlider.value);
      sourcePosition = parseInt(sourcePositionSlider.value);
      viewerDistance = parseInt(viewerDistanceSlider.value);

      updateLens();
      initRays();
    }

    // Event listeners
    massSlider.addEventListener('input', () => {
      mass = parseInt(massSlider.value);
    });

    sourcePositionSlider.addEventListener('input', () => {
      sourcePosition = parseInt(sourcePositionSlider.value);
      initRays();
    });

    viewerDistanceSlider.addEventListener('input', () => {
      viewerDistance = parseInt(viewerDistanceSlider.value);
    });

    resetBtn.addEventListener('click', init);

    // Create a star element
    function createStar(container) {
      const star = document.createElement('div');
      star.classList.add('star');

      // Random position
      const x = Math.random() * 100;
      const y = Math.random() * 100;

      // Random size (mostly small, occasionally larger)
      const size = Math.random() < 0.9 ? Math.random() * 2 : Math.random() * 4;

      // Random opacity for twinkling effect
      const opacity = 0.1 + Math.random() * 0.9;

      star.style.left = `${x}vw`;
      star.style.top = `${y}vh`;
      star.style.width = `${size}px`;
      star.style.height = `${size}px`;
      star.style.opacity = opacity;

      // Add twinkling animation
      star.style.animation = `twinkle ${2 + Math.random() * 4}s infinite`;

      container.appendChild(star);
    }

    // Start animation
    init();
    animate();
  });
</script>
<script src='https://storage.ko-fi.com/cdn/scripts/overlay-widget.js'></script>
<script>
  kofiWidgetOverlay.draw('porfanid', {
    'type': 'floating-chat',
    'floating-chat.donateButton.text': 'Support me',
    'floating-chat.donateButton.background-color': '#00b9fe',
    'floating-chat.donateButton.text-color': '#fff'
  });
</script>
</body>
</html>