Particle Scaling

static final int NUM_PRATICLES = 500;
Particle [] particles = new Particle[NUM_PRATICLES];

void setup() {
  size(500, 500);
  frameRate(30);
  for(int i = 0; i < NUM_PRATICLES; i++){
    particles[i] = new Particle();
  }
}

void draw() {
  background(255);
  pushMatrix();
  for (int i = 0; i < particles.length; i++) {
    particles[i].moveMe();
    particles[i].joinParticles(particles);
    particles[i].drawMe();
  }
  translate(width/2, height/2);
  popMatrix();
}

class Particle {
  float x, y;
  float r;
  float xSpeed, ySpeed;
  float xAcceleration, yAcceleration;
  float alpha;
  
  Particle() {
    x = random(0, width);
    y = random(0, height);
    r = random(1, 10);
    xSpeed = random(-2, 2);
    ySpeed = random(-2, 2);
    alpha = random(25, 250);
    xAcceleration = 0.0;
    yAcceleration = 0.0;
  }
  
  void drawMe() {
    noStroke();
    fill(39,57,75);
    circle(x, y, r);
  }
  
  void moveMe() {
    if (x < 0 || width < x) {
      xSpeed *= -1;
    }
    if (y < 0 || height < y) {
      ySpeed *= -0.975;
    }
    
    x += xSpeed;
    y += ySpeed;
    
    xAcceleration = (width/2 - x) / width;
    yAcceleration = (height/2 - y) / height;
    
    xSpeed += xAcceleration;
    ySpeed += yAcceleration;
  }
  
  void joinParticles(Particle particles[]) {
    for (int i = 0; i < particles.length; i++) {
      float distance = dist(x, y, particles[i].x, particles[i].y);
      if (distance < 50) {
        stroke(39, 57, 75, (50 - distance) / 10);
        line(x, y, particles[i].x, particles[i].y);
      }
    }
  }
}